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Sample records for rg zn cd

  1. Photoluminescence study of the substitution of Cd by Zn during the growth by atomic layer epitaxy of alternate CdSe and ZnSe monolayers

    SciTech Connect (OSTI)

    Hernndez-Caldern, I.; Salcedo-Reyes, J. C.

    2014-05-15

    We present a study of the substitution of Cd atoms by Zn atoms during the growth of alternate ZnSe and CdSe compound monolayers (ML) by atomic layer epitaxy (ALE) as a function of substrate temperature. Samples contained two quantum wells (QWs), each one made of alternate CdSe and ZnSe monolayers with total thickness of 12 ML but different growth parameters. The QWs were studied by low temperature photoluminescence (PL) spectroscopy. We show that the Cd content of underlying CdSe layers is affected by the exposure of the quantum well film to the Zn flux during the growth of ZnSe monolayers. The amount of Cd of the quantum well film decreases with higher exposures to the Zn flux. A brief discussion about the difficulties to grow the Zn{sub 0.5}Cd{sub 0.5}Se ordered alloy (CuAu-I type) by ALE is presented.

  2. CdS and CdS/CdSe sensitized ZnO nanorod array solar cells prepared by a solution ions exchange process

    SciTech Connect (OSTI)

    Chen, Ling; Gong, Haibo; Zheng, Xiaopeng; Zhu, Min; Zhang, Jun; Yang, Shikuan; Cao, Bingqiang

    2013-10-15

    Graphical abstract: - Highlights: CdS and CdS/CdSe quantum dots are assembled on ZnO nanorods by ion exchange process. The CdS/CdSe sensitization of ZnO effectively extends the absorption spectrum. The performance of ZnO/CdS/CdSe cell is improved by extending absorption spectrum. - Abstract: In this paper, cadmium sulfide (CdS) and cadmium sulfide/cadmium selenide (CdS/CdSe) quantum dots (QDs) are assembled onto ZnO nanorod arrays by a solution ion exchange process for QD-sensitized solar cell application. The morphology, composition and absorption properties of different photoanodes were characterized with scanning electron microscope, transmission electron microscope, energy-dispersive X-ray spectrum and Raman spectrum in detail. It is shown that conformal and uniform CdS and CdS/CdSe shells can grow on ZnO nanorod cores. Quantum dot sensitized solar cells based on ZnO/CdS and ZnO/CdS/CdSe nanocable arrays were assembled with gold counter electrode and polysulfide electrolyte solution. The CdS/CdSe sensitization of ZnO can effectively extend the absorption spectrum up to 650 nm, which has a remarkable impact on the performance of a photovoltaic device by extending the absorption spectrum. Preliminary results show one fourth improvement in solar cell efficiency.

  3. Post-Growth Annealing of Bridgman-grown CdZnTe and CdMnTe Crystals for

    Office of Scientific and Technical Information (OSTI)

    Room-temperature Nuclear Radiation Detectors (Journal Article) | SciTech Connect Post-Growth Annealing of Bridgman-grown CdZnTe and CdMnTe Crystals for Room-temperature Nuclear Radiation Detectors Citation Details In-Document Search Title: Post-Growth Annealing of Bridgman-grown CdZnTe and CdMnTe Crystals for Room-temperature Nuclear Radiation Detectors Bridgman-grown cadmium zinc telluride (CdZnTe or CZT) and cadmium manganese telluride (CdMnTe or CMT) crystals often have Te inclusions that

  4. Wide emission-tunable CdTeSe/ZnSe/ZnS core-shell quantum dots...

    Office of Scientific and Technical Information (OSTI)

    Title: Wide emission-tunable CdTeSeZnSeZnS core-shell quantum dots and their conjugation with E. coli O-157 Highlights: * QDs with variety morphology were obtained via an ...

  5. Core-shell ITO/ZnO/CdS/CdTe nanowire solar cells

    SciTech Connect (OSTI)

    Williams, B. L.; Phillips, L.; Major, J. D.; Durose, K.; Taylor, A. A.; Mendis, B. G.; Bowen, L.

    2014-02-03

    Radial p-n junction nanowire (NW) solar cells with high densities of CdTe NWs coated with indium tin oxide (ITO)/ZnO/CdS triple shells were grown with excellent heterointerfaces. The optical reflectance of the devices was lower than for equivalent planar films by a factor of 100. The best efficiency for the NW solar cells was ??=?2.49%, with current transport being dominated by recombination, and the conversion efficiencies being limited by a back contact barrier (?{sub B}?=?0.52?eV) and low shunt resistances (R{sub SH}?

  6. Analysis of Surface Chemistry and Detector Performance of Chemically Process CdZnTe crystals

    SciTech Connect (OSTI)

    HOSSAIN A.; Yang, G.; Sutton, J.; Zergaw, T.; Babalola, O. S.; Bolotnikov, A. E.; Camarda. ZG. S.; Gul, R.; Roy, U. N., and James, R. B.

    2015-10-05

    The goal is to produce non-conductive smooth surfaces for fabricating low-noise and high-efficiency CdZnTe devices.

  7. Wide emission-tunable CdTeSe/ZnSe/ZnS core-shell quantum dots and their

    Office of Scientific and Technical Information (OSTI)

    conjugation with E. coli O-157 (Journal Article) | SciTech Connect Wide emission-tunable CdTeSe/ZnSe/ZnS core-shell quantum dots and their conjugation with E. coli O-157 Citation Details In-Document Search Title: Wide emission-tunable CdTeSe/ZnSe/ZnS core-shell quantum dots and their conjugation with E. coli O-157 Highlights: * QDs with variety morphology were obtained via an injection controlled process. * 3-D PL spectra of core-shell QDs show different excitation wavelength dependence. *

  8. Purification of CdZnTe by Electromigration

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kim, K.; Kim, Sangsu; Hong, Jinki; Lee, Jinseo; Hong, Taekwon; Bolotnikov, A. E.; Camarda, G. S.; James, R. B.

    2015-04-14

    Electro-migration of ionized/electrically active impurities in CdZnTe (CZT) was successfully demonstrated at elevated temperature with an electric field of 20 V/mm. Copper, which exists in positively charged states, electro-migrated at a speed of 15 lm/h in an electric field of 20 V/mm. A notable variation in impurity concentration along the growth direction with the segregation tendency of the impurities was observed in an electro-migrated CZT boule. Notably, both Ga and Fe, which exist in positively charged states, exhibited the opposite distribution to that of their segregation tendency in Cd(Zn)Te. Furthermore, a CZT detector fabricated from the middle portion of themore » electromigrated CZT boule showed an improved mobility-lifetime product of 0.91 10-2 cm2 /V, compared to that of 1.4 10-3 cm2 /V, observed in an as-grown (non-electro-migrated) CZT detector. The optimum radiation detector material would have minimum concentration of deep traps required for compensation.« less

  9. CdSe/ZnSe quantum dot structures grown by molecular beam epitaxy with a CdTe submonolayer stressor

    SciTech Connect (OSTI)

    Sedova, I. V. Lyublinskaya, O. G.; Sorokin, S. V.; Sitnikova, A. A.; Toropov, A. A.; Donatini, F.; Dang, Si Le; Ivanov, S. V.

    2007-11-15

    A procedure for formation of CdSe quantum dots (QDs) in a ZnSe matrix is suggested. The procedure is based on the introduction of a CdTe submonolayer stressor deposited on the matrix surface just before deposition of the material of the QDs. (For CdTe/ZnSe structure, the relative lattice mismatch is {delta}a/a {approx} 14%.) The stressor forms small strained islands at the ZnSe surface, thus producing local fields of high elastic stresses controlling the process of the self-assembling of the QDs. According to the data of transmission electron microscopy, this procedure allows a considerable increase in the surface density of QDs, with a certain decrease in their lateral dimensions (down to 4.5 {+-} 1.5 nm). In the photoluminescence spectra, a noticeable ({approx}150 meV) shift of the peak to longer wavelengths from the position of the reference CdSe/ZnSe QD structure is observed. The shift is due to some transformation of the morphology of the QDs and an increase in the Cd content in the QDs. Comprehensive studies of the nanostructures by recording and analyzing the excitation spectra of photoluminescence, the time-resolved photoluminescence spectra, and the cathodoluminescence spectra show that the emission spectra involve two types of optical transitions, namely, the type-I transitions in the CdSeTe/ZnSe QDs and the type-II transitions caused mainly by the low cadmium content (Zn,Cd)(Se,Te)/ZnSe layer formed between the QDs.

  10. CdSe self-assembled quantum dots with ZnCdMgSe barriers emitting throughout the visible spectrum

    SciTech Connect (OSTI)

    Perez-Paz, M. Noemi; Zhou Xuecong; Munoz, Martin; Lu Hong; Sohel, Mohammad; Tamargo, Maria C.; Jean-Mary, Fleumingue; Akins, Daniel L.

    2004-12-27

    Self-assembled quantum dots of CdSe with ZnCdMgSe barriers have been grown by molecular beam epitaxy on InP substrates. The optical and microstructural properties were investigated using photoluminescence (PL) and atomic force microscopy (AFM) measurements. Control and reproducibility of the quantum dot (QD) size leading to light emission throughout the entire visible spectrum range has been obtained by varying the CdSe deposition time. Longer CdSe deposition times result in a redshift of the PL peaks as a consequence of an increase of QD size. AFM studies demonstrate the presence of QDs in uncapped structures. A comparison of this QD system with CdSe/ZnSe shows that not only the strain but also the chemical properties of the system play an important role in QD formation.

  11. Luminescence of CdSe/ZnS quantum dots infiltrated into an opal matrix

    SciTech Connect (OSTI)

    Gruzintsev, A. N. Emelchenko, G. A.; Masalov, V. M.; Yakimov, E. E.; Barthou, C.; Maitre, A.

    2009-02-15

    The effect of the photonic band gap in the photonic crystal, the synthesized SiO{sub 2} opal with embedded CdSe/ZnS quantum dots, on its luminescence in the visible spectral region is studied. It is shown that the position of the photonic band gap in the luminescence and reflectance spectra for the infiltrated opal depends on the diameter of the constituent nanospheres and on the angle of recording the signal. The optimal conditions for embedding the CdSe/ZnS quantum dots from the solution into the opal matrix are determined. It is found that, for the opal-CdSe/ZnS nanocomposites, the emission intensity decreases and the luminescence decay time increases in the spatial directions, in which the spectral positions of the photonic band gap and the luminescence peak of the quantum dots coincide.

  12. Synthesis and optical study of green light emitting polymer coated CdSe/ZnSe core/shell nanocrystals

    SciTech Connect (OSTI)

    Tripathi, S.K.; Sharma, Mamta

    2013-05-15

    Highlights: ► Synthesis of Polymer coated core CdSe and CdSe/ZnSe core/shell NCs. ► From TEM image, the spherical nature of CdSe and CdSe/ZnSe is obtained. ► Exhibiting green band photoemission peak at 541 nm and 549 nm for CdSe core and CdSe/ZnSe core/shell NCs. ► The shell thickness has been calculated by using superposition of quantum confinement energy model. - Abstract: CdSe/ZnSe Core/Shell NCs dispersed in PVA are synthesized by chemical method at room temperature. This is characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV/Vis spectra and photoluminescence spectroscopy (PL). TEM image shows the spherical nature of CdSe/ZnSe core/shell NCs. The red shift of absorption and emission peak of CdSe/ZnSe core/shell NCs as compared to CdSe core confirmed the formation of core/shell. The superposition of quantum confinement energy model is used for calculation of thickness of ZnSe shell.

  13. Effects of Cu Diffusion from ZnTe:Cu/Ti Contacts on Carrier Lifetime of CdS/CdTe Thin Film Solar Cells: Preprint

    SciTech Connect (OSTI)

    Gessert, T. A.; Metzger, W. K.; Asher, S. E.; Young, M. R.; Johnston, S.; Dhere, R. G.; Duda, A.

    2008-05-01

    We study the performance of CdS/CdTe thin film PV devices processed with a ZnTe:Cu/Ti contact to investigate how carrier lifetime in the CdTe layer is affected by Cu diffusion from the contact.

  14. Effects of chemo-mechanical polishing on CdZnTe X-ray and gamma-ray

    Office of Scientific and Technical Information (OSTI)

    detectors (Journal Article) | SciTech Connect Effects of chemo-mechanical polishing on CdZnTe X-ray and gamma-ray detectors Citation Details In-Document Search This content will become publicly available on June 23, 2016 Title: Effects of chemo-mechanical polishing on CdZnTe X-ray and gamma-ray detectors Here, mechanically polishing cadmium zinc telluride (CdZnTe) wafers for x-ray and gamma-ray detectors often is inadequate in removing surface defects caused by cutting them from the ingots.

  15. Simulation, Modeling, and Crystal Growth of Cd0.9Zn0.1Te for Nuclear

    Office of Scientific and Technical Information (OSTI)

    Spectrometers (Journal Article) | SciTech Connect Simulation, Modeling, and Crystal Growth of Cd0.9Zn0.1Te for Nuclear Spectrometers Citation Details In-Document Search Title: Simulation, Modeling, and Crystal Growth of Cd0.9Zn0.1Te for Nuclear Spectrometers High-quality, large (10 cm long and 2.5 cm diameter), nuclear spectrometer grade Cd{sub 0.9}Zn{sub 0.1}Te (CZT) single crystals have been grown by a controlled vertical Bridgman technique using in-house zone refined precursor materials

  16. The effects of deep level traps on the electrical properties of semi-insulating CdZnTe

    SciTech Connect (OSTI)

    Zha, Gangqiang; Yang, Jian; Xu, Lingyan; Feng, Tao; Wang, Ning; Jie, Wanqi

    2014-01-28

    Deep level traps have considerable effects on the electrical properties and radiation detection performance of high resistivity CdZnTe. A deep-trap model for high resistivity CdZnTe was proposed in this paper. The high resistivity mechanism and the electrical properties were analyzed based on this model. High resistivity CdZnTe with high trap ionization energy E{sub t} can withstand high bias voltages. The leakage current is dependent on both the deep traps and the shallow impurities. The performance of a CdZnTe radiation detector will deteriorate at low temperatures, and the way in which sub-bandgap light excitation could improve the low temperature performance can be explained using the deep trap model.

  17. Removal of Zn or Cd and cyanide from cyanide electroplating wastes

    DOE Patents [OSTI]

    Moore, Fletcher L.

    1977-05-31

    A method is described for the efficient stripping of stable complexes of a selected quaternary amine and a cyanide of Zn or Cd. An alkali metal hydroxide solution such as NaOH or KOH will quantitatively strip a pregnant extract of the quaternary ammonium complex of its metal and cyanide content and regenerate a quaternary ammonium hydroxide salt which can be used for extracting further metal cyanide values.

  18. New acceptor centers of the background impurities in p-CdZnTe

    SciTech Connect (OSTI)

    Plyatsko, S. V. Rashkovetskyi, L. V.

    2013-07-15

    Low-temperature photoluminescence data are used to study the redistribution of the background impurities and host components of p-CdZnTe single crystals with a resistivity of 1-50 {Omega} cm upon their interaction with infrared laser radiation. The effect of widening of the band gap and the formation of new acceptor centers in response to laser-stimulated changes in the system of intrinsic defects are established. The activation energy of the new acceptor centers is determined.

  19. Spectral photoresponse of ZnSe/GaAs(001) heterostructures with CdSe ultra-thin quantum well insertions

    SciTech Connect (OSTI)

    Valverde-Chvez, D. A.; Sutara, F.; Hernndez-Caldern, I.

    2014-05-15

    We present a study of the spectral photoresponse (SPR) of ZnSe/GaAs(001) heterostructures for different ZnSe film thickness with and without CdSe ultra-thin quantum well (UTQW) insertions. We observe a significant increase of the SPR of heterostructures containing 3 monolayer thick CdSe UTQW insertions; these results encourage their use in photodetectors and solar cells.

  20. Intersubband absorption in CdSe/Zn{sub x}Cd{sub y}Mg{sub 1-x-y}Se self-assembled quantum dot multilayers

    SciTech Connect (OSTI)

    Shen, A.; Lu, H.; Charles, W.; Yokomizo, I.; Tamargo, M. C.; Franz, K. J.; Gmachl, C.; Zhang, S. K.; Zhou, X.; Alfano, R. R.; Liu, H. C.

    2007-02-12

    The authors report the observation of intersubband absorption in multilayers of CdSe/Zn{sub x}Cd{sub y}Mg{sub 1-x-y}Se self-assembled quantum dots. The samples were grown by molecular beam epitaxy on InP substrates. For samples with the CdSe dot layers doped with Cl and with the deposited CdSe equivalent layer thickness between 5.2 and 6.9 ML, peak absorption between 2.5 and 3.5 {mu}m was observed. These materials are promising for intersubband devices operating in the mid- and near-infrared ranges.

  1. Impact of annealing on the chemical structure and morphology of the thin-film CdTe/ZnO interface

    SciTech Connect (OSTI)

    Horsley, K. Hanks, D. A.; Weir, M. G.; Beal, R. J.; Wilks, R. G.; Blum, M.; Hming, M.; Hofmann, T.; Weinhardt, L.; and others

    2014-07-14

    To enable an understanding and optimization of the optoelectronic behavior of CdTe-ZnO nanocomposites, the morphological and chemical properties of annealed CdTe/ZnO interface structures were studied. For that purpose, CdTe layers of varying thickness (424?nm) were sputter-deposited on 100?nm-thick ZnO films on surface-oxidized Si(100) substrates. The morphological and chemical effects of annealing at 525?C were investigated using X-ray Photoelectron Spectroscopy (XPS), X-ray-excited Auger electron spectroscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy, and atomic force microscopy. We find a decrease of the Cd and Te surface concentration after annealing, parallel to an increase in Zn and O signals. While the as-deposited film surfaces show small grains (100?nm diameter) of CdTe on the ZnO surface, annealing induces a significant growth of these grains and separation into islands (with diameters as large as 1??m). The compositional change at the surface is more pronounced for Cd than for Te, as evidenced using component peak fitting of the Cd and Te 3d XPS peaks. The modified Auger parameters of Cd and Te are also calculated to further elucidate the local chemical environment before and after annealing. Together, these results suggest the formation of tellurium and cadmium oxide species at the CdTe/ZnO interface upon annealing, which can create a barrier for charge carrier transport, and might allow for a deliberate modification of interface properties with suitably chosen thermal treatment parameters.

  2. Reduction of surface leakage current by surface passivation of CdZn Te and other materials using hyperthermal oxygen atoms

    DOE Patents [OSTI]

    Hoffbauer, Mark A.; Prettyman, Thomas H.

    2001-01-01

    Reduction of surface leakage current by surface passivation of Cd.sub.1-x Zn.sub.x Te and other materials using hyperthermal oxygen atoms. Surface effects are important in the performance of CdZnTe room-temperature radiation detectors used as spectrometers since the dark current is often dominated by surface leakage. A process using high-kinetic-energy, neutral oxygen atoms (.about.3 eV) to treat the surface of CdZnTe detectors at or near ambient temperatures is described. Improvements in detector performance include significantly reduced leakage current which results in lower detector noise and greater energy resolution for radiation measurements of gamma- and X-rays, thereby increasing the accuracy and sensitivity of measurements of radionuclides having complex gamma-ray spectra, including special nuclear materials.

  3. Effects of hydrogen on the optical properties of ZnCdO/ZnO quantum wells grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Buyanova, I. A.; Wang, X. J.; Chen, W. M.; Pozina, G.; Lim, W.; Norton, D. P.; Pearton, S. J.; Osinsky, A.; Dong, J. W.; Hertog, B.

    2008-06-30

    Temperature-dependent cw- and time-resolved photoluminescence (PL), as well as optically detected magnetic resonance (ODMR) measurements are employed to evaluate effects of deuterium (2H) doping on optical properties of ZnCdO/ZnO quantum well structures grown by molecular beam epitaxy. It is shown that incorporation of {sup 2}H from a remote plasma causes a substantial improvement in radiative efficiency of the investigated structures. Based on transient PL measurements, the observed improvements are attributed to efficient passivation by hydrogen of competing nonradiative recombination centers via defects. This conclusion is confirmed from the ODMR studies.

  4. Photoluminescence Enhancement in CdSe/ZnSDNA linkedAu Nanoparticle Heterodimers Probed by Single Molecule Spectroscopy

    SciTech Connect (OSTI)

    Cotlet, M.; Maye, M.M.; Gang, O.

    2010-07-26

    Photoluminescence enhancement of up to 20 fold is demonstrated at the single molecule level for heterodimers composed of a core/shell CdSe/ZnS semiconductive quantum dot and a gold nanoparticle of 60 nm size separated by a 32 nm-long dsDNA linker when employing optical excitation at wavelengths near the surface plasmon resonance of the gold nanoparticle.

  5. Photo-instability of CdSe/ZnS quantum dots in poly(methylmethacrylate) film

    SciTech Connect (OSTI)

    Zhang, Hongyi; Liu, Yu; Ye, Xiaoling; Chen, Yonghai

    2013-12-28

    The photo-instability of CdSe/ZnS quantum dots (QDs) has been studied under varied conditions. We discussed the main features of the evolution of photoluminescence (PL) intensity and energy at different laser powers, which showed critical dependences on the environment. The PL red shift in a vacuum showed strong temperature dependence, from which we concluded that the thermal activation energy for trapping states of the charge carriers was about 14.7 meV. Furthermore, the PL spectra showed asymmetric evolution during the laser irradiation, for which two possible explanations were discussed. Those results provided a comprehensive picture for the photo-instability of the colloidal QDs under different conditions.

  6. Use of separate ZnTe interface layers to form ohmic contacts to p-CdTe films

    DOE Patents [OSTI]

    Gessert, T.A.

    1999-06-01

    A method of is disclosed improving electrical contact to a thin film of a p-type tellurium-containing II-VI semiconductor comprising: depositing a first undoped layer of ZnTe on a thin film of p-type tellurium containing II-VI semiconductor with material properties selected to limit the formation of potential barriers at the interface between the p-CdTe and the undoped layer, to a thickness sufficient to control diffusion of the metallic-doped ZnTe into the p-type tellurium-containing II-VI semiconductor, but thin enough to minimize affects of series resistance; depositing a second heavy doped p-type ZnTe layer to the first layer using an appropriate dopant; and depositing an appropriate metal onto the outer-most surface of the doped ZnTe layer for connecting an external electrical conductor to an ohmic contact. 11 figs.

  7. Use of separate ZnTe interface layers to form OHMIC contacts to p-CdTe films

    DOE Patents [OSTI]

    Gessert, Timothy A.

    1999-01-01

    A method of improving electrical contact to a thin film of a p-type tellurium-containing II-VI semiconductor comprising: depositing a first undoped layer of ZnTe on a thin film of p-type tellurium containing II-VI semiconductor with material properties selected to limit the formation of potential barriers at the interface between the p-CdTe and the undoped layer, to a thickness sufficient to control diffusion of the metallic-doped ZnTe into the p-type tellurim-containing II-VI semiconductor, but thin enough to minimize affects of series resistance; depositing a second heavy doped p-type ZnTe layer to the first layer using an appropriate dopant; and depositing an appropriate metal onto the outer-most surface of the doped ZnTe layer for connecting an external electrical conductor to an ohmic contact.

  8. CD

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    CD .... -- en .. CD :II -- = .= * = = = * en CD .= .... .... * E CD i .. CD .... * .. 1:11 CD .... = - = III HL W -99-0008 Revision 10 June 1999 with October 1999 Update High Level Waste Division High Level Waste System Plan Revision 10 (U) Contributors: Prepared by: A. S. Choi P. Paul F. E. Wise Approved by: t....,..~'O:"::""f-..:-........::::::::.....t..--=+--7"'f-------- W.G. Poulson Vice President and General Manager High Level Waste Division Wesfnghouse Sav nnah River

  9. Investigation of the Effect of I-ZnO Window Layer on the Device Performance of the Cd-Free CIGS Based Solar Cells: Preprint

    SciTech Connect (OSTI)

    Hasoon, F. S.; Al-Thani, H. A.; Li, X.; Kanevce, A.; Perkins, C.; Asher, S.

    2008-05-01

    This paper focuses on preparing Cd-free, CIGS-based solar cells with intrinsic high resistivity ZnO (I-ZnO) films deposited by metal-organic chemical vapor deposition (MOCVD) technique at different deposition substrate temperature and I-ZnO film thickness, and the effect of the prior treatment of CIGS films by ammonium hydroxide (NH4OH) diluted solution on the device performance.

  10. Post-Growth Annealing of Bridgman-grown CdZnTe and CdMnTe Crystals...

    Office of Scientific and Technical Information (OSTI)

    temperature gradient, we observed the migration of Te inclusions from a low-temperature ... These results show that the migration, diffusion, and reaction of Te with Cd in the matrix ...

  11. Atomic arrangement at ZnTe/CdSe interfaces determined by high resolution scanning transmission electron microscopy and atom probe tomography

    SciTech Connect (OSTI)

    Bonef, Bastien; Rouvire, Jean-Luc; Jouneau, Pierre-Henri; Bellet-Amalric, Edith; Grard, Lionel; Mariette, Henri; Andr, Rgis; Bougerol, Catherine; Grenier, Adeline

    2015-02-02

    High resolution scanning transmission electron microscopy and atom probe tomography experiments reveal the presence of an intermediate layer at the interface between two binary compounds with no common atom, namely, ZnTe and CdSe for samples grown by Molecular Beam Epitaxy under standard conditions. This thin transition layer, of the order of 1 to 3 atomic planes, contains typically one monolayer of ZnSe. Even if it occurs at each interface, the direct interface, i.e., ZnTe on CdSe, is sharper than the reverse one, where the ZnSe layer is likely surrounded by alloyed layers. On the other hand, a CdTe-like interface was never observed. This interface knowledge is crucial to properly design superlattices for optoelectronic applications and to master band-gap engineering.

  12. Post-Growth Annealing of Bridgman-grown CdZnTe and CdMnTe Crystals for Room-temperature Nuclear Radiation Detectors

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Egarievwe, Stephen U.; Yang, Ge; Egarievwe, Alexander; Okwechime, Ifechukwude O.; Gray, Justin; Hales, Zaveon M.; Hossain, Anwar; Camarda, Guiseppe S.; Bolotnikov, Aleksey E.; James, Ralph B.

    2015-02-11

    Bridgman-grown cadmium zinc telluride (CdZnTe or CZT) and cadmium manganese telluride (CdMnTe or CMT) crystals often have Te inclusions that limit their performances as X-ray- and gamma-ray-detectors. We present here the results of post-growth thermal annealing aimed at reducing and eliminating Te inclusions in them. In a 2D analysis, we observed that the sizes of the Te inclusions declined to 92% during a 60-h annealing of CZT at 510 °C under Cd vapor. Further, tellurium inclusions were eliminated completely in CMT samples annealed at 570 °C in Cd vapor for 26 h, whilst their electrical resistivity fell by an ordermore » of 102. During the temperature-gradient annealing of CMT at 730 °C and an 18 °C/cm temperature gradient for 18 h in a vacuum of 10-5 mbar, we observed the diffusion of Te from the sample, causing a reduction in size of the Te inclusions. For CZT samples annealed at 700 °C in a 10 °C/cm temperature gradient, we observed the migration of Te inclusions from a low-temperature region to a high one at 0.022 μm/s. During the temperature-gradient annealing of CZT in a vacuum of 10-5 mbar at 570 °C and 30 °C/cm for 18 h, some Te inclusions moved toward the high-temperature side of the wafer, while other inclusions of the same size, i.e., 10 µm in diameter, remained in the same position. These results show that the migration, diffusion, and reaction of Te with Cd in the matrix of CZT- and CMT-wafers are complex phenomena that depend on certain conditions.« less

  13. Electrically driven single photon emission from a CdSe/ZnSSe single quantum dot at 200?K

    SciTech Connect (OSTI)

    Quitsch, Wolf; Kmmell, Tilmar; Bacher, Gerd; Gust, Arne; Kruse, Carsten; Hommel, Detlef

    2014-09-01

    High temperature operation of an electrically driven single photon emitter based on a single epitaxial quantum dot is reported. CdSe/ZnSSe/MgS quantum dots are embedded into a p-i-n diode architecture providing almost background free excitonic and biexcitonic electroluminescence from individual quantum dots through apertures in the top contacts. Clear antibunching with g{sup 2}(??=?0)?=?0.28??0.20 can be tracked up to T?=?200?K, representing the highest temperature for electrically triggered single photon emission from a single quantum dot device.

  14. Influence of the thickness of a crystal on the electrical characteristics of Cd(Zn)Te detectors

    SciTech Connect (OSTI)

    Sklyarchuk, V.; Fochuk, p.; Rarenko, I.; Zakharuk, Z.; Sklyarchuk, O. F.; Bolotnikov, A. E.; James, R. B.

    2015-08-01

    We studied the electrical characteristics of Cd(Zn)Te detectors with rectifying contacts and varying thicknesses, and established that their geometrical dimensions affect the measured electrical properties. We found that the maximum value of the operating-bias voltage and the electric field in the detector for acceptable values of the dark current can be achieved when the crystal has an optimum thickness. This finding is due to the combined effect of generation-recombination in the space-charge region and space-charge limited currents (SCLC).

  15. Study of asymmetries of Cd(Zn)Te devices investigated using photo-induced current transient spectroscopy, Rutherford backscattering, surface photo-voltage spectroscopy, and gamma ray spectroscopies

    SciTech Connect (OSTI)

    Crocco, J.; Bensalah, H.; Zheng, Q.; Dieguez, E.; Corregidor, V.; Avles, E.; Castaldini, A.; Fraboni, B.; Cavalcoli, D.; Cavallini, A.; Vela, O.

    2012-10-01

    Despite these recent advancements in preparing the surface of Cd(Zn)Te devices for detector applications, large asymmetries in the electronic properties of planar Cd(Zn)Te detectors are common. Furthermore, for the development of patterned electrode geometries, selection of each electrode surface is crucial for minimizing dark current in the device. This investigation presented here has been carried out with three objectives. Each objective is oriented towards establishing reliable methods for the selection of the anode and cathode surfaces independent of the crystallographic orientation. The objectives of this study are (i) investigate how the asymmetry in I-V characteristics of Cd(Zn)Te devices may be associated with the TeO2 interfacial layer using Rutherford backscattering to study the structure at the Au-Cd(Zn)Te interface, (ii) develop an understanding of how the concentration of the active traps in Cd(Zn)Te varies with the external bias, and (iii) propose non-destructive methods for selection of the anode and cathode which are independent of crystallographic orientation. The spectroscopic methods employed in this investigation include Rutherford backscattering spectroscopy, photo-induced current transient spectroscopy, and surface photo-voltage spectroscopy, as well as gamma ray spectroscopy to demonstrate the influence on detector properties.

  16. Voltage-induced electroluminescence characteristics of hybrid light-emitting diodes with CdSe/Cd/ZnS core-shell nanoparticles embedded in a conducting polymer on plastic substrates

    SciTech Connect (OSTI)

    Kwak, Kiyeol; Cho, Kyoungah, E-mail: chochem@korea.ac.kr, E-mail: sangsig@korea.ac.kr; Kim, Sangsig, E-mail: chochem@korea.ac.kr, E-mail: sangsig@korea.ac.kr [Department of Electrical Engineering, Korea University, Seoul 136-713 (Korea, Republic of)] [Department of Electrical Engineering, Korea University, Seoul 136-713 (Korea, Republic of)

    2014-03-10

    We investigate the electroluminescence (EL) characteristics of a hybrid light-emitting diode (HyLED) with an emissive layer comprised of CdSe/Cd/ZnS core-shell nanoparticles (NPs) embedded in poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) on a plastic substrate. The EL characteristics change dramatically with increasing of the biased voltage. At low voltages, recombination of electrons and holes occurs only in the PFO film because of poor charge transfer in the PFO-CdSe/Cd/ZnS NPs composite film, while the color of the light-emitting from the HyLED changes from blue to red as the biased voltage increases from 7.5 to 17.5?V. We examine and discuss the mechanism of this color tunability.

  17. TiO2 Nanotubes with a ZnO Thin Energy Barrier for Improved Current Efficiency of CdSe Quantum-Dot-Sensitized Solar Cells

    SciTech Connect (OSTI)

    Lee, W.; Kang, S. H.; Kim, J. Y.; Kolekar, G. B.; Sung, Y. E.; Han, S. H.

    2009-01-01

    This paper reports the formation of a thin ZnO energy barrier between a CdSe quantum dot (Q dots) sensitizer and TiO{sub 2} nanotubes (TONTs) for improved current efficiency of Q dot-sensitized solar cells. The formation of a ZnO barrier between TONTs and the Q dot sensitizer increased the short-circuit current under illumination and also reduced the dark current in a dark environment. The power conversion efficiency of Q dot-sensitized TONT solar cells increased by 25.9% in the presence of the ZnO thin layer due to improved charge-collecting efficiency and reduced recombination.

  18. Effects of chemo-mechanical polishing on CdZnTe X-ray and gamma-ray detectors

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Egarievwe, Stephen E.; Hossain, Anwar; Okwechime, Ifechukwude O.; Gul, Rubi; James, Ralph B.

    2015-06-23

    Here, mechanically polishing cadmium zinc telluride (CdZnTe) wafers for x-ray and gamma-ray detectors often is inadequate in removing surface defects caused by cutting them from the ingots. Fabrication-induced defects, such as surface roughness, dangling bonds, and nonstoichiometric surfaces, often are reduced through polishing and etching the surface. In our earlier studies of mechanical polishing with alumina powder, etching with hydrogen bromide in hydrogen peroxide solution, and chemomechanical polishing with bromine–methanol–ethylene glycol solution, we found that the chemomechanical polishing process produced the least surface leakage current. In this research, we focused on using two chemicals to chemomechanically polish CdZnTe wafers aftermore » mechanical polishing, viz. bromine–methanol–ethylene glycol (BME) solution, and hydrogen bromide (HBr) in a hydrogen peroxide and ethylene–glycol solution. We used x-ray photoelectron spectroscopy (XPS), current–voltage (I–V) measurements, and Am-241 spectral response measurements to characterize and compare the effects of each solution. The results show that the HBr-based solution produced lower leakage current than the BME solution. Results from using the same chemomechanical polishing solution on two samples confirmed that the surface treatment affects the measured bulk current (a combination of bulk and surface currents). XPS results indicate that the tellurium oxide to tellurium peak ratios for the mechanical polishing process were reduced significantly by chemomechanical polishing using the BME solution (78.9% for Te 3d5/2O2 and 76.7% for Te 3d3/2O2) compared with the HBr-based solution (27.6% for Te 3d5/2O2 and 35.8% for Te 3d3/2O2). Spectral response measurements showed that the 59.5-keV peak of Am-241 remained under the same channel number for all three CdZnTe samples. While the BME-based solution gave a better performance of 7.15% full-width at half-maximum (FWHM) compared with 7.59% FWHM for the HBr-based solution, the latter showed a smaller variation in performance of 0.39% FWHM over 7 days compared with 0.69% for the BME-based solution.« less

  19. Use of high-granularity position sensing to correct response non-uniformities of CdZnTe detectors

    SciTech Connect (OSTI)

    Bolotnikov, A. E. Camarda, G. S.; Cui, Y.; De Geronimo, G.; Fried, J.; Hossain, A.; Mahler, G.; Maritato, M.; Marshall, M.; Roy, U.; Vernon, E.; Yang, G.; James, R. B.; Lee, K.; Petryk, M.

    2014-06-30

    CdZnTe (CZT) is a promising medium for room-temperature gamma-ray detectors. However, the low production yield of acceptable quality crystals hampers the use of CZT detectors for gamma-ray spectroscopy. Significant efforts have been directed towards improving quality of CZT crystals to make them generally available for radiation detectors. Another way to address this problem is to implement detector designs that would allow for more accurate and predictable correction of the charge loss associated with crystal defects. In this work, we demonstrate that high-granularity position-sensitive detectors can significantly improve the performance of CZT detectors fabricated from CZT crystals with wider acceptance boundaries, leading to an increase of their availability and expected decrease in cost.

  20. Effect of large additions of Cd, Pb, Cr, Zn, to cement raw meal on the composition and the properties of the clinker and the cement

    SciTech Connect (OSTI)

    Murat, M.; Sorrentino, F.

    1996-03-01

    The utilization of hydraulic binders to solidify and to stabilize industrial wastes and municipal garbage is presently recognized as one of the solutions to the problem of environment protection. Te addition of important quantities of Cd, Pb, Cr, Zn to raw meals of Portland and calcium aluminate cement modifies the mineralogical composition and the properties of the final cement. Portland cement can absorb a large amount of Cd and Zn. This absorption leads to an increase of setting time and a decrease of strengths of the cement. It also can trap chromium with a short setting time and high strengths. Calcium aluminate cements easily trap Cd and Cr with a delayed setting and good strength but also Pb with normal setting time and strengths. Large quantities of zinc oxide have a deleterious effect on calcium aluminate strengths.

  1. Real-structure effects: Band gaps of Mg_xZn_{1-x}O, Cd_xZn_{1-x}O, and n-type ZnO from ab-initio calculations

    SciTech Connect (OSTI)

    Schleife, A; Bechstedt, F

    2012-02-15

    Many-body perturbation theory is applied to compute the quasiparticle electronic structures and the optical-absorption spectra (including excitonic effects) for several transparent conducting oxides. We discuss HSE+G{sub 0}W{sub 0} results for band structures, fundamental band gaps, and effective electron masses of MgO, ZnO, CdO, SnO{sub 2}, SnO, In{sub 2}O{sub 3}, and SiO{sub 2}. The Bethe-Salpeter equation is solved to account for excitonic effects in the calculation of the frequency-dependent absorption coefficients. We show that the HSE+G{sub 0}W{sub 0} approach and the solution of the Bethe-Salpeter equation are very well-suited to describe the electronic structure and the optical properties of various transparent conducting oxides in good agreement with experiment.

  2. MgSe/ZnSe/CdSe coupled quantum wells grown on InP substrate with intersubband absorption covering 1.55??m

    SciTech Connect (OSTI)

    Chen, Guopeng; Shen, Aidong; De Jesus, Joel; Tamargo, Maria C.

    2014-12-08

    The authors report the observation of intersubband (ISB) transitions in the optical communication wavelength region in MgSe/ZnSe/CdSe coupled quantum wells (QWs). The coupled QWs were grown on InP substrates by molecular beam epitaxy. By inserting ZnSe layers to compensate the strain, samples with high structural quality were obtained, as indicated by well resolved satellite peaks in high-resolution x-ray diffraction. The observed ISB transition energies agree well with the calculated values.

  3. CdSe/ZnSe quantum dot with a single Mn{sup 2+} ionA new system for a single spin manipulation

    SciTech Connect (OSTI)

    Smole?ski, T.

    2015-03-21

    We present a magneto-optical study of individual self-assembled CdSe/ZnSe quantum dots doped with single Mn{sup 2+} ions. Properties of the studied dots are analyzed analogously to more explored system of Mn-doped CdTe/ZnTe dots. Characteristic sixfold splitting of the neutral exciton emission line as well as its evolution in the magnetic field are described using a spin Hamiltonian model. Dynamics of both exciton recombination and Mn{sup 2+} spin relaxation are extracted from a series of time-resolved experiments. Presence of a single dopant is shown not to affect the average excitonic lifetime measured for a number of nonmagnetic and Mn-doped dots. On the other hand, non-resonant pumping is demonstrated to depolarize the Mn{sup 2+} spin in a quantum dot placed in external magnetic field. This effect is utilized to determine the ion spin relaxation time in the dark.

  4. In situ capping for size control of monochalcogenides (ZnS, CdS, and SnS) nanocrystals produced by anaerobic metal-reducing bacteria

    SciTech Connect (OSTI)

    Jang, Gyoung Gug; Jacobs, Christopher B; Ivanov, Ilia N; Joshi, Pooran C; Meyer III, Harry M; Kidder, Michelle; Armstrong, Beth L; Datskos, Panos G; Graham, David E; Moon, Ji Won

    2015-01-01

    Metal monochalcogenide quantum dot nanocrystals of ZnS, CdS and SnS were prepared by anaerobic, metal-reducing bacteria using in situ capping by oleic acid or oleylamine. The capping agent preferentially adsorbs on the surface of the nanocrystal, suppressing the growth process in the early stages, thus leading to production of nanocrystals with a diameter of less than 5 nm.

  5. In situ capping for size control of monochalcogenides (ZnS, CdS, and SnS) nanocrystals produced by anaerobic metal-reducing bacteria

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jang, Gyoung Gug; Jacobs, Christopher B.; Ivanov, Ilia N.; Joshi, Pooran C.; Meyer, III, Harry M.; Kidder, Michelle; Armstrong, Beth L.; Datskos, Panos G.; Graham, David E.; Moon, Ji -Won

    2015-07-24

    Metal monochalcogenide quantum dot nanocrystals of ZnS, CdS and SnS were prepared by anaerobic, metal-reducing bacteria using in situ capping by oleic acid or oleylamine. Furthermore, the capping agent preferentially adsorbs on the surface of the nanocrystal, suppressing the growth process in the early stages, thus leading to production of nanocrystals with a diameter of less than 5 nm.

  6. Magnetooptical study of CdSe/ZnMnSe semimagnetic quantum-dot ensembles with n-type modulation doping

    SciTech Connect (OSTI)

    Reshina, I. I. Ivanov, S. V.

    2014-12-15

    Magnetic and polarization investigations of the photoluminescence and resonant electron spin-flip Raman scattering in ensembles of self-organized CdSe/ZnMnSe semimagnetic quantum dots with n-type modulation doping are carried out. It is demonstrated that exciton transitions contribute to the photoluminescence band intensity, along with the transitions of trions in the singlet state. In the Hanle-effect measurements, negative circular polarization in zero magnetic field is observed, which is related to the optical orientation of a trion heavy hole. The lifetime and spin-relaxation time of a heavy hole are estimated as ?3 and ?1 ps, respectively. Such short times are assumed to be due to Auger recombination with the excitation of an intrinsic transition in a Mn{sup 2+} ion. Investigations of the photoluminescence-maximum intensity and shift in a longitudinal magnetic field at the ?{sup ?}?{sup +} and ?{sup ?}?{sup ?} polarizations reveal the pronounced spin polarization of electrons. Under resonant excitation conditions, a sharp increase in the photoluminescence-band maximum intensity at ?{sup ?} excitation polarization over the ?{sup +} one is observed. The Raman scattering peak at the electron spin-flip transition is observed upon resonant excitation in a transverse magnetic field in crossed linear polarizations. This peak is shown to be a Brillouin function of a magnetic field.

  7. CdSe/ZnS quantum dots based electrochemical immunoassay for the detection of phosphorylated bovine serum albumin

    SciTech Connect (OSTI)

    Pinwattana, Kulwadee; Wang, Jun; Lin, Chiann Tso; Wu, Hong; Du, Dan; Lin, Yuehe; Chailapakul, Orawon

    2010-11-15

    A CdSe/ZnS quantum dot (QD) based electrochemical immunoassay of phosphorylated bovine serum albumin as a protein biomarker is presented. The QDs were used as labels and were conjugated with the secondary anti-phosphoserine antibody in a heterogeneous sandwich immunoassay. First, the primary BSA antibody was immobilized on polystyrene microwells, followed by the addition of BSA-OP. After that, the QD-labeled anti-phosphoserine antibody was added into microwells for immunorecognition. Finally, the bound QD was dissolved in an acid-dissolution step and was detected by electrochemical stripping analysis. The measured current responses were proportional to the concentration of BSA-OP. Under optimal conditions, the voltammetric response was linear over the range of 0.5 - 500 ng mL-1 of BSA-OP, with a detection limit of 0.5 ng mL-1 at a deposition potential of -1.2 V for 120 s. It also shows good reproducibility with a relative standard deviation of 8.6% of six times determination of 25 ng mL-1 of BSA-OP. This QD-based electrochemical immunoassay offers great promise for simple and cost-effective analysis of protein biomarkers.

  8. Structural, elastic, electronic and phonon properties of SnX{sub 2}O{sub 4} (X=Mg, Zn, Cd) spinel from density functional theory

    SciTech Connect (OSTI)

    U?ur, Gkay; Candan, Abdullah

    2014-10-06

    First-principle calculations of structural, electronic, elastic and phonon properties of SnMg{sub 2}O{sub 4}, SnZn{sub 2}O{sub 4} and SnCd{sub 2}O{sub 4} compounds are presented, using the pseudo-potential plane waves approach based on density functional theory (DFT) within the generalized gradient approximation (GGA). The computed ground state structural parameters, i.e. lattice constants, internal free parameter and bulk modulus are in good agreement with the available theoretical results. Our calculated elastic constants are indicative of stability of SnX{sub 2}O{sub 4} (X=Mg, Zn, Cd) compounds in the spinel structure. The partial density of states (PDOS) of these compounds is in good agreement with the earlier ab-initio calculations. The phonon dispersion relations were calculated using the direct method. Phonon dispersion results indicate that SnZn{sub 2}O{sub 4} is dynamically stable, while SnMg{sub 2}O{sub 4} and SnCd{sub 2}O{sub 4} are unstable.

  9. Preparation of water soluble L-arginine capped CdSe/ZnS QDs and their interaction with synthetic DNA: Picosecond-resolved FRET study

    SciTech Connect (OSTI)

    Giri, Anupam; Goswami, Nirmal; Lemmens, Peter; Pal, Samir Kumar

    2012-08-15

    Graphical abstract: Frster resonance energy transfer (FRET) studies on the interaction of water soluble arginine-capped CdSe/ZnS QDs with ethidium bromide (EB) labeled synthetic dodecamer DNA. Highlights: ? We have solubilized CdSe/ZnS QD in water replacing their TOPO ligand by L-arginine. ? We have studied arginine@QDDNA interaction using FRET technique. ? Arginine@QDs act as energy donor and ethidium bromide-DNA acts as energy acceptor. ? We have applied a kinetic model to understand the kinetics of energy transfer. ? Circular dichroism studies revealed negligible perturbation in the DNA B-form in the arg@QD-DNA complex. -- Abstract: We have exchanged TOPO (trioctylphosphine oxide) ligand of CdSe/ZnS core/shell quantum dots (QDs) with an amino acid L-arginine (Arg) at the toluene/water interface and eventually rendered the QDs from toluene to aqueous phase. We have studied the interaction of the water soluble Arg-capped QDs (energy donor) with ethidium (EB) labeled synthetic dodecamer DNA (energy acceptor) using picoseconds resolved Frster resonance energy transfer (FRET) technique. Furthermore, we have applied a model developed by M. Tachiya to understand the kinetics of energy transfer and the distribution of acceptor (EB-DNA) molecules around the donor QDs. Circular dichroism (CD) studies revealed a negligible perturbation in the native B-form structure of the DNA upon interaction with Arg-capped QDs. The melting and the rehybridization pathways of the DNA attached to the QDs have been monitored by the CD which reveals hydrogen bonding is the associative mechanism for interaction between Arg-capped QDs and DNA.

  10. Boundary Entropy Can Increase Under Bulk RG Flow (Journal Article...

    Office of Scientific and Technical Information (OSTI)

    Boundary Entropy Can Increase Under Bulk RG Flow Citation Details In-Document Search Title: Boundary Entropy Can Increase Under Bulk RG Flow You are accessing a document from ...

  11. Zinc concentration effect on structural, optical and electrical properties of Cd{sub 1?x}Zn{sub x}Se thin films

    SciTech Connect (OSTI)

    Akaltun, Yunus; Y?ld?r?m, M. Ali; Ate?, Aytun; Y?ld?r?m, Muhammet

    2012-11-15

    Highlights: ? Cd{sub 1?x}Zn{sub x}Se thin films were deposited using SILAR method. ? The electron effective mass, refractive index, dielectric constant values were calculated by using the energy bandgap values as a function of the zinc concentration (x). ? The resistivity and activation energy changed as a function of the zinc concentration (x). -- Abstract: Cd{sub 1?x}Zn{sub x}Se thin films with different compositions (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were deposited on glass substrates using successive ionic layer adsorption and reaction (SILAR) method at room temperature and ambient pressure. The zinc concentration (x) effect on the structural, morphological, optical and electrical properties of Cd{sub 1?x}Zn{sub x}Se thin films were investigated. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies showed that all the films exhibited polycrystalline nature and were covered well on glass substrates. The energy dispersive X-ray (EDAX) analysis confirmed nearly stoichiometric deposition of the films. The energy bandgap values were changed from 1.99 to 2.82 eV depending on the zinc concentration. Bowing parameter was calculated as 0.08 eV. The electron effective mass (m{sub e}*/m{sub o}), refractive index (n), optical static and high frequency dielectric constants (?{sub o}, ?{sub ?}) values were calculated by using the energy bandgap values as a function of the zinc concentration. The resistivity values of the films changed between 10{sup 5} and 10{sup 7} ? cm with increasing zinc concentration at room temperature.

  12. Charge trapping and de-trapping in isolated CdSe/ZnS nanocrystals under an external electric field: Indirect evidence for a permanent dipole moment

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zang, Huidong; Cristea, Mihail; Shen, Xuan; Liu, Mingzhao; Camino, Fernando; Cotlet, Mircea

    2015-08-05

    Single nanoparticle studies of charge trapping and de-trapping in core/shell CdSe/ZnS nanocrystals incorporated into an insulating matrix and subjected to an external electric field demonstrate the ability to reversibly modulate the exciton dynamics and photoluminescence blinking while providing indirect evidence for the existence of a permanent ground state dipole moment in such nanocrystals. A model assuming the presence of energetically deep charge traps physically aligned along the direction of the permanent dipole is proposed in order to explain the dynamics of nanocrystal blinking in the presence of a permanent dipole moment.

  13. Quantum-dot light-emitting diodes utilizing CdSe/ZnS nanocrystals embedded in TiO{sub 2} thin film

    SciTech Connect (OSTI)

    Kang, Seung-Hee; Kumar, Ch. Kiran; Kim, Eui-Tae; Lee, Zonghoon; Kim, Kyung-Hyun; Huh, Chul

    2008-11-10

    Quantum-dot (QD) light-emitting diodes (LEDs) are demonstrated on Si wafers by embedding core-shell CdSe/ZnS nanocrystals in TiO{sub 2} thin films via plasma-enhanced metallorganic chemical vapor deposition. The n-TiO{sub 2}/QDs/p-Si LED devices show typical p-n diode current-voltage and efficient electroluminescence characteristics, which are critically affected by the removal of QD surface ligands. The TiO{sub 2}/QDs/Si system we presented can offer promising Si-based optoelectronic and electronic device applications utilizing numerous nanocrystals synthesized by colloidal solution chemistry.

  14. Fluorescent CdSe/ZnS nanocrystal-peptide conjugates for long-term, nontoxic imaging and nuclear targeting in living cells

    SciTech Connect (OSTI)

    Chen, Fanqing; Gerion, Daniele

    2004-06-14

    One of the biggest challenges in cell biology is the imaging of living cells. For this purpose, the most commonly used visualization tool is fluorescent markers. However, conventional labels, such as organic fluorescent dyes or green fluorescent proteins (GFP), lack the photostability to allow the tracking of cellular events that happen over minutes to days. In addition, they are either toxic to cells (dyes), or difficult to construct and manipulate (GFP). We report here the use of a new class of fluorescent labels, silanized CdSe/ZnS nanocrystal-peptide conjugates, for imaging the nuclei of living cells. CdSe/ZnS nanocrystals, or so called quantum dots (qdots), are extremely photostable, and have been used extensively in cellular imaging of fixed cells. However, most of the studies about living cells so far have been concerned only with particle entry into the cytoplasm or the localization of receptors on the cell membrane. Specific targeting of qdots to the nucleus of living cells ha s not been reported in previous studies, due to the lack of a targeting mechanism and proper particle size. Here we demonstrate for the first time the construction of a CdSe/ZnS nanocrystal-peptide conjugate that carries the SV40 large T antigen nuclear localization signal (NLS), and the transfection of the complex into living cells. By a novel adaptation of commonly used cell transfection techniques for qdots, we were able to introduce and retain the NLS-qdots conjugate in living cells for up to a week without detectable negative cellular effects. Moreover, we can visualize the movement of the CdSe/ZnS nanocrystal-peptide conjugates from cytoplasm to the nucleus, and the accumulation of the complex in the cell nucleus, over a long observation time period. This report opens the door for using qdots to visualize long-term biological events that happen in the cell nucleus, and provides a new nontoxic, long-term imaging platform for cell nuclear processes.

  15. Photophysics of (CdSe)ZnS Colloidal Quantum Dots in an Aqueous Environment Stabilized with Amino Acids and Genetically-Modified Proteins

    SciTech Connect (OSTI)

    Ai, X.; Xu, Q.; Jones, M.; Song, Q.; Ding, S.-Y.; Ellingson, R. J.; Himmel, M.; Rumbles, G.

    2007-01-01

    Using a combination of two amino acids, histidine and N-acetyl-cysteine, to replace the original organic capping groups of (CdSe)ZnS quantum dots, water-soluble and highly luminescent (CdSe)ZnS quantum dots have been successfully prepared at pH 8. Characterization by steady-state and time-resolved photoluminescence spectroscopy, and transient absorption spectroscopy, demonstrate that the electronic properties of these quantum dots exceed those of the original as-synthesized samples dissolved in a more-conventional organic solvent. Furthermore, these amino acid-stabilized quantum dots have been assembled onto a cellulose substrate via cellulose binding proteins that specifically bind to cellulose and was genetically engineered to harbor dual hexahistidine tags at the N- and C-termini to confer binding with the zinc(II) on the quantum dot surface. The spectroscopic measurements show that the protein-bound quantum dots continue to retain their desirable electronic properties when bound on the substrate. Meanwhile, the specific and very selective binding properties of the proteins have remained effective. (1)Select optimal greenhouse gas (GHG) and petroleum reduction strategies for each fleet location, (2)Meet or exceed Federal fleet GHG and petroleum reduction requirements outlined in the Guidance, (3)Acquire vehicles to support these strategies while minimizing fleet size and vehicle miles traveled (VMT), (4)Refine strategies based on agency performance.

  16. High temperature thermoelectric properties of the solid-solution zintl phase Eu₁₁Cd6-xZnxSb₁₂

    SciTech Connect (OSTI)

    Kazem, Nasrin; Hurtado, Antonio; Sui, Fan; Ohno, Saneyuki; Zevalkink, Alexandra; Snyder, Jeffrey G.; Kauzlarich, Susan M.

    2015-08-24

    Solid-solution Zintl compounds with the formulaEu₁₁Cd6-xZnxSb₁₂ have been synthesized from the elements as single crystals using a tin flux according to the stoichiometry Eu:Cd:Zn:Sb:Sn of 11:6–xp:xp:12:30 with xp = 0, 1, 2, 3, 4, 5, and 6, where xp is the preparative amount of Zn employed in the reaction. The crystal structures and the compositions were established by single-crystal as well as powder X-ray diffraction and wavelength-dispersive X-ray analysis measurements. The title solid-solution Zintl compounds crystallize isostructurally in the centrosymmetric monoclinic space group C 2/m (No. 12, Z = 2) as the Sr₁₁Cd₆Sb₁₂ structure type (Pearson symbol mC58). There is a miscibility gap at 3 ≤ xp ≤ 4 where the major product crystallizes in a disordered structure related to the Ca₉Mn₄Bi₉ structure type; otherwise, for all other compositions, the Sr₁₁Cd₆Sb₁₂ structure is the majority phase. Eu₁₁Cd₆Sb₁₂ shows lower lattice thermal conductivity relative to Eu₁₁Zn₆Sb₁₂ consistent with its higher mean atomic weight, and as anticipated, the solid-solution samples of Eu₁₁Cd6–xZnxSb₁₂ have effectively reduced lattice thermal conductivities relative to the end member compounds. Eu₁₁̣̣₀(1)Cd₄̣̣₅(2)Zn₁̣̣₅(2)Sb₁₂̣̣₀(1) exhibits the highest zT value of >0.5 at around 800 K which is twice as large as the end member compounds.

  17. Fluorescence resonance energy transfer measured by spatial photon migration in CdSe-ZnS quantum dots colloidal systems as a function of concentration

    SciTech Connect (OSTI)

    Azevedo, G.; Monte, A. F. G.; Reis, A. F.; Messias, D. N.

    2014-11-17

    The study of the spatial photon migration as a function of the concentration brings into attention the problem of the energy transfer in quantum dot embedded systems. By measuring the photon propagation and its spatial dependence, it is possible to understand the whole dynamics in a quantum dot system, and also improve their concentration dependence to maximize energy propagation due to radiative and non-radiative processes. In this work, a confocal microscope was adapted to scan the spatial distribution of photoluminescence from CdSe-ZnS core-shell quantum dots in colloidal solutions. The energy migration between the quantum dots was monitored by the direct measurement of the photon diffusion length, according to the diffusion theory. We observed that the photon migration length decreases by increasing the quantum dot concentration, this kind of behavior has been regarded as a signature of Frster resonance energy transfer in the system.

  18. Boundary Entropy Can Increase Under Bulk RG Flow (Journal Article) |

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Boundary Entropy Can Increase Under Bulk RG Flow Citation Details In-Document Search Title: Boundary Entropy Can Increase Under Bulk RG Flow The boundary entropy log(g) of a critical one-dimensional quantum system (or two-dimensional conformal field theory) is known to decrease under renormalization group (RG) flow of the boundary theory. We study instead the behavior of the boundary entropy as the bulk theory flows between two nearby critical points. We use conformal

  19. Ordering mechanism of stacked CdSe/ZnS{sub x}Se{sub 1-x} quantum dots: A combined reciprocal-space and real-space approach

    SciTech Connect (OSTI)

    Schmidt, Th.; Roventa, E.; Clausen, T.; Flege, J. I.; Alexe, G.; Rosenauer, A.; Hommel, D.; Falta, J.; Bernstorff, S.; Kuebel, C.

    2005-11-15

    The vertical and lateral ordering of stacked CdSe quantum dot layers embedded in ZnS{sub x}Se{sub 1-x} has been investigated by means of grazing incidence small angle x-ray scattering and transmission electron microscopy. Different growth parameters have been varied in order to elucidate the mechanisms leading to quantum dot correlation. From the results obtained for different numbers of quantum dot layers, we conclude on a self-organized process which leads to increasing ordering for progressive stacking. The dependence on the spacer layer thickness indicates that strain induced by lattice mismatch drives the ordering process, which starts to break down for too thick spacer layers in a thickness range from 45 to 80 A. Typical quantum dot distances in a range from about 110 to 160 A have been found. A pronounced anisotropy of the quantum dot correlation has been observed, with the strongest ordering along the [110] direction. Since an increased ordering is found with increasing growth temperature, the formation of stacking faults as an additional mechanism for quantum dot alignment can be ruled out.

  20. Determining the exact number of dye molecules attached to colloidal CdSe/ZnS quantum dots in Frster resonant energy transfer assemblies

    SciTech Connect (OSTI)

    Kaiser, Uwe; Jimenez de Aberasturi, Dorleta; Vzquez-Gonzlez, Margarita; Carrillo-Carrion, Carolina; Niebling, Tobias; Parak, Wofgang J.; Heimbrodt, Wolfram

    2015-01-14

    Semiconductor quantum dots functionalized with organic dye molecules are important tools for biological sensor applications. Energy transfer between the quantum dot and the attached dyes can be utilized for sensing. Though important, the determination of the real number of dye molecules attached per quantum dot is rather difficult. In this work, a method will be presented to determine the number of ATTO-590 dye molecules attached to CdSe/ZnS quantum dots based on time resolved spectral analysis. The energy transfer from the excited quantum dot to the attached ATTO-590 dye leads to a reduced lifetime of the quantum dot's excitons. The higher the concentration of dye molecules, the shorter the excitonic lifetime becomes. However, the number of dye molecules attached per quantum dot will vary. Therefore, for correctly explaining the decay of the luminescence upon photoexcitation of the quantum dot, it is necessary to take into account the distribution of the number of dyes attached per quantum dot. A Poisson distribution of the ATTO-590 dye molecules not only leads to excellent agreement between experimental and theoretical decay curves but also additionally yields the average number of dye molecules attached per quantum dot. In this way, the number of dyes per quantum dot can be conveniently determined.

  1. RG&E (Electric)- Commercial and Industrial Efficiency Program

    Broader source: Energy.gov [DOE]

    NYSEG and RG&E offer rebates to non-residential customers installing energy efficient equipment that have an electricity Systems Benefits Charge (SBC) included in their energy bills. Both...

  2. RG&E (Gas)- Commercial and Industrial Efficiency Program

    Broader source: Energy.gov [DOE]

    NYSEG and RG&E offer rebates to non-residential customers installing energy efficiency equipment who pay a natural gas Systems Benefits Charge (SBC). Both prescriptive rebates and custom...

  3. Bright three-band white light generated from CdSe/ZnSe quantum dot-assisted Sr{sub 3}SiO{sub 5}:Ce{sup 3+},Li{sup +}-based white light-emitting diode with high color rendering index

    SciTech Connect (OSTI)

    Jang, Ho Seong; Kwon, Byoung-Hwa; Jeon, Duk Young; Yang, Heesun

    2009-10-19

    In this study, bright three-band white light was generated from the CdSe/ZnSe quantum dot (QD)-assisted Sr{sub 3}SiO{sub 5}:Ce{sup 3+},Li{sup +}-based white light-emitting diode (WLED). The CdSe/ZnSe core/shell structure was confirmed by energy dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy. The CdSe/ZnSe QDs showed high quantum efficiency (79%) and contributed to the high luminous efficiency ({eta}{sub L}) of the fabricated WLED. The WLED showed bright natural white with excellent color rendering property ({eta}{sub L}=26.8 lm/W, color temperature=6140 K, and color rendering index=85) and high stability against the increase in forward bias currents from 20 to 70 mA.

  4. Five new Zn(II) and Cd(II) coordination polymers constructed by 3,5-bis-oxyacetate-benzoic acid: Syntheses, crystal structures, network topologies and luminescent properties

    SciTech Connect (OSTI)

    Jiang Xianrong; Yuan Hongyan; Feng Yunlong

    2012-07-15

    Five Zn(II) and Cd(II) coordination polymers, [Zn{sub 2}(BOABA)(bpp)(OH)]{center_dot}0.5H{sub 2}O (1), [Cd{sub 3}(BOABA){sub 2}(bpp){sub 2}(H{sub 2}O){sub 6}]{center_dot}2H{sub 2}O (2), [Cd{sub 3}(BOABA){sub 2}(2,2 Prime -bipy){sub 3}(H{sub 2}O){sub 4}]{center_dot}5.5H{sub 2}O (3), [CdNa(BOABA)(H{sub 2}O)]{sub 2}{center_dot}H{sub 2}O (4) and [Cd{sub 2}(BOABA)(bimb)Cl(H{sub 2}O){sub 2}]{center_dot}H{sub 2}O (5) (H{sub 3}BOABA=3,5-bis-oxyacetate-benzoic acid, bpp=1,3-bi(4-pyridyl)propane, 2,2 Prime -bipy=2,2 Prime -bipyridine, bimb=1,4-bis(imidazol-1 Prime -yl)butane), have been solvothermally synthesized and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra and TG analyses. 1 is an uninodal 4-connected 2D square grid network based on binuclear zinc clusters. 2 is 2D wavelike layer structure and further linked by hydrogen bonds into the final 3D (5,6,6)-connected topology network. 3 is 3-connected 2D topology network and the 2,2 Prime -bipy ligands decorate in two different types. 4 is a (4,8)-connected 2D topology network with heterocaryotic {l_brace}Cd{sub 2}Na{sub 2}{r_brace} clusters and BOABA{sup 3-} ligands. 5 can be rationalized as a (3,10)-connected 3D topology network with tetranuclear {l_brace}Cd{sub 4}Cl{sub 2}{r_brace} clusters and BOABA{sup 3-} ligands. Meanwhile, photoluminescence studies revealed that these five coordination polymers display strong fluorescent emission bands in the solid state at room temperature. - Graphical abstract: Five new d{sup 10} metal(II) coordination polymers based on H{sub 3}BOABA ligand were obtained and characterized. They display different topological structures and luminescent properties. Highlights: Black-Right-Pointing-Pointer Five d{sup 10} metal(II) polymers based on 3,5-bis-oxyacetate-benzoic acid were obtained. Black-Right-Pointing-Pointer The polymers were structurally characterized by single-crystal X-ray diffraction. Black-Right-Pointing-Pointer Polymers 1-5 display different topological structures. Black-Right-Pointing-Pointer They show strong fluorescent emission bands in the solid state.

  5. Synchrotron X-ray 2D and 3D Elemental Imaging of CdSe/ZnS Quantum dot Nanoparticles in Daphnia Magna

    SciTech Connect (OSTI)

    Jackson, B.; Pace, H; Lanzirotti, A; Smith, R; Ranville, J

    2009-01-01

    The potential toxicity of nanoparticles to aquatic organisms is of interest given that increased commercialization will inevitably lead to some instances of inadvertent environmental exposures. Cadmium selenide quantum dots (QDs) capped with zinc sulfide are used in the semiconductor industry and in cellular imaging. Their small size (<10 nm) suggests that they may be readily assimilated by exposed organisms. We exposed Daphnia magna to both red and green QDs and used synchrotron X-ray fluorescence to study the distribution of Zn and Se in the organism over a time period of 36 h. The QDs appeared to be confined to the gut, and there was no evidence of further assimilation into the organism. Zinc and Se fluorescence signals were highly correlated, suggesting that the QDs had not dissolved to any extent. There was no apparent difference between red or green QDs, i.e., there was no effect of QD size. 3D tomography confirmed that the QDs were exclusively in the gut area of the organism. It is possible that the QDs aggregated and were therefore too large to cross the gut wall.

  6. An array of virtual Frisch-grid CdZnTe detectors and a front-end application-specific integrated circuit for large-area position-sensitive gamma-ray cameras

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bolotnikov, A. E.; Ackley, K.; Camarda, G. S.; Cherches, C.; Cui, Y.; De Geronimo, G.; Fried, J.; Hodges, D.; Hossain, A.; Lee, W.; et al

    2015-07-28

    We developed a robust and low-cost array of virtual Frisch-grid CdZnTe (CZT) detectors coupled to a front-end readout ASIC for spectroscopy and imaging of gamma rays. The array operates as a self-reliant detector module. It is comprised of 36 close-packed 6x6x15 mm3 detectors grouped into 3x3 sub-arrays of 2x2 detectors with the common cathodes. The front-end analog ASIC accommodates up to 36 anode and 9 cathode inputs. Several detector modules can be integrated into a single- or multi-layer unit operating as a Compton or a coded-aperture camera. We present the results from testing two fully assembled modules and readout electronics.more » The further enhancement of the arrays’ performance and reduction of their cost are made possible by using position-sensitive virtual Frisch-grid detectors, which allow for accurate corrections of the response of material non-uniformities caused by crystal defects.« less

  7. An array of virtual Frisch-grid CdZnTe detectors and a front-end application-specific integrated circuit for large-area position-sensitive gamma-ray cameras

    SciTech Connect (OSTI)

    Bolotnikov, A. E.; Ackley, K.; Camarda, G. S.; Cherches, C.; Cui, Y.; De Geronimo, G.; Fried, J.; Hodges, D.; Hossain, A.; Lee, W.; Mahler, G.; Maritato, M.; Petryk, M.; Roy, U.; Salwen, C.; Vernon, E.; Yang, G.; James, R. B.

    2015-07-28

    We developed a robust and low-cost array of virtual Frisch-grid CdZnTe (CZT) detectors coupled to a front-end readout ASIC for spectroscopy and imaging of gamma rays. The array operates as a self-reliant detector module. It is comprised of 36 close-packed 6x6x15 mm3 detectors grouped into 3x3 sub-arrays of 2x2 detectors with the common cathodes. The front-end analog ASIC accommodates up to 36 anode and 9 cathode inputs. Several detector modules can be integrated into a single- or multi-layer unit operating as a Compton or a coded-aperture camera. We present the results from testing two fully assembled modules and readout electronics. The further enhancement of the arrays’ performance and reduction of their cost are made possible by using position-sensitive virtual Frisch-grid detectors, which allow for accurate corrections of the response of material non-uniformities caused by crystal defects.

  8. Influence of irradiation with {gamma}-ray photons on the photoluminescence of Cd{sub 0.9}Zn{sub 0.1}Te crystals preliminarily subjected to the intense radiation of a neodymium laser

    SciTech Connect (OSTI)

    Glinchuk, K. D.; Medvid', A. P.; Mychko, A. M.; Naseka, Yu. M.; Prokhorovich, A. V.; Strilchuk, O. M.

    2013-04-15

    The effect of the preliminary treatment of Cd{sub 0.9}Zn{sub 0.1}Te crystals with high-power pulses of neodymium laser radiation (the power density is {<=}1.8 MW/cm{sup 2}, at a wavelength of 532 nm) on the low-temperature (5 K) photoluminescence induced by {gamma}-ray radiation (the dose was {Phi}{sub {gamma}} = 5 kGy) is studied. The luminescence bands are related to radiation-stimulated donor-acceptor pairs, which include shallow neutral donors and neutral cadmium vacancies stimulated by {gamma}-ray irradiation, the transition of free electrons to neutral cadmium vacancies formed by radiation, and the annihilation of excitons bound to the above vacancies. It is shown that, in the crystals preliminarily treated with laser radiation, the intensity of the {gamma}-ray-stimulated luminescence bands is significantly lower than in crystals not subjected to laser radiation. This fact is accounted for by a decrease in the concentration of cadmium vacancies generated by the {gamma}-ray radiation as a result of their annihilation during the course of their interaction with laser-stimulated defects, in particular, as a consequence of their recombination at laser-stimulated interstitial cadmium atoms.

  9. Microsoft Word - RBL_Jan_2009_RG24-13-398.doc

    Office of Legacy Management (LM)

    well Federal RG 24-13-398: http:oil-gas.state.co.uscogisFacilityDetail.asp?facid10310702&... Collected using a temporary valve installed at the output of the separator. ...

  10. Microsoft Word - RBL_Jan_2009_RG13-1-398.doc

    Office of Legacy Management (LM)

    Link to Colorado Oil and Gas Conservation Commission information about well RG 13-1-398: http:oil-gas.... Collected using a temporary valve installed at the output of the separator. ...

  11. CD Templates

    Broader source: Energy.gov [DOE]

    EERE has developed templates for CD labels and CD packages. These can be used for all EERE products. Both templates are available as EPS files, which can be downloaded and edited in a graphics package like Adobe Illustrator.

  12. Ginsenoside Rg3 regulates S-nitrosylation of the NLRP3 inflammasome via suppression of iNOS

    SciTech Connect (OSTI)

    Yoon, Sung-Jin; Park, Jun-Young; Choi, Song; Lee, Jin-Bong; Jung, Haiyoung; Kim, Tae-Don; Yoon, Suk Ran; Choi, Inpyo; Shim, Sungbo; Park, Young-Jun

    2015-08-07

    Ginsenoside Rg3, a specific biological effector, is well-known as a major bioactive ingredient of Panax ginseng. However, its role in the inflammasome activation process remains unclear. In this report, we demonstrate that ginsenosides 20(R)-Rg3 and 20(S)-Rg3 are capable of suppressing both lethal endotoxic shock and the S-nitrosylation of the NLRP3 inflammasome by inhibiting nitric oxide (NO) production through the regulation of inducible nitric oxide synthase (iNOS) expression. In response to lipopolysaccharide (LPS), the reducing effect of 20(S)-Rg3 and 20(R)-Rg3 on nitric oxide led to an increase in the survival time of mice after lethal endotoxin-induced shock, and excess levels of NO inhibited IL-1β production via the S-nitrosylation of the NLRP3 inflammasome. In addition, ginsenosides 20(R)-Rg3 and 20(S)-Rg3 had suppressive effects on the LPS- or UV-irradiation-induced reactive oxygen species (ROS) levels in macrophage and HaCaT cells and thereby prevented apoptosis of spleen cells in mice. Altogether, these results demonstrate that ginsenoside 20(R)-Rg3 and 20(S)-Rg3, a naturally occurring compound, might act as a dual therapeutic regulator for the treatment of inflammatory and oxidative stress-related diseases. - Highlights: • Ginsenosides Rg3 inhibits NO production through the regulation of iNOS expression. • Ginsenosides Rg3 inhibits the S-nitrosylation of the NLRP3 inflammasome. • Ginsenosides Rg3 suppress on the LPS- or UV-irradiation-induced ROS levels in cells.

  13. Electroluminescence of ZnO-based semiconductor heterostructures

    SciTech Connect (OSTI)

    Novodvorskii, O A; Lotin, A A; Panchenko, Vladislav Ya; Parshina, L S; Khaidukov, E V; Zuev, D A; Khramova, O D [Institute on Laser and Information Technologies, Russian Academy of Sciences, Shatura, Moscow Region (Russian Federation)

    2011-01-31

    Using pulsed laser deposition, we have grown n-ZnO/p-GaN, n-ZnO/i-ZnO/p-GaN and n-ZnO/n-Mg{sub 0.2}Zn{sub 0.8}O/i-Cd{sub 0.2}Zn{sub 0.8}O/p-GaN light-emitting diode (LED) heterostructures with peak emission wavelengths of 495, 382 and 465 nm and threshold current densities (used in electroluminescence measurements) of 1.35, 2, and 0.48 A cm{sup -2}, respectively. Because of the spatial carrier confinement, the n-ZnO/n-Mg{sub 0.2}Zn{sub 0.8}O/i-Cd{sub 0.2}Zn{sub 0.8}O/p-GaN double heterostructure LED offers a higher electroluminescence intensity and lower electroluminescence threshold in comparison with the n-ZnO/p-GaN and n-ZnO/i-ZnO/p-GaN LEDs. (lasers)

  14. Electrodeposition of Zn based nanostructure thin films for photovoltaic applications

    SciTech Connect (OSTI)

    Al-Bathi, S. A. M.

    2015-03-30

    We present here a systematic study on the synthesis thin films of various ZnO, CdO, Zn{sub x}Cd{sub 1-x} (O) and ZnTe nanostructures by electrodeposition technique with ZnCl{sub 2,} CdCl{sub 2} and ZnSO{sub 4} solution as starting reactant. Several reaction parameters were examined to develop an optimal procedure for controlling the size, shape, and surface morphology of the nanostructure. The results showed that the morphology of the products can be carefully controlled through adjusting the concentration of the electrolyte. The products present well shaped Nanorods arrays at specific concentration and temperature. UV-VIS spectroscopy and X-ray diffraction results show that the product presents good crystallinity. A possible formation process has been proposed.

  15. ZnCuInS/ZnSe/ZnS Quantum Dot-Based Downconversion Light-Emitting Diodes and Their Thermal Effect

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liu, Wenyan; Zhang, Yu; Ruan, Cheng; Wang, Dan; Zhang, Tieqiang; Feng, Yi; Gao, Wenzhu; Yin, Jingzhi; Wang, Yiding; Riley, Alexis P.; et al

    2015-01-01

    The quantum dot-based light-emitting diodes (QD-LEDs) were fabricated using blue GaN chips and red-, yellow-, and green-emitting ZnCuInS/ZnSe/ZnS QDs. The power efficiencies were measured as 14.0 lm/W for red, 47.1 lm/W for yellow, and 62.4 lm/W for green LEDs at 2.6 V. The temperature effect of ZnCuInS/ZnSe/ZnS QDs on these LEDs was investigated using CIE chromaticity coordinates, spectral wavelength, full width at half maximum (FWHM), and power efficiency (PE). The thermal quenching induced by the increased surface temperature of the device was confirmed to be one of the important factors to decrease power efficiencies while the CIE chromaticity coordinates changed little due to themore » low emission temperature coefficients of 0.022, 0.050, and 0.068 nm/°C for red-, yellow-, and green-emitting ZnCuInS/ZnSe/ZnS QDs. These indicate that ZnCuInS/ZnSe/ZnS QDs are more suitable for downconversion LEDs compared to CdSe QDs.« less

  16. ARM-96-003 UAV Fall 1996 Flight Series Mission Summary RG Ellingson

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    6-003 UAV Fall 1996 Flight Series Mission Summary RG Ellingson Fall 1996 DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately

  17. ARM-96-004 UAV Spring Flight Series Mission Summary RG Ellingson

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    96-004 UAV Spring Flight Series Mission Summary RG Ellingson Spring 1996 DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately

  18. Telescope Guiding with a HyViSI H2RG Used in Guide Mode

    SciTech Connect (OSTI)

    Simms, Lance M.; Figerb, Donald F.; Hanold, Brandon J.; Kahn, Steven M.; Gilmore, D.Kirk

    2010-06-04

    We report on long exposure results obtained with a Teledyne HyViSI H2RG detector operating in guide mode. The sensor simultaneously obtained nearly seeing-limited data while also guiding the Kitt Peak 2.1 m telescope. Results from unguided and guided operation are presented and used to place lower limits on flux/fluence values for accurate centroid measurements. We also report on significant noise reduction obtained in recent laboratory measurements that should further improve guiding capability with higher magnitude stars.

  19. Recognition of the Activated States of G[alpha]13 by the rgRGS Domain of PDZRhoGEF

    SciTech Connect (OSTI)

    Chen, Zhe; Singer, William D.; Danesh, Shahab M.; Sternweis, Paul C.; Sprang, Stephen R.

    2009-12-01

    G12 class heterotrimeric G proteins stimulate RhoA activation by RGS-RhoGEFs. However, p115RhoGEF is a GTPase Activating Protein (GAP) toward G{alpha}13, whereas PDZRhoGEF is not. We have characterized the interaction between the PDZRhoGEF rgRGS domain (PRG-rgRGS) and the alpha subunit of G13 and have determined crystal structures of their complexes in both the inactive state bound to GDP and the active states bound to GDP {center_dot} AlF (transition state) and GTP{gamma}S (Michaelis complex). PRG-rgRGS interacts extensively with the helical domain and the effector-binding sites on G{alpha}13 through contacts that are largely conserved in all three nucleotide-bound states, although PRG-rgRGS has highest affinity to the Michaelis complex. An acidic motif in the N terminus of PRG-rgRGS occupies the GAP binding site of G{alpha}13 and is flexible in the GDP {center_dot} AlF complex but well ordered in the GTPS complex. Replacement of key residues in this motif with their counterparts in p115RhoGEF confers GAP activity.

  20. High Efficiency Single Crystal CdTe Solar Cells: November 19, 2009 - January 31, 2011

    SciTech Connect (OSTI)

    Carmody, M.; Gilmore, A.

    2011-05-01

    The goal of the program was to develop single crystal CdTe-based top cells grown on Si solar cells as a platform for the subsequent manufacture of high efficiency tandem cells for CPV applications. The keys to both the single junction and the tandem junction cell architectures are the ability to grow high quality single-crystal CdTe and CdZnTe layers on p-type Si substrates, to dope the CdTe and CdZnTe controllably, both n and p-type, and to make low resistance ohmic front and back contacts. EPIR demonstrated the consistent MBE growth of CdTe/Si and CdZnTe/Si having high crystalline quality despite very large lattice mismatches; epitaxial CdTe/Si and CdZnTe/Si consistently showed state-of-the-art electron mobilities and good hole mobilities; bulk minority carrier recombination lifetimes of unintentionally p-doped CdTe and CdZnTe grown by MBE on Si were demonstrated to be consistently of order 100 ns or longer; desired n- and p-doping levels were achieved; solar cell series specific resistances <10 ?-cm2 were achieved; A single-junction solar cell having a state-of-the-art value of Voc and a unverified 16.4% efficiency was fabricated from CdZnTe having a 1.80 eV bandgap, ideal for the top junction in a tandem cell with a Si bottom junction.

  1. COL Application Content Guide for HTGRs: Revision to RG 1.206, Part 1 - Status Report

    SciTech Connect (OSTI)

    Wayne Moe

    2012-08-01

    A combined license (COL) application is required by the Nuclear Regulatory Commission (NRC) for all proposed nuclear plants. The information requirements for a COL application are set forth in 10 CFR 52.79, “Contents of Applications; Technical Information in Final Safety Analysis Report.” An applicant for a modular high temperature gas-cooled reactor (HTGR) must develop and submit for NRC review and approval a COL application which conforms to these requirements. The technical information necessary to allow NRC staff to evaluate a COL application and resolve all safety issues related to a proposed nuclear plant is detailed and comprehensive. To this, Regulatory Guide (RG) 1.206, “Combined License Applications for Nuclear Power Plants” (LWR Edition), was developed to assist light water reactor (LWR) applicants in incorporating and effectively formatting required information for COL application review (Ref. 1). However, the guidance prescribed in RG 1.206 presumes a LWR design proposal consistent with the systems and functions associated with large LWR power plants currently operating under NRC license.

  2. Selective Zn2+ sensing using a modified bipyridine complex

    SciTech Connect (OSTI)

    Akula, Mahesh; El-Khoury, Patrick Z.; Nag, Amit; Bhattacharya, Anupam

    2014-06-01

    A novel fluorescent Zn2+ sensor, 4-(pyridin-2-yl)-3H-pyrrolo[2, 3-c]quinoline (PPQ), has been designed, synthesized and characterized by various spectroscopic and analytical techniques. PPQ exhibits superior detection of Zn2+ in the presence of various cations tested, including Cd2+ and Hg2+, via wavelength shifted fluorescence intensity enhancement. The emission wavelength at 500 nm, ensures probable noninterference from cellular components while performing biological applications.

  3. Atom-probe tomographic study of interfaces of Cu{sub 2}ZnSnS{sub 4} photovoltaic cells

    SciTech Connect (OSTI)

    Tajima, S. Asahi, R.; Itoh, T.; Hasegawa, M.; Ohishi, K.; Isheim, D.; Seidman, D. N.

    2014-09-01

    The heterophase interfaces between the CdS buffer layer and the Cu{sub 2}ZnSnS{sub 4} (CZTS) absorption layers are one of the main factors affecting photovoltaic performance of CZTS cells. We have studied the compositional distributions at heterophase interfaces in CZTS cells using three-dimensional atom-probe tomography. The results demonstrate: (a) diffusion of Cd into the CZTS layer; (b) segregation of Zn at the CdS/CZTS interface; and (c) a change of oxygen and hydrogen concentrations in the CdS layer depending on the heat treatment. Annealing at 573?K after deposition of CdS improves the photovoltaic properties of CZTS cells probably because of the formation of a heterophase epitaxial junction at the CdS/CZTS interface. Conversely, segregation of Zn at the CdS/CZTS interface after annealing at a higher temperature deteriorates the photovoltaic properties.

  4. Synthesis of CdSe quantum dots for quantum dot sensitized solar cell

    SciTech Connect (OSTI)

    Singh, Neetu Kapoor, Avinashi; Kumar, Vinod; Mehra, R. M.

    2014-04-24

    CdSe Quantum Dots (QDs) of size 0.85 nm were synthesized using chemical route. ZnO based Quantum Dot Sensitized Solar Cell (QDSSC) was fabricated using CdSe QDs as sensitizer. The Pre-synthesized QDs were found to be successfully adsorbed on front ZnO electrode and had potential to replace organic dyes in Dye Sensitized Solar Cells (DSSCs). The efficiency of QDSSC was obtained to be 2.06 % at AM 1.5.

  5. Improve the open-circuit voltage of ZnO solar cells with inserting ZnS layers by two ways

    SciTech Connect (OSTI)

    Sun, Yunfei; Yang, Jinghai; Yang, Lili; Cao, Jian; Gao, Ming; Zhang, Zhiqiang; Wang, Zhe; Song, Hang

    2013-04-15

    ZnS NPs layers were deposited on ZnO NRs by two different ways. One is spin coating; the other is successive ionic layer adsorption and reaction (SILAR) method. The ZnO NRs/ZnS NPs composites were verified by X-ray diffraction, X-ray photoelectron spectroscopy, and UVvisible spectrophotometer; their morphologies and thicknesses were examined by scanning electron microscopic and transmission electron microscopic images. The CdS quantum dot sensitized solar cells (QDSSCs) were constructed using ZnO NRs/ZnS NPs composites as photoanode and their photovoltaic characteristic was studied by JV curves. The results indicated that the way of SILAR is more beneficial for retarding the back transfer of electrons to CdS and electrolyte than spin coating method. The open-circuit voltage increased to 0.59 V by introducing a ZnS layer through SILAR method. When ZnS NPs layer was deposited for 10 times on ZnO NRs, the conversion efficiency of QDSSC shows ?3.3 folds increments of as-synthesized ZnO solar cell. - Graphical abstract: When ZnO nanorods were deposited by ZnS for 10 times, the conversion efficiency of QDSSC shows ?3.3 folds increments of as-synthesized ZnO solar cell. Highlights: ? ZnS layers were deposited with two different ways. ? The way of SILAR is more beneficial for retarding the back transfer of electrons. ? The open-circuit voltage increased to 0.59 V by introducing a ZnS layer through SILAR method.

  6. https://bluedart.phe.com/owa/?ae=Item&t=IPM.Note&id=RgAAAAA%2f3

    National Nuclear Security Administration (NNSA)

    Phyllis Radack Manager, Regulatory Services 702-295-6582 702-858-5587 (cell) 702-295-7699 ...idRgAAAAA%2f3mOqqZ%2bfSq... 702-858-5587 (cell) 702-295-7699 (fax) From: Morris, Patrick ...

  7. Pulsed laser deposition of Mn doped CdSe quantum dots for improved solar cell performance

    SciTech Connect (OSTI)

    Dai, Qilin; Wang, Wenyong E-mail: jtang2@uwyo.edu; Tang, Jinke E-mail: jtang2@uwyo.edu; Sabio, Erwin M.

    2014-05-05

    In this work, we demonstrate (1) a facile method to prepare Mn doped CdSe quantum dots (QDs) on Zn{sub 2}SnO{sub 4} photoanodes by pulsed laser deposition and (2) improved device performance of quantum dot sensitized solar cells of the Mn doped QDs (CdSe:Mn) compared to the undoped QDs (CdSe). The band diagram of photoanode Zn{sub 2}SnO{sub 4} and sensitizer CdSe:Mn QD is proposed based on the incident-photon-to-electron conversion efficiency (IPCE) data. Mn-modified band structure leads to absorption at longer wavelengths than the undoped CdSe QDs, which is due to the exchange splitting of the CdSe:Mn conduction band by the Mn dopant. Three-fold increase in the IPCE efficiency has also been observed for the Mn doped samples.

  8. Enhanced spontaneous emission of CdSe quantum dots in monolithic II-VI pillar microcavities

    SciTech Connect (OSTI)

    Lohmeyer, H.; Kruse, C.; Sebald, K.; Gutowski, J.; Hommel, D.

    2006-08-28

    The emission properties of CdSe/ZnSe quantum dots in ZnSe-based pillar microcavities are studied. All-epitaxial cavities made of ZnSSe and MgS/ZnCdSe superlattices with a single quantum-dot sheet embedded have been grown by molecular beam epitaxy. Pillar structures with diameters down to 500 nm have been realized by focused-ion-beam etching. A pronounced enhancement of the spontaneous emission rate of quantum dots coupling to the fundamental mode of the cavities is found as evidence for the Purcell effect. The enhancement by a factor of up to 3.8 depends systematically on the pillar diameter and thus on the Purcell factor of the individual pillars.

  9. Optical properties of ZnO/ZnS and ZnO/ZnTe heterostructures forphotovoltaic applications

    SciTech Connect (OSTI)

    Schrier, Joshua; Demchenko, Denis O.; Wang, Lin-Wang; Alivisatos,A. Paul

    2007-05-01

    Although ZnO and ZnS are abundant, stable, environmentallybenign, their band gap energies (3.44 eV, 3.72 eV) are too large foroptimal photovoltaic efficiency. By using band-corrected pseudopotentialdensity-functional theory calculations, we study how the band gap,opticalabsorption, and carrier localization canbe controlled by formingquantum-well like and nanowire-based heterostructures ofZnO/ZnS andZnO/ZnTe. In the case of ZnO/ZnS core/shell nanowires, which can besynthesized using existing methods, we obtain a band gap of 2.07 eV,which corresponds to a Shockley-Quiesser efficiency limitof 23 percent.Based on these nanowire results, we propose that ZnO/ZnScore/shellnanowires can be used as photovoltaic devices with organic polymersemiconductors as p-channel contacts.

  10. Elastic and surface energies: Two key parameters for CdSe quantum dot formation

    SciTech Connect (OSTI)

    Robin, Ivan-Christophe; Andre, Regis; Bougerol, Catherine; Aichele, Thomas; Tatarenko, Serge

    2006-06-05

    The two-dimensional-three-dimensional transition of a strained CdSe layer on (001) ZnSe induced by the use of amorphous selenium is studied. To precisely control the thickness of the CdSe layer, atomic layer epitaxy growth mode is used. Atomic force microscopy and reflection high-energy electron diffraction measurements reveal the formation of CdSe islands when 3 ML (monolayers) of CdSe, corresponding to the critical thickness, are deposited. When only 2.5 ML of CdSe are deposited another relaxation mechanism is observed, leading to the appearance of strong undulations on the surface. For a 3 ML thick CdSe layer, transmission electron microscopy images indicate that the formation of the islands occurs only after the amorphous selenium desorption.

  11. CD-adapco

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    CD-adapco - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Fuel Cycle Defense Waste Management Programs Advanced Nuclear Energy

  12. Effect and optimization of CdS/CdTe interdiffusion on CdTe electrical properties and CdS/CdTe cell performance

    SciTech Connect (OSTI)

    Song, W.; Mao, D.; Kaydanov, V.; Ohno, T.R.; Trefny, J.V.; Levi, D.H.; Johnston, S. McCandless, B.E.

    1999-03-01

    We have investigated the effect of the CdS/CdTe interdiffusion on the properties of the CdTe films and the CdS/CdTe cell performance. Sulfur (S) diffusion into the CdTe films leads to a decreased defect density in the films, improvement of cell performance, and possibly to the increase of the carrier lifetime in the films. Cell performance is improved with the increase of the amount of S in the CdTe films. S diffusion into CdTe also deteriorates the uniformity of the CdS window layers, resulting in worse cell performance. Based on this study, we propose a processing method to improve cell performance. {copyright} {ital 1999 American Institute of Physics.}

  13. Rod consolidation of RG and E's (Rochester Gas and Electric Corporation) spent PWR (pressurized water reactor) fuel

    SciTech Connect (OSTI)

    Bailey, W.J.

    1987-05-01

    The rod consolidation demonstration involved pulling the fuel rods from five fuel assemblies from Unit 1 of RG and E's R.E. Ginna Nuclear Power Plant. Slow and careful rod pulling efforts were used for the first and second fuel assemblies. Rod pulling then proceeded smoothly and rapidly after some minor modifications were made to the UST and D consolidation equipment. The compaction ratios attained ranged from 1.85 to 2.00 (rods with collapsed cladding were replaced by dummy rods in one fuel assembly to demonstrate the 2:1 compaction ratio capability). This demonstration involved 895 PWR fuel rods, among which there were some known defective rods (over 50 had collapsed cladding); no rods were broken or dropped during the demonstration. However, one of the rods with collapsed cladding unexplainably broke during handling operations (i.e., reconfiguration in the failed fuel canister), subsequent to the rod consolidation demonstration. The broken rod created no facility problems; the pieces were encapsulated for subsequent storage. Another broken rod was found during postdemonstration cutting operations on the nonfuel-bearing structural components from the five assemblies; evidence indicates it was broken prior to any rod consolidation operations. During the demonstration, burnish-type lines or scratches were visible on the rods that were pulled; however, experience indicates that such lines are generally produced when rods are pulled (or pushed) through the spacer grids. Rods with collapsed cladding would not enter the funnel (the transition device between the fuel assembly and the canister that aids in obtaining high compaction ratios). Reforming of the flattened areas of the cladding on those rods was attempted to make the rod cross sections more nearly circular; some of the reformed rods passed through the funnel and into the canister.

  14. Electronegativity calculation of bulk modulus and band gap of ternary ZnO-based alloys

    SciTech Connect (OSTI)

    Li, Keyan; Kang, Congying [State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China)] [State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); Xue, Dongfeng, E-mail: dongfeng@ciac.jl.cn [State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China) [State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2012-10-15

    In this work, the bulk moduli and band gaps of M{sub x}Zn{sub 1?x}O (M = Be, Mg, Ca, Cd) alloys in the whole composition range were quantitatively calculated by using the electronegativity-related models for bulk modulus and band gap, respectively. We found that the change trends of bulk modulus and band gap with an increase of M concentration x are same for Be{sub x}Zn{sub 1?x}O and Cd{sub x}Zn{sub 1?x}O, while the change trends are reverse for Mg{sub x}Zn{sub 1?x}O and Ca{sub x}Zn{sub 1?x}O. It was revealed that the bulk modulus is related to the valence electron density of atoms whereas the band gap is strongly influenced by the detailed chemical bonding behaviors of constituent atoms. The current work provides us a useful guide to compositionally design advanced alloy materials with both good mechanical and optoelectronic properties.

  15. Heterojunctions of model CdTe/CdSe mixtures

    SciTech Connect (OSTI)

    van Swol, Frank; Zhou, Xiaowang W.; Challa, Sivakumar R.; Martin, James E.

    2015-03-18

    We report on the strain behavior of compound mixtures of model group IIVI semiconductors. We use the StillingerWeber Hamiltonian that we recently introduced, specifically developed to model binary mixtures of group IIVI compounds such as CdTe and CdSe. We also employ molecular dynamics simulations to examine the behavior of thin sheets of material, bilayers of CdTe and CdSe. The lattice mismatch between the two compounds leads to a strong bending of the entire sheet, with about a 0.5 to 1 deflection between neighboring planes. To further analyze bilayer bending, we introduce a simple one-dimensional model and use energy minimization to find the angle of deflection. The analysis is equivalent to a least-squares straight line fit. We consider the effects of bilayers which are asymmetric with respect to the thickness of the CdTe and CdSe parts. We thus learn that the bending can be subdivided into four kinds depending on the compressive/tensile nature of each outer plane of the sheet. We use this approach to directly compare our findings with experimental results on the bending of CdTe/CdSe rods. To reduce the effects of the lattice mismatch we explore diffuse interfaces, where we mix (i.e. alloy) Te and Se, and estimate the strain response.

  16. Heterojunctions of model CdTe/CdSe mixtures

    SciTech Connect (OSTI)

    van Swol, Frank; Zhou, Xiaowang W.; Challa, Sivakumar R.; Martin, James E.

    2015-03-18

    We report on the strain behavior of compound mixtures of model group II-VI semiconductors. We use the Stillinger-Weber Hamiltonian that we recently introduced, specifically developed to model binary mixtures of group II-VI compounds such as CdTe and CdSe. We also employ molecular dynamics simulations to examine the behavior of thin sheets of material, bilayers of CdTe and CdSe. The lattice mismatch between the two compounds leads to a strong bending of the entire sheet, with about a 0.5 to 1° deflection between neighboring planes. To further analyze bilayer bending, we introduce a simple one-dimensional model and use energy minimization to find the angle of deflection. The analysis is equivalent to a least-squares straight line fit. We consider the effects of bilayers which are asymmetric with respect to the thickness of the CdTe and CdSe parts. We thus learn that the bending can be subdivided into four kinds depending on the compressive/tensile nature of each outer plane of the sheet. We use this approach to directly compare our findings with experimental results on the bending of CdTe/CdSe rods. To reduce the effects of the lattice mismatch we explore diffuse interfaces, where we mix (i.e. alloy) Te and Se, and estimate the strain response.

  17. Heterojunctions of model CdTe/CdSe mixtures

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    van Swol, Frank; Zhou, Xiaowang W.; Challa, Sivakumar R.; Martin, James E.

    2015-03-18

    We report on the strain behavior of compound mixtures of model group II-VI semiconductors. We use the Stillinger-Weber Hamiltonian that we recently introduced, specifically developed to model binary mixtures of group II-VI compounds such as CdTe and CdSe. We also employ molecular dynamics simulations to examine the behavior of thin sheets of material, bilayers of CdTe and CdSe. The lattice mismatch between the two compounds leads to a strong bending of the entire sheet, with about a 0.5 to 1° deflection between neighboring planes. To further analyze bilayer bending, we introduce a simple one-dimensional model and use energy minimization tomore » find the angle of deflection. The analysis is equivalent to a least-squares straight line fit. We consider the effects of bilayers which are asymmetric with respect to the thickness of the CdTe and CdSe parts. We thus learn that the bending can be subdivided into four kinds depending on the compressive/tensile nature of each outer plane of the sheet. We use this approach to directly compare our findings with experimental results on the bending of CdTe/CdSe rods. To reduce the effects of the lattice mismatch we explore diffuse interfaces, where we mix (i.e. alloy) Te and Se, and estimate the strain response.« less

  18. Blue and green electroluminescence from CdSe nanocrystal quantum-dot-quantum-wells

    SciTech Connect (OSTI)

    Lu, Y. F.; Cao, X. A.

    2014-11-17

    CdS/CdSe/ZnS quantum dot quantum well (QDQW) nanocrystals were synthesized using the successive ion layer adsorption and reaction technique, and their optical properties were tuned by bandgap and strain engineering. 3-monolayer (ML) CdSe QWs emitted blue photoluminescence at 467?nm with a spectral full-width-at-half-maximum of ?30?nm. With a 3 ML ZnS cladding layer, which also acts as a passivating and strain-compensating layer, the QDQWs acquired a ?35% quantum yield of the QW emission. Blue and green electroluminescence (EL) was obtained from QDQW light-emitting devices with 34.5 ML CdSe QWs. It was found that as the peak blueshifted, the overall EL was increasingly dominated by defect state emission due to poor hole injection into the QDQWs. The weak EL was also attributed to strong field-induced charge separation resulting from the unique QDQW geometry, weakening the oscillator strength of optical transitions.

  19. High-efficiency, flexible CdTe solar cells on ultra-thin glass substrates

    SciTech Connect (OSTI)

    Mahabaduge, H. P.; Rance, W. L.; Burst, J. M.; Reese, M. O.; Gessert, T. A.; Metzger, W. K.; Barnes, T. M.; Meysing, D. M.; Wolden, C. A.; Li, J.; Beach, J. D.; Garner, S.

    2015-03-30

    Flexible, high-efficiency, low-cost solar cells can enable applications that take advantage of high specific power, flexible form factors, lower installation and transportation costs. Here, we report a certified record efficiency of 16.4% for a flexible CdTe solar cell that is a marked improvement over the previous standard (14.05%). The improvement was achieved by replacing chemical-bath-deposited CdS with sputtered CdS:O and also replacing the high-temperature sputtered ZnTe:Cu back contact layer with co-evaporated and rapidly annealed ZnTe:Cu. We use quantum efficiency and capacitance-voltage measurements combined with device simulations to identify the reasons for the increase in efficiency. Both device simulations and experimental results show that higher carrier density can quantitatively account for the increased open circuit voltage (V{sub OC}) and Fill Factor (FF), and likewise, the increase in short circuit current density (J{sub SC}) can be attributed to the more transparent CdS:O.

  20. Enhancement of photoluminescence in ZnS/ZnO quantum dots interfacial heterostructures

    SciTech Connect (OSTI)

    Rajalakshmi, M.; Sohila, S.; Ramesh, R.; Bhalerao, G.M.

    2012-09-15

    Highlights: ? ZnS/ZnO quantum dots (QDs) were synthesized by controlled oxidation of ZnS nanoparticles. ? Interfacial heterostructure formation of ZnS/ZnO QDs is seen in HRTEM. ? Enormous enhancement of UV emission (?10 times) in ZnS/ZnO QDs heterostructure is observed. ? Phonon confinement effect is seen in the Raman spectrum. -- Abstract: ZnS/ZnO quantum dots (QDs) were synthesized by controlled oxidation of ZnS nanoparticles. HRTEM image showed small nanocrystals of size 4 nm and the magnified image of single quantum dot shows interfacial heterostructure formation. The optical absorption spectrum shows a blue shift of 0.19 and 0.23 eV for ZnO and ZnS QDs, respectively. This is due to the confinement of charge carries within the nanostructures. Enormous enhancement in UV emission (10 times) is reported which is attributed to interfacial heterostructure formation. Raman spectrum shows phonons of wurtzite ZnS and ZnO. Phonon confinement effect is seen in the Raman spectrum wherein LO phonon peaks of ZnS and ZnO are shifted towards lower wavenumber side and are broadened.

  1. Simulation of Electric Field in Semi Insulating Au/CdTe/Au Detector under Flux

    SciTech Connect (OSTI)

    Franc, J.; James, R.; Grill, R.; Kubat, J.; Belas, E.; Hoschl, P.; Moravec, P.; Praus, P.

    2009-08-02

    We report our simulations on the profile of the electric field in semi insulating CdTe and CdZnTe with Au contacts under radiation flux. The type of the space charge and electric field distribution in the Au/CdTe/Au structure is at high fluxes result of a combined influence of charge formed due to band bending at the electrodes and from photo generated carriers, which are trapped at deep levels. Simultaneous solution of drift-diffusion and Poisson equations is used for the calculation. We show, that the space charge originating from trapped photo-carriers starts to dominate at fluxes 10{sup 15}-10{sup 16}cm{sup -2}s{sup -1}, when the influence of contacts starts to be negligible.

  2. Post-Growth Annealing of Bridgman-grown CdZnTe and CdMnTe Crystals...

    Office of Scientific and Technical Information (OSTI)

    ... Section A, Accelerators, Spectrometers, Detectors and Associated Equipment Additional Journal Information: Journal Volume: 784; Journal ID: ISSN 0168-9002 Publisher: Elsevier ...

  3. High efficiency thin film CdTe and a-Si based solar cells

    SciTech Connect (OSTI)

    Compaan, A. D.; Deng, X.; Bohn, R. G.

    2000-01-04

    This report describes work done by the University of Toledo during the first year of this subcontract. During this time, the CdTe group constructed a second dual magnetron sputter deposition facility; optimized reactive sputtering for ZnTe:N films to achieve 10 ohm-cm resistivity and {approximately}9% efficiency cells with a copper-free ZnTe:N/Ni contact; identified Cu-related photoluminescence features and studied their correlation with cell performance including their dependence on temperature and E-fields; studied band-tail absorption in CdS{sub x}Te{sub 1{minus}x} films at 10 K and 300 K; collaborated with the National CdTe PV Team on (1) studies of high-resistivity tin oxide (HRT) layers from ITN Energy Systems, (2) fabrication of cells on the HRT layers with 0, 300, and 800-nm CdS, and (3) preparation of ZnTe:N-based contacts on First Solar materials for stress testing; and collaborated with Brooklyn College for ellipsometry studies of CdS{sub x}Te{sub 1{minus}x} alloy films, and with the University of Buffalo/Brookhaven NSLS for synchrotron X-ray fluorescence studies of interdiffusion in CdS/CdTe bilayers. The a-Si group established a baseline for fabricating a-Si-based solar cells with single, tandem, and triple-junction structures; fabricated a-Si/a-SiGe/a-SiGe triple-junction solar cells with an initial efficiency of 9.7% during the second quarter, and 10.6% during the fourth quarter (after 1166 hours of light-soaking under 1-sun light intensity at 50 C, the 10.6% solar cells stabilized at about 9%); fabricated wide-bandgap a-Si top cells, the highest Voc achieved for the single-junction top cell was 1.02 V, and top cells with high FF (up to 74%) were fabricated routinely; fabricated high-quality narrow-bandgap a-SiGe solar cells with 8.3% efficiency; found that bandgap-graded buffer layers improve the performance (Voc and FF) of the narrow-bandgap a-SiGe bottom cells; and found that a small amount of oxygen partial pressure ({approximately}2 {times} 10{sup {minus}5} torr) was beneficial for growing high-quality films from ITO targets.

  4. Thermodynamic properties of model CdTe/CdSe mixtures

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    van Swol, Frank; Zhou, Xiaowang W.; Challa, Sivakumar R.; Martin, James E.

    2015-02-20

    We report on the thermodynamic properties of binary compound mixtures of model groups II–VI semiconductors. We use the recently introduced Stillinger–Weber Hamiltonian to model binary mixtures of CdTe and CdSe. We use molecular dynamics simulations to calculate the volume and enthalpy of mixing as a function of mole fraction. The lattice parameter of the mixture closely follows Vegard's law: a linear relation. This implies that the excess volume is a cubic function of mole fraction. A connection is made with hard sphere models of mixed fcc and zincblende structures. We found that the potential energy exhibits a positive deviation frommore » ideal soluton behaviour; the excess enthalpy is nearly independent of temperatures studied (300 and 533 K) and is well described by a simple cubic function of the mole fraction. Using a regular solution approach (combining non-ideal behaviour for the enthalpy with ideal solution behaviour for the entropy of mixing), we arrive at the Gibbs free energy of the mixture. The Gibbs free energy results indicate that the CdTe and CdSe mixtures exhibit phase separation. The upper consolute temperature is found to be 335 K. Finally, we provide the surface energy as a function of composition. Moreover, it roughly follows ideal solution theory, but with a negative deviation (negative excess surface energy). This indicates that alloying increases the stability, even for nano-particles.« less

  5. Structural and optical properties of ZnO and ZnO:Fe nanoparticles under

    Office of Scientific and Technical Information (OSTI)

    dense electronic excitations (Journal Article) | SciTech Connect Structural and optical properties of ZnO and ZnO:Fe nanoparticles under dense electronic excitations Citation Details In-Document Search Title: Structural and optical properties of ZnO and ZnO:Fe nanoparticles under dense electronic excitations We report on the changes in structural, morphological, and optical properties of sol-gel derived ZnO and ZnO:Fe nanoparticles due to dense electronic excitations produced by heavy ion

  6. High Compositional Homogeneity of CdTexSe1-x Crystals Grown by the Bridgman Method

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Roy, U. N.; Bolotnikov, A. E.; Camarda, G. S.; Cui, Y.; Hossain, A.; Lee, K.; Lee, W.; Tappero, R.; Yang, G.; Gul, R.; et al

    2015-02-03

    We obtained high-quality CdTexSe1-x (CdTeSe) crystals from ingots grown by the vertical Bridgman technique. The compositional uniformity of the ingots was evaluated by X-ray fluorescence at BNL’s National Synchrotron Light Source X27A beam line. The resulting compositional homogeneity was highly uniform throughout the ingot, and the effective segregation coefficient of Se was ~1.0. This uniformity offers potential opportunity to enhance the yield of the materials for both infrared substrate and radiation-detector applications, so greatly lowering the cost of production and also offering us the prospect to grow large-diameter ingots for use as large-area substrates and for producing higher efficiency gamma-raymore » detectors. The concentration of secondary phases was found to be much lower, by eight- to ten fold compared to that of conventional CdxZn1-xTe (CdZnTe or CZT).« less

  7. CD DVD Retrieval | netl.doe.gov

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    CD DVD Retrieval Publications KMD Contacts Project Summaries EPAct 2005 Arctic Energy Office Announcements Software Stripper Wells The user can download the complete CD/DVD via zip files, or if applicable use the interactive webpages to review the content online. Users can also request mailed copies of the media using the NETL CD-DVD ordering system. CD Image Title: Naturally Fracture Reservoir Simulator: FRACGEN & NFFLOW Info: The DOE sponsored a project to simulate the behavior of tight,

  8. Photodeposition of Pt on Colloidal CdS and CdSe/CdS Semiconductor Nanostructures

    SciTech Connect (OSTI)

    Dukovic, Gordana; Merkle, Maxwell G.; Nelson, James H.; Hughes, Steven M.; Alivisatos, A. Paul

    2008-08-06

    Semiconductor photocatalysis has been identified as a promising avenue for the conversion of solar energy into environmentally friendly fuels, most notably by the production of hydrogen from water.[1-5] Nanometer-scale materials in particular have attracted considerable scientific attention as the building blocks for light-harvesting applications.[6,7] Their desirable attributes include tunability of the optical properties with size, amenability to relatively inexpensive low-temperature processing, and a high degree of synthetic sophistication leading to increasingly complex and multi-functional architectures. For photocatalysis in particular, the high surface-to-volume ratios in nanoscale materials should lead to an increased availability of carriers for redox reactions on the nanoparticle surface. Recombination of photoexcited carriers directly competes with photocatalytic activity.[3] Charge separation is often achieved with multi-component heterostructures. An early example is the case of TiO2 powders functionalized with Pt and RuO2 particles, where photoexcited electrons are transferred to Pt (the reduction site) and holes to RuO2 (the oxidation site).[8] More recently, many colloidally synthesized nanometer-scale metal-semiconductor heterostructures have been reported.[7,9,10] A majority of these structures are made by thermal methods.[7,10] We have chosen to study photochemical formation of metal-semiconductor heterostructures. The detailed understanding of the mechanisms involved in photodeposition of metals on nanometer-scale semiconductors is necessary to enable a high degree of synthetic control. At the same time, because the results of metal deposition can be directly observed by electron microscopy, it can be used to understand how factors such as nanocrystal composition, shape, carrier dynamics, and surface chemistry influence the photochemical properties of semiconductor nanocrystals. In this communication, we report on the photodeposition of Pt on colloidal CdS and CdSe/CdS core/shell nanocrystals. Among the II-VI semiconductors, CdS is of particular interest because it has the correct band alignment for water photolysis[2] and has been demonstrated to be photocatalytically active.[11-16] We have found that the photoexcitation of CdS and CdSe/CdS in the presence of an organometallic Pt precursor leads to deposition of Pt nanoparticles on the semiconductor surface. Stark differences are observed in the Pt nanoparticle location on the two substrates, and the photodeposition can be completely inhibited by the modification of the semiconductor surface. Our results suggest that tuning of the semiconductor band structure, spatial organization and surface chemistry should be crucial in the design of photocatalytic nanostructures.

  9. Ultraviolet emission from a multi-layer graphene/MgZnO/ZnO light-emitting diode

    SciTech Connect (OSTI)

    Kang, Jang-Won; Choi, Yong-Seok; Goo Kang, Chang; Hun Lee, Byoung [School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Kim, Byeong-Hyeok [Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Tu, C. W. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093-0407 (United States); Park, Seong-Ju, E-mail: sjpark@gist.ac.kr [School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)

    2014-02-03

    We report on ultraviolet emission from a multi-layer graphene (MLG)/MgZnO/ZnO light-emitting diodes (LED). The p-type MLG and MgZnO in the MLG/MgZnO/ZnO LED are used as transparent hole injection and electron blocking layers, respectively. The current-voltage characteristics of the MLG/MgZnO/ZnO LED show that current transport is dominated by tunneling processes in the MgZnO barrier layer under forward bias conditions. The holes injected from p-type MLG recombine efficiently with the electrons accumulated in ZnO, and the MLG/MgZnO/ZnO LED shows strong ultraviolet emission from the band edge of ZnO and weak red-orange emission from the deep levels of ZnO.

  10. Cytotoxicity of InP/ZnS quantum dots related to reactive oxygen species generation.

    SciTech Connect (OSTI)

    Chibli, H.; Carlini, L.; Park, S.; Dimitrijevic, N. M.; Nadeau, J. L.

    2011-01-01

    Indium phosphide (InP) quantum dots (QDs) have emerged as a presumably less hazardous alternative to cadmium-based particles, but their cytotoxicity has not been well examined. Although their constituent elements are of very low toxicity to cells in culture, they nonetheless exhibit phototoxicity related to generation of reactive oxygen species by excited electrons and/or holes interacting with water and molecular oxygen. Using spin-trap electron paramagnetic resonance (EPR) spectroscopy and reporter assays, we find a considerable amount of superoxide and a small amount of hydroxyl radical formed under visible illumination of biocompatible InP QDs with a single ZnS shell, comparable to what is seen with CdTe. A double thickness shell reduces the reactive oxygen species concentration approximately two-fold. Survival assays in five cell lines correspondingly indicate a distinct reduction in toxicity with the double-shell InP QDs. Toxicity varies significantly across cell lines according to the efficiency of uptake, being overall significantly less than what is seen with CdTe or CdSe/ZnS. This indicates that InP QDs are a useful alternative to cadmium-containing QDs, while remaining capable of electron-transfer processes that may be undesirable or which may be exploited for photosensitization applications.

  11. ZnS/Zn(O,OH)S-based buffer layer deposition for solar cells

    DOE Patents [OSTI]

    Bhattacharya, Raghu N.

    2009-11-03

    The invention provides CBD ZnS/Zn(O,OH)S and spray deposited ZnS/Zn(O,OH)S buffer layers prepared from a solution of zinc salt, thiourea and ammonium hydroxide dissolved in a non-aqueous/aqueous solvent mixture or in 100% non-aqueous solvent. Non-aqueous solvents useful in the invention include methanol, isopropanol and triethyl-amine. One-step deposition procedures are described for CIS, CIGS and other solar cell devices.

  12. CD

    Annual Energy Outlook [U.S. Energy Information Administration (EIA)]

    Square Footage, and Number of Workers in the Building.) Metal Panel: A wall construction panel made of aluminum or galvanized steel fabricated in factories and fastened to the...

  13. Materials Data on ZnCdPt2 (SG:123) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2015-02-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  14. Simulation, Modeling, and Crystal Growth of Cd0.9Zn0.1Te for...

    Office of Scientific and Technical Information (OSTI)

    High-quality, large (10 cm long and 2.5 cm diameter), nuclear spectrometer grade Cdsub ... 241Am and sup 137Cs clearly detected 59.6 and 662 keV energies with energy resolution ...

  15. Effects of chemo-mechanical polishing on CdZnTe X-ray and gamma...

    Office of Scientific and Technical Information (OSTI)

    Authors: Egarievwe, Stephen E. 1 ; Hossain, Anwar 2 ; Okwechime, Ifechukwude O. 3 ; Gul, Rubi 1 ; James, Ralph B. 2 + Show Author Affiliations Alabama A&M Univ., Normal, ...

  16. sup 3 P Hg, Cd, and Zn photosensitized chemistry of vinyl halides in krypton matrix

    SciTech Connect (OSTI)

    Cartland, H.E.; Pimentel, G.C. )

    1990-01-25

    The reaction of group IIB metals in the {sup 3}P state with vinyl fluoride, chloride, and bromide is studied in krypton matrix. The primary process in all cases is hydrogen halide elimination to form a hydrogen halide/acetylene hydrogen-bonded complex. Insertion of metal atoms into C-Cl and C-Br bonds, but not into C-H and C-F bonds, is also observed. The insertion photochemistry can be explained by a mechanism which requires that the process occur on a triplet surface with the vinyl halide in the planar ground-state conformation.

  17. Near-Unity Quantum Yields of Biexciton Emission from CdSe=CdS Nanocrystals

    Office of Scientific and Technical Information (OSTI)

    Measured Using Single-Particle Spectroscopy (Journal Article) | SciTech Connect Near-Unity Quantum Yields of Biexciton Emission from CdSe=CdS Nanocrystals Measured Using Single-Particle Spectroscopy Citation Details In-Document Search Title: Near-Unity Quantum Yields of Biexciton Emission from CdSe=CdS Nanocrystals Measured Using Single-Particle Spectroscopy Biexciton photoluminescence (PL) quantum yields (Q2X) of individual CdSe/CdS core-shell nanocrystal quantum dots with various shell

  18. Synthesis, crystal structures, and physical properties of the new Zintl phases A{sub 21}Zn{sub 4}Pn{sub 18} (A=Ca, Eu; Pn=As, Sb)—Versatile arrangements of [ZnPn{sub 4}] tetrahedra

    SciTech Connect (OSTI)

    Suen, Nian-Tzu; Wang, Yi; Bobev, Svilen

    2015-07-15

    Four new Zintl phases, Ca{sub 21}Zn{sub 4}As{sub 18}, Ca{sub 21}Zn{sub 4}Sb{sub 18}, Eu{sub 21}Zn{sub 4}As{sub 18} and Eu{sub 21}Zn{sub 4}Sb{sub 18} have been synthesized by metal flux reactions. Their structures have been established from single-crystal X-ray diffraction. Despite the similar chemical makeup and the identical formulae, the structures of the four compounds are not the same—Ca{sub 21}Zn{sub 4}As{sub 18}, Ca{sub 21}Zn{sub 4}Sb{sub 18} and Eu{sub 21}Zn{sub 4}As{sub 18} crystallize in the monoclinic space group C2/m (No. 12, Z=4) with the β-Ca{sub 21}Mn{sub 4}Sb{sub 18} structure type, while Eu{sub 21}Zn{sub 4}Sb{sub 18} adopts the Ba{sub 21}Cd{sub 4}Sb{sub 18} structure type with the orthorhombic space group Cmce (No. 64, Z=8). Both structures are based on ZnAs{sub 4} or ZnSb{sub 4} tetrahedra, linked in slightly different ways, and Ca{sup 2+} and Eu{sup 2+} cations that fill the space between them. The structural relationships between the title compounds and other known ternary phases with intricate structures are discussed. Electrical resistivity measurement on single-crystalline Eu{sub 21}Zn{sub 4}Sb{sub 18} suggests an intrinsic semiconductor behavior with a band gap of ca. 0.2 eV. The temperature dependent DC magnetization measurement on the same material indicates Curie–Weiss paramagnetism in the high-temperature regime, and a spontaneous antiferromagnetic ordering below 8 K. The calculated effective moments of Eu confirm the divalent Eu{sup 2+} ground state, as expected from the Zintl–Klemm concept. - Graphical abstract: The four new Zintl phases—Ca{sub 21}Zn{sub 4}As{sub 18}, Ca{sub 21}Zn{sub 4}Sb{sub 18}, Eu{sub 21}Zn{sub 4}As{sub 18}, and Eu{sub 21}Zn{sub 4}Sb{sub 18}—crystallize in two structure types, showing the versatility in the arrangements of ZnAs{sub 4} and ZnSb{sub 4} tetrahedra. - Highlights: • Ca{sub 21}Zn{sub 4}As{sub 18}, Ca{sub 21}Zn{sub 4}Sb{sub 18}, Eu{sub 21}Zn{sub 4}As{sub 18}, and Eu{sub 21}Zn{sub 4}Sb{sub 18} are new compounds in the respective ternary phase diagrams. • They form with structure types, showing the versatility in the arrangements of ZnAs{sub 4} and ZnSb{sub 4} tetrahedra. • For both structures, the valence electron count follows the Zintl–Klemm rules.

  19. Recycling of CdTe photovoltaic waste

    DOE Patents [OSTI]

    Goozner, Robert E.; Long, Mark O.; Drinkard, Jr., William F.

    1999-01-01

    A method for extracting and reclaiming metals from scrap CdTe photovoltaic cells and manufacturing waste by leaching the waste with a leaching solution comprising nitric acid and water, skimming any plastic material from the top of the leaching solution, separating the glass substrate from the liquid leachate and electrolyzing the leachate to separate Cd from Te, wherein the Te is deposits onto a cathode while the Cd remains in solution.

  20. WPN 10-3: Procurement Toolkit CD

    Broader source: Energy.gov [DOE]

    To issue the Procurement Toolkit CD to all Grantees, to share with their local agencies, for use in the Weatherization Assistance Program.

  1. Super-Poissonian Statistics of Photon Emission from Single CdSe-CdS

    Office of Scientific and Technical Information (OSTI)

    Core-Shell Nanocrystals Coupled to Metal Nanostructures (Journal Article) | SciTech Connect Super-Poissonian Statistics of Photon Emission from Single CdSe-CdS Core-Shell Nanocrystals Coupled to Metal Nanostructures Citation Details In-Document Search Title: Super-Poissonian Statistics of Photon Emission from Single CdSe-CdS Core-Shell Nanocrystals Coupled to Metal Nanostructures Authors: Park, Young-Shin ; Ghosh, Yagnaseni ; Chen, Yongfen ; Piryatinski, Andrei ; Xu, Ping ; Mack, Nathan H. ;

  2. CD-0, Approve Mission Need

    Broader source: Energy.gov [DOE]

    The Initiation Phase begins with the identification of a mission-related need. A Program Office will identify a credible performance gap between its current capabilities and capacities and those required to achieve the goals articulated in its strategic plan. The Mission Need Statement (MNS) is the translation of this gap into functional requirements that cannot be met through other than material means. It should describe the general parameters of the solution and why it is critical to the overall accomplishment of the Department’s mission, including the benefits to be realized. The mission need is independent of a particular solution, and should not be defined by equipment, facility, technological solution, or physical end-item. This approach allows the Program Office the flexibility to explore a variety of solutions and not limit potential solutions (refer to DOE G 413.3-17). The requirements needed to attain CD-0 are listed below.

  3. An electrostatic nanogenerator based on ZnO/ZnS core/shell electrets with stabilized quasi-permanent charge

    SciTech Connect (OSTI)

    Wang, Chao; Cai, Liang; Feng, Yajuan; Chen, Lin; Yan, Wensheng E-mail: zhsun@ustc.edu.cn; Liu, Qinghua; Yao, Tao; Hu, Fengchun; Pan, Zhiyun; Sun, Zhihu E-mail: zhsun@ustc.edu.cn; Wei, Shiqiang

    2014-06-16

    ZnO-based nanogenerators with excellent performance and convenient functionalization are particularly desirable for self-powered technology, which is however difficult to achieve simultaneously in traditional piezoelectric ZnO nanogenerators. Here, we report a design of electrostatic ZnO nanogenerator by virtue of a type-II ZnO/ZnS core/shell nanostructure electrets, which can turn acoustic waves into electric power with an energy conversion efficiency of 2.2%. The ZnO/ZnS core/shell electrets are charged by ultraviolet irradiation with a long-term stability of the electrostatic charges under ambient condition. The electronic and atomic structure evolution in the charged ZnO/ZnS core/shell electrets are also discussed by detailed experimental and theoretical investigations. This design opens up an alternative path for fabricating robust ZnO-based nanogenerator for future nanotechnology application.

  4. CdO-CdS nano-composites as improved photo-catalysts for the generation of hydrogen from water

    SciTech Connect (OSTI)

    Kahane, Shital V.; Mahamuni, Shailaja; Sasikala, R.; Sudarsan, V.

    2014-04-24

    CdO-CdS nanocomposites were prepared by polyol method followed by heating at 300C. XRD study confirmed the atomic scale mixing of CdO and CdS nanoparticles, leading to the formation of CdSO{sub 3} phase at the interfacial region between CdO and CdS. The enhancement in photo-catalytic activity for hydrogen generation from water is observed in case of CdO-CdS nanocomposites compared to individual CdS and CdO nanoparticles. Based on XRD, steady state and time resolved luminescence studies and surface area measurements, it is determined that, the fine mixing of CdS and CdO, higher surface area of the composite sample and increase in lifetime of the charge carriers are responsible for the observed increase in hydrogen yield from water when composite sample was used as the photo-catalyst compared to individual components.

  5. D= DOE/RG-0067

    Energy Savers [EERE]

    ... Effects of d i rect el e c t r i c f i elds , n o i s e , sex and age on maz e learn ing ... n i neteen Mas s achusetts towns i n M i dd l esex , E s sex , and Worc ester Count i es . ...

  6. The impact of oxygen incorporation during intrinsic ZnO sputtering on the performance of Cu(In,Ga)Se{sub 2} thin film solar cells

    SciTech Connect (OSTI)

    Lee, Kkotnim; Ok, Eun-A; Park, Jong-Keuk; Kim, Won Mok; Baik, Young-Joon; Jeong, Jeung-hyun; Kim, Donghwan

    2014-08-25

    We investigated the impact of incorporating 2% oxygen during intrinsic ZnO sputtering on the efficiency of Cu(In,Ga)Se{sub 2} solar cells. The added oxygen not only reduced the optical absorption loss of the Al-doped ZnO overlaying layer but also improved the electronic properties of the underlying CdS/Cu(In,Ga)Se{sub 2} by increasing carrier density, lowering defect level, and increasing diffusion length, eventually enhancing J{sub SC}, V{sub OC}, and fill factor. It was found that the Na doping concentration was significantly increased around the CdS/Cu(In,Ga)Se{sub 2} junction due to the plasma-activated oxygen. The improved electronic properties are better explained by the increased Na concentration than simply the oxygen-related defect passivation.

  7. Unique Challenges Accompany Thick-Shell CdSe/nCdS (n > 10) Nanocrystal Synthesis

    SciTech Connect (OSTI)

    Guo, Y; Marchuk, K; Abraham, R; Sampat, S; Abraham, R.; Fang, N; Malko, AV; Vela, J

    2011-12-23

    Thick-shell CdSe/nCdS (n {ge} 10) nanocrystals were recently reported that show remarkably suppressed fluorescence intermittency or 'blinking' at the single-particle level as well as slow rates of Auger decay. Unfortunately, whereas CdSe/nCdS nanocrystal synthesis is well-developed up to n {le} 6 CdS monolayers (MLs), reproducible syntheses for n {ge} 10 MLs are less understood. Known procedures sometimes result in homogeneous CdS nucleation instead of heterogeneous, epitaxial CdS nucleation on CdSe, leading to broad and multimodal particle size distributions. Critically, obtained core/shell sizes are often below those desired. This article describes synthetic conditions specific to thick-shell growth (n {ge} 10 and n {ge} 20 MLs) on both small (sub2 nm) and large (>4.5 nm) CdSe cores. We find added secondary amine and low concentration of CdSe cores and molecular precursors give desired core/shell sizes. Amine-induced, partial etching of CdSe cores results in apparent shell-thicknesses slightly beyond those desired, especially for very-thick shells (n {ge} 20 MLs). Thermal ripening and fast precursor injection lead to undesired homogeneous CdS nucleation and incomplete shell growth. Core/shells derived from small CdSe (1.9 nm) have longer PL lifetimes and more pronounced blinking at single-particle level compared with those derived from large CdSe (4.7 nm). We expect our new synthetic approach will lead to a larger throughput of these materials, increasing their availability for fundamental studies and applications.

  8. Critical Decision 2 (CD-2) Approval Template | Department of...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Critical Decision 2 (CD-2) Approval Template Critical Decision 2 (CD-2) Approval Template File ExampleCD-2Template02-14-12.docx More Documents & Publications Example BCP...

  9. CdTe devices and method of manufacturing same

    DOE Patents [OSTI]

    Gessert, Timothy A.; Noufi, Rommel; Dhere, Ramesh G.; Albin, David S.; Barnes, Teresa; Burst, James; Duenow, Joel N.; Reese, Matthew

    2015-09-29

    A method of producing polycrystalline CdTe materials and devices that incorporate the polycrystalline CdTe materials are provided. In particular, a method of producing polycrystalline p-doped CdTe thin films for use in CdTe solar cells in which the CdTe thin films possess enhanced acceptor densities and minority carrier lifetimes, resulting in enhanced efficiency of the solar cells containing the CdTe material are provided.

  10. ZnO and MgZnO Nanocrystalline Flexible Films: Optical and Material Properties

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Huso, Jesse; Morrison, John L.; Che, Hui; Sundararajan, Jency P.; Yeh, Wei Jiang; McIlroy, David; Williams, Thomas J.; Bergman, Leah

    2011-01-01

    An emore » merging material for flexible UV applications is Mg x Zn 1 − x O which is capable of tunable bandgap and luminescence in the UV range of ~3.4 eV–7.4 eV depending on the composition x . Studies on the optical and material characteristics of ZnO and Mg 0.3 Zn 0.7 O nanocrystalline flexible films are presented. The analysis indicates that the ZnO and Mg 0.3 Zn 0.7 O have bandgaps of 3.34 eV and 4.02 eV, respectively. The photoluminescence (PL) of the ZnO film was found to exhibit a structural defect-related emission at ~3.316 eV inherent to the nanocrystalline morphology. The PL of the Mg 0.3 Zn 0.7 O film exhibits two broad peaks at 3.38 eV and at 3.95 eV that are discussed in terms of the solubility limit of the ZnO-MgO alloy system. Additionally, external deformation of the film did not have a significant impact on its properties as indicated by the Raman LO-mode behavior, making these films attractive for UV flexible applications.« less

  11. Crystal structure and magnetic properties and Zn substitution effects on the spin-chain compound Sr{sub 3}Co{sub 2}O{sub 6}

    SciTech Connect (OSTI)

    Wang, Xia [Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba Ibaraki 305-0044 (Japan); Department of Chemistry, Graduate School of Science, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan); Guo, Yanfeng, E-mail: Yangfeng.Guo@physics.ox.ac.uk [Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba Ibaraki 305-0044 (Japan); Sun, Ying [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba Ibaraki 305-0044 (Japan); Tsujimoto, Yoshihiro [Materials Processing Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba Ibaraki 305-0047 (Japan); Matsushita, Yoshitaka [Materials Analysis Station, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba Ibaraki 305-0047 (Japan); Yamaura, Kazunari, E-mail: yamaura.kazunari@nims.go.jp [Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba Ibaraki 305-0044 (Japan); Department of Chemistry, Graduate School of Science, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan)

    2013-08-15

    The effects of substituting Co on the spin-chain compound Sr{sub 3}Co{sub 2}O{sub 6} with Zn were investigated by synchrotron X-ray diffraction, magnetic susceptibility, isothermal magnetization, and specific heat measurements. To the best of our knowledge, this is the first report to describe the successful substitution of Co in Sr{sub 3}Co{sub 2}O{sub 6} with Zn. The substitution was carried out by a method involving high pressures and temperatures to obtain Sr{sub 3}CoZnO{sub 6}, which crystalized into a K{sub 4}CdCl{sub 6}-derived rhombohedral structure with a space group of R-3c, similar to the host compound. With the Zn substitution, the Ising-type magnetic anisotropy of the host compound remarkably reduced; the newly formed Sr{sub 3}CoZnO{sub 6} became magnetically isotropic with Heisenberg-type characteristics. This could probably be ascribed to the establishment of a different interaction pathway, Co{sup 4+}(S=1/2)OZn{sup 2+}(S=0)OCo{sup 4+}(S=1/2). Details of the magnetic properties of Zn substituted Sr{sub 3}Co{sub 2}O{sub 6} were reported. - Graphical abstract: Crystal structure of the spin-chain compound Sr{sub 3}CoZnO{sub 6} synthesized at 6 GPa. Zn atoms preferably occupy the trigonal prism sites rather than the octahedral sites. As a result, the compound is much magnetically isotropic. Highlights: Effects of substituting Co with Zn on spin-chain magnetism of Sr{sub 3}Co{sub 2}O{sub 6} were studied. High-pressure synthesis resulted in a solid solution of Sr{sub 3}CoZnO{sub 6}. Sr{sub 3}CoZnO{sub 6} showed more isotropic magnetism than the host Sr{sub 3}Co{sub 2}O{sub 6}.

  12. Arrays of ZnO/CuIn{sub x}Ga{sub 1?x}Se{sub 2} nanocables with tunable shell composition for efficient photovoltaics

    SciTech Connect (OSTI)

    Akram, Muhammad Aftab; Javed, Sofia; Xu, Jun; Mujahid, Mohammad; Lee, Chun-Sing

    2015-05-28

    Arrays of one-dimensional (1D) nanostructure are receiving much attention for their optoelectronic and photovoltaic applications due to their advantages in light absorption, charge separation, and transportation. In this work, arrays of ZnO/CuIn{sub x}Ga{sub 1?x}Se{sub 2} core/shell nanocables with tunable shell compositions over the full range of 0???x???1 have been controllably synthesized. Chemical conversions of ZnO nanorods to a series of ZnO-based nanocables, including ZnO/ZnSe, ZnO/CuSe, ZnO/CuSe/In{sub x}Ga{sub 1?x}, ZnO/CuSe/(In{sub x}Ga{sub 1?x}){sub 2}Se{sub 3}, and ZnO/CuIn{sub x}Ga{sub 1?x}Se{sub 2}, are well designed and successfully achieved. Composition-dependent influences of the CuIn{sub x}Ga{sub 1?x}Se{sub 2} shells on photovoltaic performance are investigated. It is found that the increase in indium content (x) leads to an increase in short-circuit current density (J{sub SC}) but a decrease in open-circuit voltage (V{sub OC}) for the ZnO/CuIn{sub x}Ga{sub 1?x}Se{sub 2} nanocable solar cells. An array of ZnO/CuIn{sub 0.67}Ga{sub 0.33}Se{sub 2} nanocables with a length of ?1??m and a shell thickness of ?10?nm exhibits a bandgap of 1.20?eV, and yields a maximum power conversion efficiency of 1.74% under AM 1.5?G illumination at an intensity of 100 mW/cm{sup 2}. It dramatically surpasses that (0.22%) of the ZnO/CuIn{sub 0.67}Ga{sub 0.33}Se{sub 2} planar thin-film device. Our work reveals that 1D nanoarray allows efficient photovoltaics without using toxic CdS buffer layer.

  13. Recycling of CdTe photovoltaic waste

    DOE Patents [OSTI]

    Goozner, Robert E.; Long, Mark O.; Drinkard, Jr., William F.

    1999-04-27

    A method for extracting and reclaiming metals from scrap CdTe photovoltaic cells and manufacturing waste by leaching the metals in dilute nitric acid, leaching the waste with a leaching solution comprising nitric acid and water, skimming any plastic material from the top of the leaching solution, separating the glass substrate from the liquid leachate, adding a calcium containing base to the leachate to precipitate Cd and Te, separating the precipitated Cd and Te from the leachate, and recovering the calcium-containing base.

  14. Recycling of CdTe photovoltaic waste

    DOE Patents [OSTI]

    Goozner, R.E.; Long, M.O.; Drinkard, W.F. Jr.

    1999-04-27

    A method for extracting and reclaiming metals from scrap CdTe photovoltaic cells and manufacturing waste by leaching the metals in dilute nitric acid, leaching the waste with a leaching solution comprising nitric acid and water, skimming any plastic material from the top of the leaching solution, separating the glass substrate from the liquid leachate, adding a calcium containing base to the leachate to precipitate Cd and Te, separating the precipitated Cd and Te from the leachate, and recovering the calcium-containing base. 3 figs.

  15. Homoepitaxy of ZnO and MgZnO Films at 90 C

    SciTech Connect (OSTI)

    Ehrentraut, Dirk; Goh, Gregory K.L.; Fujii, Katsushi; Ooi, Chin Chun; Quang, Le Hong; Fukuda, Tsuguo; Kano, Masataka; Zhang, Yuantao; Matsuoka, Takashi

    2014-06-01

    The aqueous synthesis of uniform single crystalline homoepitaxial zinc oxide, ZnO, and magnesium zinc oxide, Mg{sub x}Zn{sub 1?x}O, films under very low temperature conditions at T=90 C and ambient pressure has been explored. A maximum Mg content of 1 mol% was recorded by energy dispersive spectroscopy. The growth on the polar (0 0 0 1) and (0 0 0 1) faces resulted in films that are strongly different in their structural and optical quality as evidenced by high-resolution X-ray diffraction, secondary electron microscopy, and photoluminescence. This is a result of the chemistry and temperature of the solution dictating the stability range of growth-governing metastable species. The use of trisodium citrate, Na{sub 3}C{sub 6}H{sub 5}O{sub 7}, yielded coalesced, mirror-like homoepitaxial films whereas adding magnesium nitrate hexahydrate, Mg(NO{sub 3}){sub 2}6H{sub 2}O, favors the growth of films with pronounced faceting. - Graphical abstract: Homoepitaxial ZnO films grown from aqueous solution below boiling point of water on a ZnO substrate with off-orientation reveal parallel grooves that are characterized by (1 0 1{sup } 1) facets. Adding trisodium citrate yields closed, single-crystalline ZnO films, which can further be functionalized. Alloying with MgO yields MgZnO films with low Mg content only. - Highlights: A simple method to synthesize uniform single crystalline homoepitaxial ZnO and MgZnO films. ZnO growth on (0 0 0 1) and (0 0 0 1{sup }) face resulted in films that are strongly different in their structural and optical quality. Single crystalline MgZnO film was fabricated under mild conditions (90 C and ambient pressure). Mg incorporation of nearly 1 mol% was obtained while maintaining single phase wurtzite structure.

  16. Junction Evolution During Fabrication of CdS/CdTe Thin-film PV Solar Cells (Presentation)

    SciTech Connect (OSTI)

    Gessert, T. A.

    2010-09-01

    Discussion of the formation of CdTe thin-film PV junctions and optimization of CdTe thin-film PV solar cells.

  17. Energy efficiency CD ROM. Final technical report

    SciTech Connect (OSTI)

    Totten, Michael

    1998-01-01

    The Center for Renewable Energy and SustainableTechnology (CREST) has completed the three tasks of subcontract DE-FC36-97GO10228. Three separate multimedia CD-ROM products were developed.

  18. Director's CD-1/Trial CD-2 Review of the MINERvA Project

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    1/Trial CD-2 Review of the MINERvA Project Main INjector ExpeRiment v-A December 13-15, 2005 | Overview | General Reference Material | CD-1/CD-2 Documentation| Link to the Directorate Web Page for this review Review Overview Information Charge to the Committee (pdf) Agenda (pdf - linked to talks) List of Prepared Breakout Talks (pdf) Review Committee (pdf) Video and Phone Connection Numbers (doc) Information for Visitors Bringing Laptops to Fermilab (doc) Final Report - Director's Prelimianary

  19. Indexing and TEM Sample Preparation of Isolated CdTe/CdS Nano-Islands.

    Office of Scientific and Technical Information (OSTI)

    (Conference) | SciTech Connect Conference: Indexing and TEM Sample Preparation of Isolated CdTe/CdS Nano-Islands. Citation Details In-Document Search Title: Indexing and TEM Sample Preparation of Isolated CdTe/CdS Nano-Islands. Abstract not provided. Authors: Aguirre, Brandon Adrian ; Cruz-Campa, Jose Luis ; Jungjohann, Katherine Leigh ; Pete, Douglas V. ; Zubia, David Publication Date: 2014-03-01 OSTI Identifier: 1140918 Report Number(s): SAND2014-2312C 505756 DOE Contract Number:

  20. Single crystalline multi-petal Cd nanoleaves prepared by thermal reduction of CdO

    SciTech Connect (OSTI)

    Khan, Waheed S.; National Institute for Biotechnology and Genetic Engineering , P.O. Box No. 577, Jhang Road, Faisalabad ; Cao, Chuanbao; Aslam, Imran; Ali, Zulfiqar; Butt, Faheem K.; Mahmood, Tariq; Nabi, Ghulam; Ihsan, Ayesha; Usman, Zahid; Rehman, Asma

    2013-02-15

    Highlights: ? Cd nanoleaves are obtained on abraded Cu substrate by thermal reduction of CdO. ? Vapour solid (VS) growth mechanism governs the formation of Cd nanoleaves (CdNLs). ? PL spectrum for CdNLs exhibits a strong ultraviolet (UV) emission band at 353 nm. ? UV band is attributed to interband radiative recombination under Xe illumination. -- Abstract: Multi-petal cadmium metal nanoleaves with 3040 nm thickness were fabricated on abraded copper substrate by simple thermal reduction of cadmium oxide (CdO) powder at 1050 C inside horizontal tube furnace (HTF) under nitrogen gas flow. The structural, compositional and morphological characterizations of the as-prepared cadmium nanoleaves (CdNLs) were performed by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy and selected area electron diffraction. Non-catalytic vapoursolid (VS) process based growth mechanism governing the formation of CdNLs has been proposed and discussed briefly. Photoluminescence (PL) spectrum for CdNLs measured at room temperature exhibited a single prominent emission band at 353 nm which may either be ascribed to surface oxidation effects or interband radiative recombination under Xe light illumination.

  1. Aqueous Synthesis of Zinc Blende CdTe/CdS Magic-Core/Thick-Shell

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Tetrahedral Shaped Nanocrystals with Emission Tunable to Near-Infrared Aqueous Synthesis of Zinc Blende CdTe/CdS Magic-Core/Thick-Shell Tetrahedral Shaped Nanocrystals with Emission Tunable to Near-Infrared Authors: Deng, Z., Schulz, O., Lin, S., Ding, B., Liu, X., Wei, X., Ros, R., Liu, Y., Yan, H., and Francis, M. Title: Aqueous Synthesis of Zinc Blende CdTe/CdS Magic-Core/Thick-Shell Tetrahedral Shaped Nanocrystals with Emission Tunable to Near-Infrared Source: Journal of the American

  2. Formation of Zn-rich phyllosilicate, Zn-layered double hydroxide and hydrozincite in contaminated calcareous soils

    SciTech Connect (OSTI)

    Jacquat, Olivier; Voegelin, Andreas; Villard, Andre; Marcus, Matthew A.; Kretzschmar, Ruben

    2007-10-15

    Recent studies demonstrated that Zn-phyllosilicate- and Zn-layered double hydroxide-type (Zn-LDH) precipitates may form in contaminated soils. However, the influence of soil properties and Zn content on the quantity and type of precipitate forming has not been studied in detail so far. In this work, we determined the speciation of Zn in six carbonate-rich surface soils (pH 6.2 to 7.5) contaminated by aqueous Zn in the runoff from galvanized power line towers (1322 to 30090 mg/kg Zn). Based on 12 bulk and 23 microfocused extended X-ray absorption fine structure (EXAFS) spectra, the number, type and proportion of Zn species were derived using principal component analysis, target testing, and linear combination fitting. Nearly pure Zn-rich phyllosilicate and Zn-LDH were identified at different locations within a single soil horizon, suggesting that the local availabilities of Al and Si controlled the type of precipitate forming. Hydrozincite was identified on the surfaces of limestone particles that were not in direct contact with the soil clay matrix. With increasing Zn loading of the soils, the percentage of precipitated Zn increased from {approx}20% to {approx}80%, while the precipitate type shifted from Zn-phyllosilicate and/or Zn-LDH at the lowest studied soil Zn contents over predominantly Zn-LDH at intermediate loadings to hydrozincite in extremely contaminated soils. These trends were in agreement with the solubility of Zn in equilibrium with these phases. Sequential extractions showed that large fractions of soil Zn ({approx}30% to {approx}80%) as well as of synthetic Zn-kerolite, Zn-LDH, and hydrozincite spiked into uncontaminated soil were readily extracted by 1 M NH{sub 4}NO{sub 3} followed by 1 M NH{sub 4}-acetate at pH 6.0. Even though the formation of Zn precipitates allows for the retention of Zn in excess to the adsorption capacity of calcareous soils, the long-term immobilization potential of these precipitates is limited.

  3. Development of a Solar-Thermal ZnO/Zn Water-Splitting Thermochemical...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Development of a Solar-thermal ZnOZn Water-splitting Thermochemical Cycle Final Report ... Combining this with annual average solar efficiencies, the overall solar to hydrogen LHV ...

  4. A transferable force field for CdS-CdSe-PbS-PbSe solid systems

    SciTech Connect (OSTI)

    Fan, Zhaochuan; Vlugt, Thijs J. H.; Koster, Rik S.; Fang, Changming; Huis, Marijn A. van; Wang, Shuaiwei; Yalcin, Anil O.; Tichelaar, Frans D.; Zandbergen, Henny W.

    2014-12-28

    A transferable force field for the PbSe-CdSe solid system using the partially charged rigid ion model has been successfully developed and was used to study the cation exchange in PbSe-CdSe heteronanocrystals [A. O. Yalcin et al., Atomic resolution monitoring of cation exchange in CdSe-PbSe heteronanocrystals during epitaxial solid-solid-vapor growth, Nano Lett. 14, 36613667 (2014)]. In this work, we extend this force field by including another two important binary semiconductors, PbS and CdS, and provide detailed information on the validation of this force field. The parameterization combines Bader charge analysis, empirical fitting, and ab initio energy surface fitting. When compared with experimental data and density functional theory calculations, it is shown that a wide range of physical properties of bulk PbS, PbSe, CdS, CdSe, and their mixed phases can be accurately reproduced using this force field. The choice of functional forms and parameterization strategy is demonstrated to be rational and effective. This transferable force field can be used in various studies on II-VI and IV-VI semiconductor materials consisting of CdS, CdSe, PbS, and PbSe. Here, we demonstrate the applicability of the force field model by molecular dynamics simulations whereby transformations are initiated by cation exchange.

  5. Twinning effect on photoluminescence spectra of ZnSe nanowires

    SciTech Connect (OSTI)

    Xu, Jing; Wang, Chunrui Wu, Binhe; Xu, Xiaofeng; Chen, Xiaoshuang; Oh, Hongseok; Baek, Hyeonjun; Yi, Gyu-Chul

    2014-11-07

    Bandgap engineering in a single material along the axial length of nanowires may be realized by arranging periodic twinning, whose twin plane is vertical to the axial length of nanowires. In this paper, we report the effect of twin on photoluminescence of ZnSe nanowires, which refers to the bandgap of it. The exciton-related emission peaks of transverse twinning ZnSe nanowires manifest a 10-meV-blue-shift in comparison with those of longitudinal twinning ZnSe nanowires. The blue-shift is attributed to quantum confinement effect, which is influenced severely by the proportion of wurtzite ZnSe layers in ZnSe nanowires.

  6. Development and characterization of PCDTBT:CdSe QDs hybrid solar cell

    SciTech Connect (OSTI)

    Dixit, Shiv Kumar Bhatnagar, Chhavi Kumari, Anita Madhwal, Devinder Bhatnagar, P. K. Mathur, P. C.

    2014-10-15

    Solar cell consisting of low band gap polymer poly[N-900-hepta-decanyl-2,7-carbazole-alt-5,5-(40,70-di-2-thienyl-20,10, 30-benzothiadiazole)] (PCDTBT) as donor and cadmium selenide/zinc sulphide (CdSe/ZnS) core shell quantum dots (QDs) as an acceptor has been developed. The absorption measurements show that the absorption coefficient increases in bulk heterojunction (BHJ) structure covering broad absorption spectrum (200nm–700nm). Also, the photoluminescence (PL) of the PCDTBT:QDs film is found to decrease by an order of magnitude showing a significant transfer of electrons to the QDs. With this approach and under broadband white light with an irradiance of 8.19 mW/cm{sup 2}, we have been able to achieve a power conversion efficiency (PCE) of 3.1 % with fill factor 0.42 for our typical solar cell.

  7. High-Efficiency Polycrystalline CdTe Thin-Film Solar Cells with an Oxygenated Amorphous CdS (a-CdS:O) Window Layer: Preprint

    SciTech Connect (OSTI)

    Wu, X.; Dhere, R. G.; Yan, Y.; Romero, M. J.; Zhang, Y.; Zhou, J.; DeHart, C.; Duda, A.; Perkins, C.; To, B.

    2002-05-01

    In the conventional CdS/CdTe device structure, the poly-CdS window layer has a bandgap of {approx}2.4 eV, which causes absorption in the short-wavelength region. Higher short-circuit current densities (Jsc) can be achieved by reducing the CdS thickness, but this can adversely impact device open-circuit voltage (Voc) and fill factor (FF). Also, poly-CdS film has about 10% lattice mismatch related to the CdTe film, which limits the improvement of device Voc and FF. In this paper, we report a novel window material: oxygenated amorphous CdS film (a-CdS:O) prepared at room temperature by rf sputtering. The a-CdS:O film has a higher optical bandgap (2.5-3.1 eV) than the poly-CdS film and an amorphous structure. The preliminary device results have demonstrated that Jsc of the CdTe device can be greatly improved while maintaining higher Voc and FF. We have fabricated a CdTe cell demonstrating an NREL-confirmed Jsc of 25.85 mA/cm2 and a total-area efficiency of 15.4%.

  8. cd ordering | netl.doe.gov

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    CD-DVD Ordering System Please complete the following information so the National Energy Technology Lab (NETL) can promptly process your order. Below is a sample of the fields required to order a CD or DVD. If any fields are left blank you may not receive your disk. Data gathered by this form will be used only by the NETL. and will not be distributed for any other purpose. Data transferred via the Internet to this database should not be considered secure. Last Name: Doe First Name: John Middle

  9. Nanowire CdS-CdTe solar cells with molybdenum oxide as contact

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dang, Hongmei; Singh, Vijay P.

    2015-10-06

    Using a 10 nm thick molybdenum oxide (MoO3-x) layer as a transparent and low barrier contact to p-CdTe, we demonstrate nanowire CdS-CdTe solar cells with a power conversion efficiency of 11% under front side illumination. Annealing the as-deposited MoO3 film in N2 resulted in a reduction of the cell’s series resistance, from 9.97 Ω/cm2 to 7.69 Ω/cm2, and increase in efficiency from 9.9% to 11%. Under illumination from the back, the MoO3-x/Au side, the nanowire solar cells yielded Jsc of 21 mA/cm2 and efficiency of 8.67%. Our results demonstrate use of a thin layer transition metal oxide as a potentialmore » way for a transparent back contact to nanowire CdS-CdTe solar cells. As a result, this work has implications toward enabling a novel superstrate structure nanowire CdS-CdTe solar cell on Al foil substrate by a low cost roll-to roll fabrication process.« less

  10. Nanowire CdS-CdTe solar cells with molybdenum oxide as contact

    SciTech Connect (OSTI)

    Dang, Hongmei; Singh, Vijay P.

    2015-10-06

    Using a 10 nm thick molybdenum oxide (MoO3-x) layer as a transparent and low barrier contact to p-CdTe, we demonstrate nanowire CdS-CdTe solar cells with a power conversion efficiency of 11% under front side illumination. Annealing the as-deposited MoO3 film in N2 resulted in a reduction of the cell’s series resistance, from 9.97 Ω/cm2 to 7.69 Ω/cm2, and increase in efficiency from 9.9% to 11%. Under illumination from the back, the MoO3-x/Au side, the nanowire solar cells yielded Jsc of 21 mA/cm2 and efficiency of 8.67%. Our results demonstrate use of a thin layer transition metal oxide as a potential way for a transparent back contact to nanowire CdS-CdTe solar cells. As a result, this work has implications toward enabling a novel superstrate structure nanowire CdS-CdTe solar cell on Al foil substrate by a low cost roll-to roll fabrication process.

  11. Director's CD-2/CD-3a Review of the MINERnA Project

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Director's CD-2/CD-3a Review of the MINERnA Project Main INjector ExpeRiment v-A August 1-3, 2006 | Overview | General Reference Material | CD-2/3a Documentation| Link to the Directorate Web Page for this review Review Overview Information Charge to the Committee (pdf) Agenda (pdf - with links to all of the plenary and breakout sessions) List of Prepared Breakout Talks (pdf) Review Committee (pdf) Video and Phone Connection Numbers Information for Visitors Bringing Laptops to Fermilab (doc)

  12. Impact of air-exposure on the chemical and electronic structure ofZnO:Zn3N2 thin films

    SciTech Connect (OSTI)

    Bar, M.; Ahn, K.-S.; Shet, S.; Yan, Y.; Weinhardt, L.; Fuchs, O.; Blum, M.; Pookpanratana, S.; George, K.; Yang, W.; Denlinger, J.D.; Al-Jassim, M.; Heske, C.

    2008-09-08

    The chemical and electronic surface structure of ZnO:Zn3N2 ("ZnO:N") thin films with different N contents was investigated by soft x-ray emission spectroscopy. Upon exposure to ambient air (in contrast to storage in vacuum), the chemical and electronic surface structure of the ZnO:N films changes substantially. In particular, we find that the Zn3N2/(Zn3N2+ZnO) ratio decreases with exposure time and that this change depends on the initial N content. We suggest a degradation mechanism based on the reaction of the Zn3N2 content with atmospheric humidity.

  13. Determination of CdTe bulk carrier lifetime and interface recombination velocity of CdTe/MgCdTe double heterostructures grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Zhao, Xin-Hao; Campbell, Calli M.; DiNezza, Michael J.; Liu, Shi; Zhao, Yuan; Zhang, Yong-Hang

    2014-12-22

    The bulk Shockley-Read-Hall carrier lifetime of CdTe and interface recombination velocity at the CdTe/Mg{sub 0.24}Cd{sub 0.76}Te heterointerface are estimated to be around 0.5??s and (4.7??0.4)??10{sup 2?}cm/s, respectively, using time-resolved photoluminescence (PL) measurements. Four CdTe/MgCdTe double heterostructures (DHs) with varying CdTe layer thicknesses were grown on nearly lattice-matched InSb (001) substrates using molecular beam epitaxy. The longest lifetime of 179?ns is observed in the DH with a 2??m thick CdTe layer. It is also shown that the photon recycling effect has a strong influence on the bulk radiative lifetime, and the reabsorption process affects the measured PL spectrum shape and intensity.

  14. Spin noise spectroscopy of ZnO

    SciTech Connect (OSTI)

    Horn, H.; Berski, F.; Hbner, J.; Oestreich, M.; Balocchi, A.; Marie, X.; Mansur-Al-Suleiman, M.; Bakin, A.; Waag, A.

    2013-12-04

    We investigate the thermal equilibrium dynamics of electron spins bound to donors in nanoporous ZnO by optical spin noise spectroscopy. The spin noise spectra reveal two noise contributions: A weak spin noise signal from undisturbed localized donor electrons with a dephasing time of 24 ns due to hyperfine interaction and a strong spin noise signal with a spin dephasing time of 5 ns which we attribute to localized donor electrons which interact with lattice defects.

  15. I-III-VI.sub.2 based solar cell utilizing the structure CuInGaSe.sub.2 CdZnS/ZnO

    DOE Patents [OSTI]

    Chen, Wen S.; Stewart, John M.

    1992-01-07

    A thin film I-III-VI.sub.2 based solar cell having a first layer of copper indium gallium selenide, a second layer of cadmium zinc sulfide, a double layer of zinc oxide, and a metallization structure comprised of a layer of nickel covered by a layer of aluminum. An optional antireflective coating may be placed on said metallization structure. The cadmium zinc sulfide layer is deposited by means of an aqueous solution growth deposition process and may actually consist of two layers: a low zinc content layer and a high zinc content layer. Photovoltaic efficiencies of 12.5% at Air Mass 1.5 illumination conditions and 10.4% under AMO illumination can be achieved.

  16. Photoluminescence studies of type-II CdSe/CdTe superlattices

    SciTech Connect (OSTI)

    Li Jingjing; Johnson, Shane R.; Wang Shumin; Ding Ding; Ning Cunzheng; Zhang Yonghang; Yin Leijun; Skromme, B. J.; Liu Xinyu; Furdyna, Jacek K.

    2012-08-06

    CdSe/CdTe type-II superlattices grown on GaSb substrates by molecular beam epitaxy are studied using time-resolved and steady-state photoluminescence (PL) spectroscopy at 10 K. The relatively long carrier lifetime of 188 ns observed in time-resolved PL measurements shows good material quality. The steady-state PL peak position exhibits a blue shift with increasing excess carrier concentration. Self-consistent solutions of the Schroedinger and Poisson equations show that this effect can be explained by band bending as a result of the spatial separation of electrons and holes, which is critical confirmation of a strong type-II band edge alignment between CdSe and CdTe.

  17. Broadening of optical transitions in polycrystalline CdS and CdTe thin films

    SciTech Connect (OSTI)

    Li Jian; Chen Jie; Collins, R. W.

    2010-11-01

    The dielectric functions {epsilon} of polycrystalline CdS and CdTe thin films sputter deposited onto Si wafers were measured from 0.75 to 6.5 eV by in situ spectroscopic ellipsometry. Differences in {epsilon} due to processing variations are well understood using an excited carrier scattering model. For each sample, a carrier mean free path {lambda} is defined that is found to be inversely proportional to the broadening of each of the band structure critical points (CPs) deduced from {epsilon}. The rate at which broadening occurs with {lambda}{sup -1} is different for each CP, enabling a carrier group speed {upsilon}{sub g} to be identified for the CP. With the database for {upsilon}{sub g}, {epsilon} can be analyzed to evaluate the quality of materials used in CdS/CdTe photovoltaic heterojunctions.

  18. Integrated Biorefinery Research Facility (IBRF I-II) (Post CD...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Integrated Biorefinery Research Facility (IBRF I-II) (Post CD-4), EERE, Aug 2011 Integrated Biorefinery Research Facility (IBRF I-II) (Post CD-4), EERE, Aug 2011 PDF icon 000521 & ...

  19. Buckeye Water C&D District | Open Energy Information

    Open Energy Info (EERE)

    Buckeye Water C&D District Jump to: navigation, search Name: Buckeye Water C&D District Place: Arizona Phone Number: 623-386-2196 Website: www.bwcdd.com Outage Hotline: Upper...

  20. CD-3, Approve Start of Construction/Execution

    Broader source: Energy.gov [DOE]

    CD-3 is a continuation of the execution phase. The project is ready to complete all construction, implementation, procurement, fabrication, acceptance and turnover activities. Table 2.3 lists the requirements needed to attain CD-3.

  1. Buckeye Water C&D District | Open Energy Information

    Open Energy Info (EERE)

    Buckeye Water C&D District (Redirected from Buckeye Irrigation District) Jump to: navigation, search Name: Buckeye Water C&D District Place: Arizona Phone Number: 623-386-2196...

  2. Wind Energy Resource Atlas of Armenia (CD-ROM)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Resource Atlas of Armenia (CD-ROM) http:www.nrel.govdocsfy03osti33877CD.zip (ZIP 31.9 MB) NRELCD-500-33877 July 2003 Instructions: The URL above links to a zipped archive...

  3. C.D. Howe Institute | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    C.D. Howe Institute C.D. Howe Institute October 21, 2008 - 4:14pm Addthis Remarks as Prepared for Acting Deputy Secretary Kupfer Thank you very much. It's a pleasure to be here. I ...

  4. Stable highly conductive ZnO via reduction of Zn vacancies

    SciTech Connect (OSTI)

    Look, David C.; Droubay, Timothy C.; Chambers, Scott A.

    2012-09-04

    Growth of Ga-doped ZnO by pulsed laser deposition at 200 ?C in an ambient of Ar and H2 produces a resistivity ? of ~ 1.5 x 10-4 ?-cm, stable to 500 ?C. Annealing on Zn foil reduces ? to ~ 1.2 x 10-4 ?-cm, one of the lowest values ever reported. The key is reducing the Zn-vacancy acceptor concentration NA to 5 x 1019, only 3% of the Ga-donor concentration ND of 1.6 x 1021 cm-3, with ND and NA determined from a degenerate mobility theory. The plasmonic wavelength is 1060 nm, further bridging the gap between metals and semiconductors.

  5. CD Label and Package Templates | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Publications, Exhibits, & Logos » Templates » CD Label and Package Templates CD Label and Package Templates The Office of Energy Efficiency and Renewable Energy (EERE) has developed templates for CD labels and CD packages. These can be used for all EERE products. Both templates are available as EPS files, which can be downloaded and edited in a graphics package like Adobe Illustrator. You are not required to use these templates for your EERE products. These templates were designed to allow

  6. Anisotropy in CdSe quantum rods

    SciTech Connect (OSTI)

    Li, Liang-shi

    2003-09-01

    The size-dependent optical and electronic properties of semiconductor nanocrystals have drawn much attention in the past decade, and have been very well understood for spherical ones. The advent of the synthetic methods to make rod-like CdSe nanocrystals with wurtzite structure has offered us a new opportunity to study their properties as functions of their shape. This dissertation includes three main parts: synthesis of CdSe nanorods with tightly controlled widths and lengths, their optical and dielectric properties, and their large-scale assembly, all of which are either directly or indirectly caused by the uniaxial crystallographic structure of wurtzite CdSe. The hexagonal wurtzite structure is believed to be the primary reason for the growth of CdSe nanorods. It represents itself in the kinetic stabilization of the rod-like particles over the spherical ones in the presence of phosphonic acids. By varying the composition of the surfactant mixture used for synthesis we have achieved tight control of the widths and lengths of the nanorods. The synthesis of monodisperse CdSe nanorods enables us to systematically study their size-dependent properties. For example, room temperature single particle fluorescence spectroscopy has shown that nanorods emit linearly polarized photoluminescence. Theoretical calculations have shown that it is due to the crossing between the two highest occupied electronic levels with increasing aspect ratio. We also measured the permanent electric dipole moment of the nanorods with transient electric birefringence technique. Experimental results on nanorods with different sizes show that the dipole moment is linear to the particle volume, indicating that it originates from the non-centrosymmetric hexagonal lattice. The elongation of the nanocrystals also results in the anisotropic inter-particle interaction. One of the consequences is the formation of liquid crystalline phases when the nanorods are dispersed in solvent to a high enough concentration. The preparation of the stable liquid crystalline solution of CdSe nanorods is described, as well as the large-scale alignment of the nanorods by taking advantage of the long-range orientational correlation in the liquid crystals. In addition, we investigated the phase diagram of the nanorod solution, as a step toward understanding the possible role of the long-range attractive interaction between the nanorods in the formation of lyotropic liquid crystals.

  7. Optical probing of MgZnO/ZnO heterointerface confinement potential energy levels

    SciTech Connect (OSTI)

    Solovyev, V. V.; Van'kov, A. B.; Kukushkin, I. V.; Falson, J.; Kozuka, Y.; Zhang, D.; Smet, J. H.; Maryenko, D.; Tsukazaki, A.; Kawasaki, M.

    2015-02-23

    Low-temperature photoluminescence and reflectance measurements were employed to study the optical transitions present in two-dimensional electron systems confined at Mg{sub x}Zn{sub 1x}O/ZnO heterojunctions. Transitions involving A- and B-holes and electrons from the two lowest subbands formed within the confinement potential are detected. In the studied density range of 2.06.5??10{sup 11?}cm{sup ?2}, the inter-subband splitting is measured and the first excited electron subband is shown to be empty of electrons.

  8. CdSe/CdTe type-II superlattices grown on GaSb (001) substrates by molecular beam epitaxy

    SciTech Connect (OSTI)

    Li Jingjing; Liu Shi; Wang Shumin; Ding Ding; Johnson, Shane R.; Zhang Yonghang; Liu Xinyu; Furdyna, Jacek K.; Smith, David J.

    2012-03-19

    CdSe/CdTe superlattices are grown on GaSb substrates using molecular beam epitaxy. X-ray diffraction measurements and cross-sectional transmission electron microscopy images indicate high crystalline quality. Photoluminescence (PL) measurements show the effective bandgap varies with the superlattice layer thicknesses and confirm the CdSe/CdTe heterostructure has a type-II band edge alignment. The valence band offset between unstrained CdTe and CdSe is determined as 0.63 {+-} 0.06 eV by fitting the measured PL peak positions using the envelope function approximation and the Kronig-Penney model. These results suggest that CdSe/CdTe superlattices are promising candidates for multi-junction solar cells and other optoelectronic devices based on GaSb substrates.

  9. Optical Properties of ZnO-Alloyed Nanocrystalline Films

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Che, Hui; Huso, Jesse; Morrison, John L.; Thapa, Dinesh; Huso, Michelle; Yeh, Wei Jiang; Tarun, M. C.; McCluskey, M. D.; Bergman, Leah

    2012-01-01

    ZnO is emore » merging as one of the materials of choice for UV applications. It has a deep excitonic energy level and a direct bandgap of ~3.4 eV. Alloying ZnO with certain atomic constituents adds new optical and electronic functionalities to ZnO. This paper presents research on M g x Z n 1 − x O and Z n S 1 − x O x nanocrystalline flexible films, which enable tunable optical properties in the deep-UV and in the visible range. The ZnO and Mg 0 .3 Zn 0 .7 O films were found to have bandgaps at 3.35 and 4.02 eV, respectively. The photoluminescence of the Mg 0 .3 Zn 0 .7 O exhibited a bandedge emission at 3.95 eV, and at lower energy 3.38 eV due to the limited solubility inherent to these alloys. ZnS 0 .76 O 0 .24 and ZnS 0 .16 O 0 .84 were found to have bandgaps at 3.21 and 2.65 eV, respectively. The effect of nitrogen doping on ZnS 0 .16 O 0 .84 is discussed in terms of the highly lattice mismatched nature of these alloys and the resulting valence-band modification.« less

  10. Evolution of quasiparticle states with and without a Zn impurity...

    Office of Scientific and Technical Information (OSTI)

    Evolution of quasiparticle states with and without a Zn impurity in doped 122 iron pnictides Citation Details In-Document Search Title: Evolution of quasiparticle states with and ...

  11. Piezoelectric and luminescent properties of ZnO nanostructures...

    Office of Scientific and Technical Information (OSTI)

    Title: Piezoelectric and luminescent properties of ZnO nanostructures on Ag films. No abstract prepared. Authors: Tallant, David Robert ; Missert, Nancy A. ; Scrymgeour, David ; ...

  12. FERMILAB-PUB-15-596-CD

    Office of Scientific and Technical Information (OSTI)

    FERMILAB-PUB-15-596-CD Available on CMS information server CMS CR -2015/088 The Compact Muon Solenoid Experiment Conference Report Mailing address: CMS CERN, CH-1211 GENEVA 23, Switzerland 17 May 2015 Comprehensive Monitoring for Heterogeneous Geographically Distributed Storage. Tony Wildish, Natalia Ratnikova, Stephen Lammel, Edward karavakis for the CMS Collaboration Abstract Storage capacity at CMS Tier-1 and Tier-2 sites reached over 100 Petabytes in 2014, and will be substantially increased

  13. Copper migration in CdTe heterojunction solar cells

    SciTech Connect (OSTI)

    Chou, H.C.; Rohatgi, A.; Jokerst, N.M.; Thomas, E.W.; Kamra, S.

    1996-07-01

    CdTe solar cells were fabricated by depositing a Au/Cu contact with Cu thickness in the range of 50 to 150A on polycrystalline CdTe/CdS/SnO{sub 2} glass structures. The increase in Cu thickness improves ohmic contact and reduces series resistance (R{sub s}), but the excess Cu tends to diffuse into CdTe and lower shunt resistance (R{sub sh}) and cell performance. Light I-V and secondary ion mass spectroscopy (SIMS) measurements were performed to understand the correlations between the Cu contact thickness, the extent of Cu incorporation in the CdTe cells, and its impact on the cell performance. The CdTe/CdS/SnO{sub 2} glass, CdTe/CdS/GaAs, and CdTe/GaAs structures were prepared in an attempt to achieve CdTe films with different degrees of crystallinity and grain size. A large grain polycrystalline CdTe thin film solar cell was obtained for the first time by selective etching the GaAs substrate coupled with the film transfer onto a glass substrate. SIMS measurement showed that poor crystallinity and smaller grain size of the CdTe film promotes Cu diffusion and decreases the cell performance. Therefore, grain boundaries are the main conduits for Cu migration and larger CdTe grain size or alternate method of contact formation can mitigate the adverse effect of Cu and improve the cell performance. 15 refs., 1 fig.,6 tabs.

  14. Hierarchical ZnO Structures Templated with Amino Acid Based Surfactant...

    Office of Scientific and Technical Information (OSTI)

    Hierarchical ZnO Structures Templated with Amino Acid Based Surfactants Citation Details In-Document Search Title: Hierarchical ZnO Structures Templated with Amino Acid Based ...

  15. Enhancement of photoluminescence properties in ZnO/AlN bilayer...

    Office of Scientific and Technical Information (OSTI)

    in ZnOAlN bilayer heterostructures grown by atomic layer deposition Citation Details In-Document Search Title: Enhancement of photoluminescence properties in ZnOAlN ...

  16. Neutral nitrogen acceptors in ZnO: The {sup 67}Zn hyperfine interactions

    SciTech Connect (OSTI)

    Golden, E. M.; Giles, N. C.; Evans, S. M.; Halliburton, L. E.

    2014-03-14

    Electron paramagnetic resonance (EPR) is used to characterize the {sup 67}Zn hyperfine interactions associated with neutral nitrogen acceptors in zinc oxide. Data are obtained from an n-type bulk crystal grown by the seeded chemical vapor transport method. Singly ionized nitrogen acceptors (N{sup −}) initially present in the crystal are converted to their paramagnetic neutral charge state (N{sup 0}) during exposure at low temperature to 442 or 633 nm laser light. The EPR signals from these N{sup 0} acceptors are best observed near 5 K. Nitrogen substitutes for oxygen ions and has four nearest-neighbor cations. The zinc ion along the [0001] direction is referred to as an axial neighbor and the three equivalent zinc ions in the basal plane are referred to as nonaxial neighbors. For axial neighbors, the {sup 67}Zn hyperfine parameters are A{sub ‖} = 37.0 MHz and A{sub ⊥} = 8.4 MHz with the unique direction being [0001]. For nonaxial neighbors, the {sup 67}Zn parameters are A{sub 1} = 14.5 MHz, A{sub 2} = 18.3 MHz, and A{sub 3} = 20.5 MHz with A{sub 3} along a [101{sup ¯}0] direction (i.e., in the basal plane toward the nitrogen) and A{sub 2} along the [0001] direction. These {sup 67}Zn results and the related {sup 14}N hyperfine parameters provide information about the distribution of unpaired spin density at substitutional neutral nitrogen acceptors in ZnO.

  17. Evidence of significant down-conversion in a Si-based solar cell using CuInS{sub 2}/ZnS core shell quantum dots

    SciTech Connect (OSTI)

    Gardelis, Spiros Nassiopoulou, Androula G.

    2014-05-05

    We report on the increase of up to 37.5% in conversion efficiency of a Si-based solar cell after deposition of light-emitting Cd-free, CuInS{sub 2}/ZnS core shell quantum dots on the active area of the cell due to the combined effect of down-conversion and the anti- reflecting property of the dots. We clearly distinguished the effect of down-conversion from anti-reflection and estimated an enhancement of up to 10.5% in the conversion efficiency due to down-conversion.

  18. Radiative lifetimes of zincblende CdSe/CdS quantum dots

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gong, Ke; Martin, James E.; Shea-Rohwer, Lauren E.; Lu, Ping; Kelley, David F.

    2015-01-02

    Recent synthetic advances have made available very monodisperse zincblende CdSe/CdS quantum dots having near-unity photoluminescence quantum yields. Because of the absence of nonradiative decay pathways, accurate values of the radiative lifetimes can be obtained from time-resolved PL measurements. Radiative lifetimes can also be obtained from the Einstein relations, using the static absorption spectra and the relative thermal populations in the angular momentum sublevels. We found that one of the inputs into these calculations is the shell thickness, and it is useful to be able to determine shell thickness from spectroscopic measurements. We use an empirically corrected effective mass model tomore » produce a “map” of exciton wavelength as a function of core size and shell thickness. These calculations use an elastic continuum model and the known lattice and elastic constants to include the effect of lattice strain on the band gap energy. The map is in agreement with the known CdSe sizing curve and with the shell thicknesses of zincblende core/shell particles obtained from TEM images. Furthermore, if selenium–sulfur diffusion is included and lattice strain is omitted from the calculation then the resulting map is appropriate for wurtzite CdSe/CdS quantum dots synthesized at high temperatures, and this map is very similar to one previously reported (J. Am. Chem. Soc. 2009, 131, 14299). Radiative lifetimes determined from time-resolved measurements are compared to values obtained from the Einstein relations, and found to be in excellent agreement. For a specific core size (2.64 nm diameter, in the present case), radiative lifetimes are found to decrease with increasing shell thickness. Thus, this is similar to the size dependence of one-component CdSe quantum dots and in contrast to the size dependence in type-II quantum dots.« less

  19. Radiative lifetimes of zincblende CdSe/CdS quantum dots

    SciTech Connect (OSTI)

    Gong, Ke; Martin, James E.; Shea-Rohwer, Lauren E.; Lu, Ping; Kelley, David F.

    2015-01-02

    Recent synthetic advances have made available very monodisperse zincblende CdSe/CdS quantum dots having near-unity photoluminescence quantum yields. Because of the absence of nonradiative decay pathways, accurate values of the radiative lifetimes can be obtained from time-resolved PL measurements. Radiative lifetimes can also be obtained from the Einstein relations, using the static absorption spectra and the relative thermal populations in the angular momentum sublevels. We found that one of the inputs into these calculations is the shell thickness, and it is useful to be able to determine shell thickness from spectroscopic measurements. We use an empirically corrected effective mass model to produce a “map” of exciton wavelength as a function of core size and shell thickness. These calculations use an elastic continuum model and the known lattice and elastic constants to include the effect of lattice strain on the band gap energy. The map is in agreement with the known CdSe sizing curve and with the shell thicknesses of zincblende core/shell particles obtained from TEM images. Furthermore, if selenium–sulfur diffusion is included and lattice strain is omitted from the calculation then the resulting map is appropriate for wurtzite CdSe/CdS quantum dots synthesized at high temperatures, and this map is very similar to one previously reported (J. Am. Chem. Soc. 2009, 131, 14299). Radiative lifetimes determined from time-resolved measurements are compared to values obtained from the Einstein relations, and found to be in excellent agreement. For a specific core size (2.64 nm diameter, in the present case), radiative lifetimes are found to decrease with increasing shell thickness. Thus, this is similar to the size dependence of one-component CdSe quantum dots and in contrast to the size dependence in type-II quantum dots.

  20. Mobility of indium on the ZnO(0001) surface

    SciTech Connect (OSTI)

    Heinhold, R.; Reeves, R. J.; Allen, M. W.; Williams, G. T.; Evans, D. A.

    2015-02-02

    The mobility of indium on the Zn-polar (0001) surface of single crystal ZnO wafers was investigated using real-time x-ray photoelectron spectroscopy. A sudden transition in the wettability of the ZnO(0001) surface was observed at ∼520 °C, with indium migrating from the (0001{sup ¯}) underside of the wafer, around the non-polar (11{sup ¯}00) and (112{sup ¯}0) sidewalls, to form a uniform self-organized (∼20 Å) adlayer. The In adlayer was oxidized, in agreement with the first principles calculations of Northrup and Neugebauer that In{sub 2}O{sub 3} precipitation can only be avoided under a combination of In-rich and Zn-rich conditions. These findings suggest that unintentional In adlayers may form during the epitaxial growth of ZnO on indium-bonded substrates.

  1. OPTIMIZATION OF VIRTUAL FRISCH-GRID CdZnTe DETECTOR DESIGNS FOR IMAGING AND SPECTROSCOPY OF GAMMA RAYS.

    SciTech Connect (OSTI)

    BOLOTNIKOV,A.E.; ABDUL-JABBAR, N.M.; BABALOLA, S.; CAMARDA, G.S.; CUI, Y.; HOSSAIN, A.; JACKSON, E.; JACKSON, H.; JAMES, J.R.; LURYI, A.L.; JAMES, R.B.

    2007-08-21

    In the past, various virtual Frisch-grid designs have been proposed for cadmium zinc telluride (CZT) and other compound semiconductor detectors. These include three-terminal, semi-spherical, CAPture, Frisch-ring, capacitive Frisch-grid and pixel devices (along with their modifications). Among them, the Frisch-grid design employing a non-contacting ring extended over the entire side surfaces of parallelepiped-shaped CZT crystals is the most promising. The defect-free parallelepiped-shaped crystals with typical dimensions of 5x5{approx}12 mm3 are easy to produce and can be arranged into large arrays used for imaging and gamma-ray spectroscopy. In this paper, we report on further advances of the virtual Frisch-grid detector design for the parallelepiped-shaped CZT crystals. Both the experimental testing and modeling results are described.

  2. Modification of solid state CdZnTe (CZT) radiation detectors with high sensitivity or high resolution operation

    DOE Patents [OSTI]

    Washington, II, Aaron L; Duff, Martine C; Teague, Lucile C; Burger, Arnold; Groza, Michael

    2014-11-11

    An apparatus and process is provided to illustrate the manipulation of the internal electric field of CZT using multiple wavelength light illumination on the crystal surface at RT. The control of the internal electric field is shown through the polarization in the IR transmission image under illumination as a result of the Pockels effect.

  3. Characterization of electrospray ion-beam-deposited CdSe/ZnS quantum dot thin films from a colloidal solution

    SciTech Connect (OSTI)

    Tani, Yuki; Kobayashi, Satoshi; Kawazoe, Hiroshi

    2008-07-15

    Colloidal semiconductor quantum dot (QD) nanocrystals can be deposited in the form of inorganic thin films using the ion beam direct deposition method. To simultaneously preserve the nanocrystal configuration and remove the organics derived from the ligand and solvent, the authors used an electrospray technique and an ion beam technique. These techniques provided a soft-ionization process to obtain nanocrystalline ions and a collision process to attain a nonequilibrium state of the deposits, respectively. Because of the nature of the soft-ionization process, the electrospray phenomenon resulted in various forms of QD ions that depended on the preparation of the colloidal solution source and spraying conditions. The authors concentrated on finding operational conditions of the system that deposited thin films with reduced organics concentrations by examining the correlation between fast Fourier transform infrared absorption spectroscopy and photoluminescence intensity. The morphology of the deposited films was observed using an atomic force microscope.

  4. Current enhancement of CdTe-based solar cells

    SciTech Connect (OSTI)

    Paudel, Naba R.; Poplawsky, Jonathan D.; More, Karren Leslie; Yan, Yanfa

    2015-07-30

    We report on the realization of CdTe solar cell photocurrent enhancement using an n-type CdSe heterojunction partner sputtered on commercial SnO2/SnO2:F coated soda-lime glass substrates. With high-temperature close-space sublimation CdTe deposition followed by CdCl2 activation, this thin-film stack allows for substantial interdiffusion at the CdSe/CdTe interface facilitating a CdSexTe1-x alloy formation. The bowing effect causes a reduced optical bandgap of the alloyed absorber layer and, therefore, leads to current enhancement in the long-wavelength region and a decrease in open-circuit voltage (VOC). To overcome the VOC loss and maintain a high short-circuit current (JSC), the CdTe cell configuration has been modified using combined CdS:O/CdSe window layers. The new device structure has demonstrated enhanced collection from both short-and long-wavelength regions as well as a VOC improvement. With an optimized synthesis process, a small-area cell using CdS:O/CdSe window layer showed an efficiency of 15.2% with a VOC of 831 mV, a JSC of 26.3 mA/cm2, and a fill factor of 69.5%, measured under an AM1.5 illumination without antireflection coating. Furthermore, the results provide new directions for further improvement of CdTe-based solar cells.

  5. Current enhancement of CdTe-based solar cells

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Paudel, Naba R.; Poplawsky, Jonathan D.; More, Karren Leslie; Yan, Yanfa

    2015-07-30

    We report on the realization of CdTe solar cell photocurrent enhancement using an n-type CdSe heterojunction partner sputtered on commercial SnO2/SnO2:F coated soda-lime glass substrates. With high-temperature close-space sublimation CdTe deposition followed by CdCl2 activation, this thin-film stack allows for substantial interdiffusion at the CdSe/CdTe interface facilitating a CdSexTe1-x alloy formation. The bowing effect causes a reduced optical bandgap of the alloyed absorber layer and, therefore, leads to current enhancement in the long-wavelength region and a decrease in open-circuit voltage (VOC). To overcome the VOC loss and maintain a high short-circuit current (JSC), the CdTe cell configuration has been modifiedmore » using combined CdS:O/CdSe window layers. The new device structure has demonstrated enhanced collection from both short-and long-wavelength regions as well as a VOC improvement. With an optimized synthesis process, a small-area cell using CdS:O/CdSe window layer showed an efficiency of 15.2% with a VOC of 831 mV, a JSC of 26.3 mA/cm2, and a fill factor of 69.5%, measured under an AM1.5 illumination without antireflection coating. Furthermore, the results provide new directions for further improvement of CdTe-based solar cells.« less

  6. Stimulated electroluminescence emission from n-ZnO/p-GaAs:Zn heterojunctions fabricated by electro-deposition

    SciTech Connect (OSTI)

    K, P.; Tekmen, S.; Baltakesmez, A.; Tzemen, S.; Meral, K.; Onganer, Y.

    2013-12-15

    In this study, n-ZnO thin films were electrochemically deposited on p-GaAs:Zn substrates. The XRD results of ZnO thin films deposited on p-GaAs:Zn substrates at potentials varied from ?0.9 V to ?1.2 V show a strong c-axis (002) orientation and homogeneity. The current-voltage characteristics exhibit rectification, proving a low turn-on voltage and an ideality factor of 4.71. The n-ZnO/p-GaAs heterostructures show blue-white electroluminescence (EL) emission, which is composed of broad emission bands. In addition to these broad peaks, stimulated emission also appear on the top of the spectra due to the multiple reflections from the mirror like surfaces of ZnO-ZnO and ZnO-GaAs interfaces. Besides, three broad photoluminescence (PL) emission peaks have also been observed peaking at respectively around 3.36 eV, 3.28 eV and 3.07 eV generally attributed to the near bandedge emission, the residual donor level and deep level emission due to the localized defects, respectively.

  7. ZnO/Cu(InGa)Se.sub.2 solar cells prepared by vapor phase Zn doping

    DOE Patents [OSTI]

    Ramanathan, Kannan; Hasoon, Falah S.; Asher, Sarah E.; Dolan, James; Keane, James C.

    2007-02-20

    A process for making a thin film ZnO/Cu(InGa)Se.sub.2 solar cell without depositing a buffer layer and by Zn doping from a vapor phase, comprising: depositing Cu(InGa)Se.sub.2 layer on a metal back contact deposited on a glass substrate; heating the Cu(InGa)Se.sub.2 layer on the metal back contact on the glass substrate to a temperature range between about 100.degree. C. to about 250.degree. C.; subjecting the heated layer of Cu(InGa)Se.sub.2 to an evaporant species from a Zn compound; and sputter depositing ZnO on the Zn compound evaporant species treated layer of Cu(InGa)Se.sub.2.

  8. The role of intrahepatic CD3 +/CD4 −/CD8 − double negative T (DN T) cells in enhanced acetaminophen toxicity

    SciTech Connect (OSTI)

    Getachew, Yonas; Cusimano, Frank A.; James, Laura P.; Thiele, Dwain L.

    2014-10-15

    The role of the immune system, specifically NK, NKT and CD3 cells, in acetaminophen (APAP) induced liver injury remains inconsistently defined. In the present study, wild type (C57BL/6J) mice and granzyme B deficient (GrB −/−) mice were treated with acetaminophen to assess the role of the immune system in acute liver injury. Doses of acetaminophen that induced sub lethal liver injury in wild type mice unexpectedly produced fatal hepatotoxicity in granzyme B deficient (GrB −/−) mice. Analysis revealed that GrB −/− mice had an increased population of intrahepatic CD3 (+), CD4 (−), and CD8 (−) lymphocytes expressing the CD69 activation marker and Fas ligand. Depletion of these cells in the GrB −/− and wild type mice made them less susceptible to APAP injury, while depletion of NK1.1 (+) cells or both CD4 (+) and CD8 (+) T cells failed to provide the same hepatoprotection. Transfer of the GrB −/− IHLs further exacerbated liver injury and increased mortality in wild type mice but not in LRP/LPR mice, lacking fas expression. Conclusions: Acetaminophen toxicity is enhanced by the presence of activated, FasL expressing intrahepatic CD3 (+), CD4 (−), CD8 (−), NK1.1 (−) T cells. Depletion of these cells from GrB −/− mice and wild type mice greatly reduces mortality and improves the course of liver injury recovery. - Highlights: • Intrahepatic lymphocytes (IHLs) from GrB −/− mice harbor activated DNT cells. • IHLs from GrB −/− mice exhibit enhanced Fas ligand expression. • Acetaminophen toxicity is enhanced by activated, FasL expressing DNT cells.

  9. Development of CdS/CdTe Tin Film Devices for St. Gobain Coated Glass: Cooperative Research and Development Final Report, CRADA Number CRD-08-317

    SciTech Connect (OSTI)

    Gessert, T.

    2012-04-01

    Research performed at NREL to produce CdS/CdTe devices on St. Gobain coated-glass material to establish a baseline CdS/CdTe device process and determine baseline device performance parameters on St. Gobain material. Performance of these baseline devices compared to similar devices produced by applying the established baseline CdS/CdTe process on alternative St. Gobain coated-glass materials.

  10. Air-gap gating of MgZnO/ZnO heterostructures

    SciTech Connect (OSTI)

    Tambo, T.; Falson, J. Kozuka, Y.; Maryenko, D.; Tsukazaki, A.; Kawasaki, M.

    2014-08-28

    The adaptation of air-gap dielectric based field-effect transistor technology to controlling the MgZnO/ZnO heterointerface confined two-dimensional electron system (2DES) is reported. We find it possible to tune the charge density of the 2DES via a gate electrode spatially separated from the heterostructure surface by a distance of 5??m. Under static gating, the observation of the quantum Hall effect suggests that the charge carrier density remains homogeneous, with the 2DES in the 3?mm square sample the sole conductor. The availability of this technology enables the exploration of the charge carrier density degree of freedom in the pristine sample limit.

  11. Mapping quadrupole collectivity in the Cd isotopes: The breakdown of

    Office of Scientific and Technical Information (OSTI)

    harmonic vibrational motion (Journal Article) | SciTech Connect Mapping quadrupole collectivity in the Cd isotopes: The breakdown of harmonic vibrational motion Citation Details In-Document Search Title: Mapping quadrupole collectivity in the Cd isotopes: The breakdown of harmonic vibrational motion The stable Cd isotopes have long been used as paradigms for spherical vibrational motion. Extensive investigations with in-beam {gamma} spectroscopy have resulted in very-well-established level

  12. CD-2, Approve Performance Baseline | Department of Energy

    Office of Environmental Management (EM)

    2, Approve Performance Baseline CD-2, Approve Performance Baseline CD-2, Approve Performance Baseline << Resource Center | CD-3 >> Description Completion of preliminary design is the first major milestone in the project Execution Phase. The design must be sufficiently mature (refer to DOE O 413.3B, Appendix C, Paragraph 4) at the time of CD-2 approval to provide reasonable assurance that the design will be implementable within the approved PB. The document signed by the CE or PME

  13. DOE CD-4 Review of the MINERvA Project

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    DOE CD-4 Review of the MINERvA Project Main INjector ExpeRiment v-A May 12, 2010 | Overview | CD-4 Documentation| Other Documents| Overview of Charge and Experiment MINERvA Overview (2.2 MB pdf) Review Agenda (all times EDT) (pdf) Review Charge (pdf) Review Presentation by MINERvA Project (DRAFT until the week of May 12) (docdb page) Required CD-4 Documentation CD-4 Document Checklist (pdf) Technical Requirements Completion Document (pdf) Quality Assurance Plan (pdf) Safety Documentation Hazard

  14. Electrodeposition of zinc on glassy carbon from ZnCl/sub 2/ and ZnBr/sub 2/ electrolytes

    SciTech Connect (OSTI)

    McBreen, J.; Gannon, E.

    1983-08-01

    The initial stages of the electrocrystallization of zinc from 3M ZnCl/sub 2/ and 3M ZnBr/sub 2/ on glassy carbon has been investigated using cyclic voltametry, the potential step method, and scanning electron microscopy. Particular care was taken to ensure electrolyte purity and to eliminate resistance effects in the measurements. The nucleation overvoltage in 3M ZnCl/sub 2/ was about 17 and about 12 mV in 3M ZnBr/sub 2/. In 3M ZnCl/sub 2/, the current transients from the potential step measurements could be fitted to a simple model that assumes instantaneous nucleation followed by growth of three dimensional centers under kinetic control. A similar mechanism is operative for 3M ZnBr/sub 2/ at low overvoltages. At higher overvoltages, the current transient is governed by mixed kinetic and diffusion control and cannot be fitted to a simple model. The lower nucleation overvoltage and the faster kinetics in 3M ZnBr/sub 2/ is correlated with the lower stability constants for the zinc bromide complexes. Erroneous results are obtained when resistance effects are not accounted for.

  15. Determination of the number density of excited and ground Zn atoms during rf magnetron sputtering of ZnO target

    SciTech Connect (OSTI)

    Maaloul, L.; Gangwar, R. K.; Stafford, L.

    2015-07-15

    A combination of optical absorption spectroscopy (OAS) and optical emission spectroscopy measurements was used to monitor the number density of Zn atoms in excited 4s4p ({sup 3}P{sub 2} and {sup 3}P{sub 0}) metastable states as well as in ground 4s{sup 2} ({sup 1}S{sub 0}) state in a 5 mTorr Ar radio-frequency (RF) magnetron sputtering plasma used for the deposition of ZnO-based thin films. OAS measurements revealed an increase by about one order of magnitude of Zn {sup 3}P{sub 2} and {sup 3}P{sub 0} metastable atoms by varying the self-bias voltage on the ZnO target from ?115 to ?300?V. Over the whole range of experimental conditions investigated, the triplet-to-singlet metastable density ratio was 5??1, which matches the statistical weight ratio of these states in Boltzmann equilibrium. Construction of a Boltzmann plot using all Zn I emission lines in the 200500?nm revealed a constant excitation temperature of 0.33??0.04?eV. In combination with measured populations of Zn {sup 3}P{sub 2} and {sup 3}P{sub 0} metastable atoms, this temperature was used to extrapolate the absolute number density of ground state Zn atoms. The results were found to be in excellent agreement with those obtained previously by actinometry on Zn atoms using Ar as the actinometer gas [L. Maaloul and L. Stafford, J. Vac. Sci. Technol., A 31, 061306 (2013)]. This set of data was then correlated to spectroscopic ellipsometry measurements of the deposition rate of Zn atoms on a Si substrate positioned at 12?cm away from the ZnO target. The deposition rate scaled linearly with the number density of Zn atoms. In sharp contrast with previous studies on RF magnetron sputtering of Cu targets, these findings indicate that metastable atoms play a negligible role on the plasma deposition dynamics of Zn-based coatings.

  16. The effects of fabrication temperature on current-voltage characteristics and energy efficiencies of quantum dot sensitized ZnOH-GO hybrid solar cells

    SciTech Connect (OSTI)

    Islam, S. M. Z.; Gayen, Taposh; Tint, Naing; Alfano, Robert; Shi, Lingyan; Seredych, Mykola; Bandosz, Teresa J.

    2014-11-07

    The effects of fabrication temperature are investigated on the performance of CdSe quantum dot (QD)-sensitized hybrid solar cells of the composite material of zinc (hydr)oxide (ZnOH-GO)with 2?wt.?% graphite oxide. The current-voltage (I-V) and photo-current measurements show that higher fabrication temperatures yield greater photovoltaic power conversion efficiencies that essentially indicate more efficient solar cells. Two Photon Fluorescence images show the effects of temperature on the internal morphologies of the solar devices based on such materials. The CdSe-QD sensitized ZnOH-GO hybrid solar cells fabricated at 450?C showing conversion of ?10.60% under a tungsten lamp (12.1 mW/cm{sup 2}) are reported here, while using potassium iodide as an electrolyte. The output photocurrent, I (?A) with input power, P (mW/cm{sup 2}) is found to be superlinear, showing a relation of I?=?P{sup n}, where n?=?1.4.

  17. Pressure-Induced Structural Transformations of ZnO Nanowires...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Pressure-Induced Structural Transformations of ZnO Nanowires Probed by X-ray Diffraction Citation Details In-Document Search Title: Pressure-Induced Structural ...

  18. Designing optical metamaterial with hyperbolic dispersion based on Al:ZnO/ZnO nano-layered structure using Atomic Layer Deposition technique

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kelly, Priscilla; Liu, Mingzhao; Kuznetsova, Lyuba

    2016-04-07

    In this study, nano-layered Al:ZnO/ZnO hyperbolic dispersion metamaterial with a large number of layers was fabricated using the atomic layer deposition (ALD) technique. Experimental dielectric functions for Al:ZnO/ZnO structures are obtained by an ellipsometry technique in the visible and near-infrared spectral ranges. The theoretical modeling of the Al:ZnO/ZnO dielectric permittivity is done using effective medium approximation. A method for analysis of spectroscopic ellipsometry data is demonstrated to extract the optical permittivity for this highly anisotropic nano-layered metamaterial. The results of the ellipsometry analysis show that Al:ZnO/ZnO structures with a 1:9 ALD cycle ratio exhibit hyperbolic dispersion transition change near 1.8more » μm wavelength.« less

  19. Strain-dependent photoluminescence behavior in three geometries of CdSe/CdS nanocrystals

    SciTech Connect (OSTI)

    Choi, Charina L; Koski, Kristie J; Sivasankar, Sanjeevi; Alivisatos, A Paul

    2009-05-26

    In recent years, a new generation of quantum confined colloidal semiconductor structures has emerged, with more complex shapes than simple quantum dots1, 2. These include nanorods3 and tetrapods4. Beyond shape, it is also now possible to spatially vary the electron and hole potentials within these nanoparticles by varying the composition. Examples of these new structures include seeded dots, rods, and tetrapods, which contain a CdSe core embedded within a CdS shell5, 6. These structures may have many uses beyond those envisioned for simple quantum dots, which are frequently employed in luminescent applications7. This paper is concerned with changes in the optoelectronic properties of tetrapods when the arms are bent. We demonstrate that seeded tetrapods can serve as an optical strain gauge, capable of measuring forces on the order of nanonewtons. We anticipate that a nanocrystal strain gauge with optical readout will be useful for applications ranging from sensitive optomechanical devices to biological force investigations.

  20. U.S. Team Green Building Challenge (CD-ROM)

    SciTech Connect (OSTI)

    Not Available

    2002-09-01

    Mini-CD with copies of U.S. Team materials handed out at the International Green Building Challenge conference in Oslo, Norway in September 2002. CD contents contains map of U.S., project brochures, project posters, and GBTool spreadsheets.

  1. Native defects in MBE-grown CdTe

    SciTech Connect (OSTI)

    Olender, Karolina; Wosinski, Tadeusz; Makosa, Andrzej; Tkaczyk, Zbigniew; Kolkovsky, Valery; Karczewski, Grzegorz

    2013-12-04

    Deep-level traps in both n- and p-type CdTe layers, grown by molecular-beam epitaxy on GaAs substrates, have been investigated by means of deep-level transient spectroscopy (DLTS). Four of the traps revealed in the DLTS spectra, which displayed exponential kinetics for capture of charge carriers into the trap states, have been assigned to native point defects: Cd interstitial, Cd vacancy, Te antisite defect and a complex formed of the Te antisite and Cd vacancy. Three further traps, displaying logarithmic capture kinetics, have been ascribed to electron states of treading dislocations generated at the mismatched interface with the substrate and propagated through the CdTe layer.

  2. High efficient ZnO nanowalnuts photocatalyst: A case study

    SciTech Connect (OSTI)

    Yan, Feng; Zhang, Siwen; Liu, Yang; Liu, Hongfeng; Qu, Fengyu; Cai, Xue; Wu, Xiang

    2014-11-15

    Highlights: Walnut-like ZnO nanostructures are synthesized through a facile hydrothermal method. Morphologies and microstructures of the as-obtained ZnO products were investigated. The photocatalytic results demonstrate that methyl orange (MO) aqueous solution can be degraded over 97% after 45 min under UV light irradiation. - Abstract: Walnut-like ZnO nanostructures are successfully synthesized through a facile hydrothermal method. The structure and morphology of the as-synthesized products were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The photocatalytic properties of ZnO nanowalnuts are investigated by photodegradating several organic dyes, such as Congo red (CR), methyl orange (MO) and eosin red aqueous solutions under UV irradiation, respectively. The results demonstrate that methyl orange (MO) aqueous solution can be degraded over 97% after 45 min under UV light irradiation. In addition, eosin red and Congo red (CR) aqueous solution degradation experiments are also conducted in the same condition, respectively. It showed that ZnO nanowalnuts represent high photocatalytic activities with a degradation efficiency of 87% for CR with 115 min of irradiation and 97% for eosin red with 55 min of irradiation. The reported ZnO products may be promising candidates as the photocatalysts in waste water treatment.

  3. The CD36, CLA-1(CD36L1), and LIMPII (CD36L2) gene family: Cellular distribution, chromosomal location, and genetic evolution

    SciTech Connect (OSTI)

    Calvo, D.; Vega, M.A.; Dopazo, J.

    1995-01-01

    CD36, CLA-1, and LIMPII are single polypeptide membrane glycoproteins, and the genes encoding them constitute a recently described gene family. In the present paper, a cDNA encoding the human lysosomal membrane protein LIMPII was used to determine its expression pattern in cells of various lineages. Like CLA-1, and in contrast with the restricted expression of CD36, the expression of LIMPII is widespread. Mapping of the human LIMPII and CLA-1 genes (gene symbols CD36L2 and CD36L1, respectively) to specific chromosomes revealed that CLA-1, LIMPII, and CD36 do not form a gene cluster, but are found dispersed on chromosomes 12, 4, and 7, respectively. These data, together with the phylogenetic analysis carried out for the members of this family, indicate that the LIMPII, CIA-1, and CD36 genes diverged early in evolution from an ancestor gene, possibly before the divergence between the arthropods and the vertebrates. 48 refs., 5 figs.

  4. Synthesis of reduced graphene oxide/ZnO nanorods composites on graphene coated PET flexible substrates

    SciTech Connect (OSTI)

    Huang, Lei, E-mail: leihuang@shnu.edu.cn; Guo, Guilue; Liu, Yang; Chang, Quanhong; Shi, Wangzhou

    2013-10-15

    Graphical abstract: - Highlights: ZnO nanorods synthesized on CVD-graphene and rGO surfaces, respectively. ZnO/CVD-graphene and ZnO/rGO form a distinctive porous 3D structure. rGO/ZnO nanostructures possibility in energy storage devices. - Abstract: In this work, reduced graphene oxide (rGO)/ZnO nanorods composites were synthesized on graphene coated PET flexible substrates. Both chemical vapor deposition (CVD) graphene and reduced graphene oxide (rGO) films were prepared following by hydrothermal growth of vertical aligned ZnO nanorods. Reduced graphene sheets were then spun coated on the ZnO materials to form a three dimensional (3D) porous nanostructure. The morphologies of the ZnO/CVD graphene and ZnO/rGO were investigated by SEM, which shows that the ZnO nanorods grown on rGO are larger in diameters and have lower density compared with those grown on CVD graphene substrate. As a result of fact, the rough surface of nano-scale ZnO on rGO film allows rGO droplets to seep into the large voids of ZnO nanorods, then to form the rGO/ZnO hierarchical structure. By comparison of the different results, we conclude that rGO/ZnO 3D nanostructure is more desirable for the application of energy storage devices.

  5. Effect of Morphology of CdS thin film on the Photocatalytic Decomposition of Hydrogen Sulfide

    SciTech Connect (OSTI)

    Takahashi, A.; Ishiyama, T.; Takahashi, H.; Sato, Y.; Jeyadevan, B.; Tohji, K.

    2007-03-20

    Photocatalytic activity of the CdS thin film depended very much on the film density, adhesion between the CdS and substrate, and whether effective electron path existed or not. We have proposed the formation of a bridging layer of Cd metal to improve the film density, adhesivity and the electron conduction path. Here, we report the results of the study undertaken to develop CdS/Cd (dendrite)/Ti film with enhanced photocatalytic property to decompose hydrogen sulphide. CdS/Cd (dendrite)/Ti photocatalyst showed the highest photocatalytic activity and photocurrent, which was 1.4 times higher than the traditional CdS/Ti photocatalyst.

  6. Pressure-dependent Optical Behaviors of Colloidal CdSe Nanoplatelets...

    Office of Scientific and Technical Information (OSTI)

    dependent Optical Behaviors of Colloidal CdSe Nanoplatelets Citation Details In-Document Search Title: Pressure-dependent Optical Behaviors of Colloidal CdSe Nanoplatelets Authors: ...

  7. Microsoft Word - MicroBooNE CD-2-3a appr.docx

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    23a Approve Performance Baseline and Approve Limited Construction of the Micro Booster ... Decision (CD) 2 "Approve Performance Baseline" and CD-3a "Approve Limited ...

  8. RG&E (Gas)- Residential Efficiency Program

    Broader source: Energy.gov [DOE]

    An online rebate reservation system is used to ensure program funds are not overextended. All new rebate requests must first be reserved in the rebate reservation system to be valid. The program...

  9. J rg Calefice | Open Energy Information

    Open Energy Info (EERE)

    it. Jrg Calefice is a company located in Germany . References " Jrg Calefice" Retrieved from "http:en.openei.orgwindex.php?titleJrgCalefice&oldid782975...

  10. Phase stability in the Cd-Mg system

    SciTech Connect (OSTI)

    Asta, M.; McCormack, R.; de Fontaine, D.

    1993-12-31

    This paper reports on results of a theoretical study of solid-state phase equilibria and short-range order in Cd-Mg alloys. Results of first-principles linear muffin-tin orbital method total-energy calculations for seven hcp-based superstructures have been combined with cluster-variation-method calculations of thermodynamic properties in order to compute the Cd-Mg phase diagram. Effect on the calculated phase diagram of contributions to the alloy free energy arising from atomic vibrations and structural relaxations are assessed using available experimental information for ordered and disordered alloys in the Cd-Mg system.

  11. Process Development for High Voc CdTe Solar Cells

    SciTech Connect (OSTI)

    Ferekides, C. S.; Morel, D. L.

    2011-05-01

    This is a cumulative and final report for Phases I, II and III of this NREL funded project (subcontract # XXL-5-44205-10). The main research activities of this project focused on the open-circuit voltage of the CdTe thin film solar cells. Although, thin film CdTe continues to be one of the leading materials for large-scale cost-effective production of photovoltaics, the efficiency of the CdTe solar cells have been stagnant for the last few years. This report describes and summarizes the results for this 3-year research project.

  12. 'Giant' multishell CdSe nanocrystal quantum dots with supporessed blinking: novel fluorescent probes for real-time detection of single-molecule events

    SciTech Connect (OSTI)

    Hollingsworth, Jennifer A; Vela, Javier; Htoon, Han; Klimov, Victor I; Casson, Amy R; Chen, Yongfen

    2009-01-01

    We reported for the first time that key nanocrystal quantum dot (NQD) optical properties-quantum yield, photobleaching and blinking-can be rendered independent ofNQD surface chemistry and environment by growth of a very thick, defect-free inorganic shell. Here, we show the precise shell-thickness dependence of these effects. We demonstrate that 'giant-shell' NQDs can be largely non-blinking for observation times as long as 54 minutes and lhat on-time fractions are independent of experimental time-resolution from 1-200 ms. These effects are primarily demonstrated on (CdSe)CdS (core)shell NQDs, but we also show that alloyed shells comprising Cd.Znl.'S and terminated with a non-cytotoxic ZnS layer exhibit similar properties. The mechanism for suppressed blinking and dramatically enhanced stability is attributed to both effective isolation of the NQD core excitonic wavefunction from the NQD surface, as well as a quasi-Type II electronic structure. The unusual electronic structure provides for effective spatial separation of the electron and hole into the shell and core, respectively, and, thereby, for reduced efficiencies in non-radiative Auger recombination.

  13. Synthesis, characterization and optical properties of hybrid PVAZnO nanocomposite: A composition dependent study

    SciTech Connect (OSTI)

    Hemalatha, K.S. [Department of Physics, Bangalore University, Bangalore 560 056, Karnataka (India); Department of Physics, Maharani's Science College for Women, Palace Road, Bangalore 560 001, Karnataka (India); Rukmani, K., E-mail: rukmani9909@yahoo.co.in [Department of Physics, Bangalore University, Bangalore 560 056, Karnataka (India); Suriyamurthy, N. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India); Nagabhushana, B.M. [Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore 560 054, Karnataka (India)

    2014-03-01

    Graphical abstract: - Highlights: ZnO nanoparticles were prepared by solution combustion method. PVAZnO nanocomposites were synthesized by solution casting method. Doped and undoped films were characterized using different techniques. Red shift in optical band gap was observed in Nanocomposite films with respect to nano ZnO. Photoluminescence intensity was found to be optimum for PVA10 mol% ZnO nanocomposite film. - Abstract: Nanocomposites of poly vinyl alcohol (PVA) and ZnO have been synthesized using the solution casting technique for different concentrations of nano ZnO powder prepared by low temperature solution combustion method. The formation of polymer nanocomposite and changes in the structural and micro structural properties of the materials were investigated by X-ray diffraction, Energy dispersive X ray spectroscopy and optical microscopy techniques (FTIR and UVVisible). The surface morphology of PVAZnO nanocomposite films were elucidated using Scanning Electron Microscopy. The optical absorption spectrum of nano ZnO shows blue shift in the optical band gap energy with respect to characteristic bulk ZnO at room temperature, whereas PVAZnO hybrid films show red shift with respect to nano ZnO. The photoluminescence studies show that the intensity of the blue emission (470 nm) varies with change in concentration of ZnO with an optimum intensity observed at 10 mol% of ZnO.

  14. Compensation of flare-induced CD changes EUVL

    DOE Patents [OSTI]

    Bjorkholm, John E. (Pleasanton, CA); Stearns, Daniel G. (Los Altos, CA); Gullikson, Eric M. (Oakland, CA); Tichenor, Daniel A. (Castro Valley, CA); Hector, Scott D. (Oakland, CA)

    2004-11-09

    A method for compensating for flare-induced critical dimensions (CD) changes in photolithography. Changes in the flare level results in undesirable CD changes. The method when used in extreme ultraviolet (EUV) lithography essentially eliminates the unwanted CD changes. The method is based on the recognition that the intrinsic level of flare for an EUV camera (the flare level for an isolated sub-resolution opaque dot in a bright field mask) is essentially constant over the image field. The method involves calculating the flare and its variation over the area of a patterned mask that will be imaged and then using mask biasing to largely eliminate the CD variations that the flare and its variations would otherwise cause. This method would be difficult to apply to optical or DUV lithography since the intrinsic flare for those lithographies is not constant over the image field.

  15. Optical Properties of CdSe Nanoparticle Assemblies

    SciTech Connect (OSTI)

    Huser, T; Gerion, D; Zaitseva, N; Krol, D M; Leon, F R

    2003-11-24

    We report on three-dimensional fluorescence imaging of micron-size faceted crystals precipitated from solutions of CdSe nanocrystals. Such crystals have previously been suggested to be superlattices of CdSe quantum dots [1,2]. Possible applications for these materials include their use in optical and optoelectronic devices. The micron-size crystals were grown by slow evaporation from toluene solutions of CdSe nanocrystals in the range of 3-6 nm, produced by traditional wet-chemistry techniques. By using a confocal microscope with laser illumination, three-dimensional raster-scanning and synchronized hyper-spectral detection, we have generated spatial profiles of the fluorescence emission intensity and spectrum. The fluorescence data of the micro-crystals were compared with spectra of individual nanocrystals obtained from the same solution. The results do not support the assertion that these microcrystals consist of CdSe superlattices.

  16. Substrate CdTe Efficiency Improvements - Energy Innovation Portal

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Substrate CdTe Efficiency Improvements National Renewable Energy Laboratory Contact NREL About This Technology Publications: PDF Document Publication 11-28PCT Application as-published (984 KB) Technology Marketing Summary Thin film solar cells have been the focus of many research facilities in recent years that are working to decrease manufacturing costs and increase cell efficiency. Cadmium telluride (CdTe) has been well recognized as a promising photovoltaic material for thin film solar cells

  17. Process for fabricating ZnO-based varistors

    DOE Patents [OSTI]

    Lauf, Robert J.

    1985-01-01

    The invention is a process for producing ZnO-based varistors incorporating a metal oxide dopant. In one form, the invention comprises providing a varistor powder mix of colloidal particles of ZnO and metal-oxide dopants including Bi.sub.2 O.sub.3. The mix is hot-pressed to form a compact at temperatures below 850.degree. C. and under conditions effecting reduction of the ZnO to sub-stoichiometric oxide. This promotes densification while restricting liquid formation and grain growth. The compact then is heated under conditions restoring the zinc oxide to stoichiometric composition, thus improving the varistor properties of the compact. The process produces fine-grain varistors characterized by a high actual breakdown voltage and a high average breakdown voltage per individual grain boundary.

  18. Nitrogen is a deep acceptor in ZnO

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tarun, M. C.; Iqbal, M. Zafar; McCluskey, M. D.

    2011-04-14

    Zinc oxide is a promising material for blue and UV solid-state lighting devices, among other applications. Nitrogen has been regarded as a potential p-type dopant for ZnO. However, recent calculations indicate that nitrogen is a deep acceptor. This paper presents experimental evidence that nitrogen is, in fact, a deep acceptor and therefore cannot produce p-type ZnO. A broad photoluminescence (PL) emission band near 1.7 eV, with an excitation onset of ~2.2 eV, was observed, in agreement with the deep-acceptor model of the nitrogen defect. Thus the deep-acceptor behavior can be explained by the low energy of the ZnO valence bandmore » relative to the vacuum level.« less

  19. Process for fabricating ZnO-based varistors

    DOE Patents [OSTI]

    Lauf, R.J.

    The invention is a process for producing ZnO-based varistors incorporating a metal oxide dopant. In one form, the invention comprises providing a varistor powder mix of colloidal particles of ZnO and metal-oxide dopants including Bi/sub 2/O/sub 3/. The mix is hot-pressed to form a compact at temperatures below 850/sup 0/C and under conditions effecting reduction of the ZnO to sub-stoichiometric oxide. This promotes densification while restricting liquid formation and grain growth. The compact then is heated under conditions restoring the zinc oxide to stoichiometric composition, thus improving the varistor properties of the compact. The process produces fine-grain varistors characterized by a high actual breakdown voltage and a high average breakdown voltage per individual grain boundary.

  20. High mobility ZnO nanowires for terahertz detection applications

    SciTech Connect (OSTI)

    Liu, Huiqiang; Peng, Rufang E-mail: chusheng@mail.sysu.edu.cn; Chu, Shijin; Chu, Sheng E-mail: chusheng@mail.sysu.edu.cn

    2014-07-28

    An oxide nanowire material was utilized for terahertz detection purpose. High quality ZnO nanowires were synthesized and field-effect transistors were fabricated. Electrical transport measurements demonstrated the nanowire with good transfer characteristics and fairly high electron mobility. It is shown that ZnO nanowires can be used as building blocks for the realization of terahertz detectors based on a one-dimensional plasmon detection configuration. Clear terahertz wave (∼0.3 THz) induced photovoltages were obtained at room temperature with varying incidence intensities. Further analysis showed that the terahertz photoresponse is closely related to the high electron mobility of the ZnO nanowire sample, which suggests that oxide nanoelectronics may find useful terahertz applications.

  1. Enhanced photoelectrochemical responses of ZnO films through Ga and N codoping

    SciTech Connect (OSTI)

    Ahn, Kwang-Soon; Yan, Yanfa; Shet, Sudhakar; Deutsch, Todd; Turner, John; Al-Jassim, Mowafak

    2007-12-03

    We report on the crystallinity and photoelectrochemical (PEC) response of ZnO thin films codoped by Ga and N. The ZnO:(Ga,N) thin films were deposited by cosputtering at room temperature and followed by postannealing at 500 deg. C in air for 2 h. We found that ZnO:(Ga,N) thin films exhibited significantly enhanced crystallinity compared to ZnO doped solely with N at the same growth conditions. Furthermore, ZnO:(Ga,N) thin films exhibited enhanced N incorporation over ZnO doped solely with N at high temperatures. As a result, ZnO:(Ga,N) thin films achieved dramatically improved PEC response, compared to ZnO thin films doped solely with N at any conditions. Our results suggest a general way to improve PEC response for wide-band-gap oxides.

  2. Alignment nature of ZnO nanowires grown on polished and nanoscale...

    Office of Scientific and Technical Information (OSTI)

    Alignment nature of ZnO nanowires grown on polished and nanoscale etched lithium niobate ... Citation Details In-Document Search Title: Alignment nature of ZnO nanowires grown on ...

  3. Band alignment and interfacial structure of ZnO/Si heterojunction...

    Office of Scientific and Technical Information (OSTI)

    of ZnOSi heterojunction with Alsub 2Osub 3 and HfOsub 2 as interlayers Citation Details In-Document Search Title: Band alignment and interfacial structure of ZnOSi ...

  4. One-step electrochemical synthesis of a grapheneZnO hybrid for improved photocatalytic activity

    SciTech Connect (OSTI)

    Wei, Ang; Xiong, Li; Sun, Li; Liu, Yanjun; Li, Weiwei; Lai, Wenyong; Liu, Xiangmei; Wang, Lianhui; Huang, Wei; Dong, Xiaochen

    2013-08-01

    Graphical abstract: - Highlights: GrapheneZnO hybrid was synthesized by one-step electrochemical deposition. GrapheneZnO hybrid presents a special structure and wide UVvis absorption spectra. GrapheneZnO hybrid exhibits an exceptionally higher photocatalytic activity for the degradation of dye methylene blue. - Abstract: A grapheneZnO (G-ZnO) hybrid was synthesized by one-step electrochemical deposition. During the formation of ZnO nanostructure by cathodic electrochemical deposition, the graphene oxide was electrochemically reduced to graphene simultaneously. Scanning electron microscope images, X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectra, and UVvis absorption spectra indicate the resulting G-ZnO hybrid presents a special structure and wide UVvis absorption spectra. More importantly, it exhibits an exceptionally higher photocatalytic activity for the degradation of dye methylene blue than that of pure ZnO nanostructure under both ultraviolet and sunlight irradiation.

  5. Yb-Zn-Al ternary system: CaCu{sub 5}-type derived compounds in...

    Office of Scientific and Technical Information (OSTI)

    Yb-Zn-Al ternary system: CaCusub 5-type derived compounds in the zinc-rich corner Citation Details In-Document Search Title: Yb-Zn-Al ternary system: CaCusub 5-type derived ...

  6. Structure of graphene oxide dispersed with ZnO nanoparticles

    SciTech Connect (OSTI)

    Yadav, Rishikesh Pandey, Devendra K.; Khare, P. S.

    2014-10-15

    Graphene has been proposed as a promising two-dimensional nanomaterial with outstanding electronic, optical, thermal and mechanical properties for many applications. In present work a process of dispersion of graphene oxide with ZnO nanoparticles in ethanol solution with different pH values, have been studied. Samples have been characterized by XRD, SEM, PL, UV-visible spectroscopy and particles size measurement. The results analysis indicates overall improved emission spectrum. It has been observed that the average diameter of RGO (Reduced Graphene Oxide) decreases in presence of ZnO nanoparticles from 3.8?m to 0.41?m.

  7. Effect of ZnO seed layer on the morphology and optical properties of ZnO nanorods grown on GaN buffer layers

    SciTech Connect (OSTI)

    Nandi, R. Mohan, S. Major, S. S.; Srinivasa, R. S.

    2014-04-24

    ZnO nanorods were grown by chemical bath deposition on sputtered, polycrystalline GaN buffer layers with and without ZnO seed layer. Scanning electron microscopy and X-ray diffraction show that the ZnO nanorods on GaN buffer layers are not vertically well aligned. Photoluminescence spectrum of ZnO nanorods grown on GaN buffer layer, however exhibits a much stronger near-band-edge emission and negligible defect emission, compared to the nanorods grown on ZnO buffer layer. These features are attributed to gallium incorporation at the ZnO-GaN interface. The introduction of a thin (25 nm) ZnO seed layer on GaN buffer layer significantly improves the morphology and vertical alignment of ZnO-NRs without sacrificing the high optical quality of ZnO nanorods on GaN buffer layer. The presence of a thick (200 nm) ZnO seed layer completely masks the effect of the underlying GaN buffer layer on the morphology and optical properties of nanorods.

  8. Properties of electrospun CdS and CdSe filled poly(methyl methacrylate) (PMMA) nanofibres

    SciTech Connect (OSTI)

    Mthethwa, T.P.; Moloto, M.J.; De Vries, A.; Matabola, K.P.

    2011-04-15

    Graphical abstract: SEM images of CdS/PMMA showing coiling as loading of CdS nanoparticles is increased. Thermal stability is increased with increase in %loading of both CdS and CdSe nanoparticles. Research highlights: {yields} TOPO-capped CdS and HDA-capped CdSe nanoparticles were synthesized and fully characterized. {yields} The nanoparticles were mixed with the polymer, PMMA using electrospinning technique using 2, 5 and 10% weight loadings. {yields} The mixture was spun to produce fibres with optical and thermal properties showing significant change and also the increase in loading causing bending or spiraling. {yields} Both TEM images for nanoparticles and SEM for fibres shows the morphology and sizes of the particles. -- Abstract: Electrospinning technique was used to fabricate poly(methyl methacrylate) (PMMA) fibres incorporating CdS and CdSe quantum dots (nanoparticles). Different nanoparticle loadings (2, 5 and 10 wt% with respect to PMMA) were used and the effect of the quantum dots on the properties of the fibres was studied. The optical properties of the hybrid composite fibres were investigated by photoluminescence and UV-vis spectrophotometry. Scanning electron microscopy (SEM), X-ray diffraction and FTIR spectrophotometry were also used to investigate the morphology and structure of the fibres. The optical studies showed that the size-tunable optical properties can be achieved in the polymer fibres by addition of quantum dots. SEM images showed that the morphologies of the fibres were dependent on the added amounts of quantum dots. A spiral type of morphology was observed with an increase in the concentration of CdS and CdSe nanoparticles. Less beaded structures and bigger diameter fibres were obtained at higher quantum dot concentrations. X-ray diffractometry detected the amorphous peaks of the polymer and even after the quantum dots were added and the FTIR analysis shows that there was no considerable interaction between the quantum dots and the polymer fibres at low concentration of quantum dots however at higher concentrations some interactions were observed which shows that QDs were present on the surfaces of the fibres.

  9. Photoinduced reduction of surface states in Fe:ZnO

    SciTech Connect (OSTI)

    Knut, R. Palmgren, P.; Karis, O.; Lagerqvist, U.; Pohl, A.; Pal, P.; Svedlindh, P.

    2015-05-28

    We report on the electronic structure of nano-crystalline Fe:ZnO, which has recently been found to be an efficient photocatalyst. Using resonant photoemission spectroscopy, we determine the binding energy of Fe 3d states corresponding to different valencies and coordination of the Fe atoms. The photo-activity of ZnO reduces Fe from 3+ to 2+ in the surface region of the nano-crystalline material due to the formation of oxygen vacancies. Electronic states corresponding to low-spin Fe{sup 2+} are observed and attributed to crystal field modification at the surface. These states are potentially important for the photocatalytic sensitivity to visible light due to their location deep in the ZnO bandgap. X-ray absorption and x-ray photoemission spectroscopy suggest that Fe is only homogeneously distributed for concentrations up to 3%. Increased concentrations does not result in a higher concentration of Fe ions in the surface region. This is limiting the photocatalytic functionality of ZnO, where the most efficient Fe doping concentration has been shown to be 1%-4%.

  10. Phosphatidylinositol 4,5-Bisphosphate Clusters the Cell Adhesion Molecule CD44 and Assembles a Specific CD44-Ezrin Heterocomplex, as Revealed by Small Angle Neutron Scattering

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khajeh, Jahan Ali; Ju, Jeong Ho; Gupta, Yogesh K.; Stanley, Christopher B.; Do, Changwoo; Heller, William T.; Aggarwal, Aneel K.; Callaway, David J.E.; Bu, Zimei

    2015-01-08

    The cell adhesion molecule CD44 regulates diverse cellular functions, including cell-cell and cell-matrix interaction, cell motility, migration, differentiation, and growth. In cells, CD44 co-localizes with the membrane-cytoskeleton adapter protein Ezrin, which links the CD44 assembled receptor signaling complexes to the cytoskeletal actin and organizes the spatial and temporal localization of signaling events. Here we report that the cytoplasmic tail of CD44 (CD44ct) is largely disordered and adopts an autoinhibited conformation, which prevents CD44ct from binding directly to activated Ezrin in solution. Binding to the signaling lipid phosphatidylinositol 4,5-biphosphlate (PIP2) disrupts autoinhibition in CD44ct, and activates CD44ct to associate with Ezrin.more » Further, using contrast variation small angle neutron scattering, we show that PIP2 mediates the assembly of a specific hetero-tetramer complex of CD44ct with Ezrin. This study reveals a novel autoregulation mechanism in the cytoplasmic tail of CD44 and the role of PIP2 in mediating the assembly of multimeric CD44ct-Ezrin complexes. We hypothesize that polyvalent electrostatic interactions are responsible for the assembly of multimeric PIP2-CD44-Ezrin complexes.« less

  11. Defect Chemistry Study of Nitrogen Doped ZnO Thin Films

    SciTech Connect (OSTI)

    Miami University: Dr. Lei L. Kerr Wright State University: Dr. David C. Look and Dr. Zhaoqiang Fang

    2009-11-29

    Our team has investigated the defect chemistry of ZnO:N and developed a thermal evaporation (vapor-phase) method to synthesis p-type ZnO:N. Enhanced p-type conductivity of nitrogen doped ZnO via nano/micro structured rods and Zn-rich Co-doping process were studied. Also, an extended X-Ray absorption fine structure study of p-type nitrogen doped ZnO was conducted. Also reported are Hall-effect, photoluminescence, and DLTS studies.

  12. Resorption Rate Tunable Bioceramic: Si, Zn-Modified Tricalcium Phosphate

    SciTech Connect (OSTI)

    Xiang Wei

    2006-08-09

    This dissertation is organized in an alternate format. Several manuscripts which have already been published or are to be submitted for publication have been included as separate chapters. Chapter 1 is a general introduction which describes the dissertation organization and introduces the human bone and ceramic materials as bone substitute. Chapter 2 is the background and literature review on dissolution behavior of calcium phosphate, and discussion of motivation for this research. Chapter 3 is a manuscript entitled ''Si,Zn-modified tricalcium phosphate: a phase composition and crystal structure study'', which was published in ''Key Engineering Materials'' [1]. Chapter 4 gives more crystal structure details by neutron powder diffraction, which identifies the position for Si and Zn substitution and explains the stabilization mechanism of the structure. A manuscript entitled ''Crystal structure analysis of Si, Zn-modified Tricalcium phosphate by Neutron Powder Diffraction'' will be submitted to Biomaterials [2]. Chapter 5 is a manuscript, entitled ''Dissolution behavior and cytotoxicity test of Si, Zn-modified tricalcium phosphate'', which is to be submitted to Biomaterials [3]. This paper discusses the additives effect on the dissolution behavior of TCP, and cytotoxicity test result is also included. Chapter 6 is the study of hydrolysis process of {alpha}-tricalcium phosphate in the simulated body fluid, and the phase development during drying process is discussed. A manuscript entitled ''Hydrolysis of {alpha}-tricalcium phosphate in simulated body fluid and phase transformation during drying process'' is to be submitted to Biomaterials [4]. Ozan Ugurlu is included as co-authors in these two papers due to his TEM contributions. Appendix A is the general introduction of the materials synthesis, crystal structure and preliminary dissolution result. A manuscript entitled ''Resorption rate tunable bioceramic: Si and Zn-modified tricalcium phosphate'' was published in Ceramic Engineering and Science Proceedings (the 29th International Conference on Advanced Ceramics and Composites - Advances in Bioceramics and Biocomposites) [5].

  13. Theoretical study of syngas hydrogenation to methanol on the polar Zn-terminated ZnO(0001) surface

    SciTech Connect (OSTI)

    Zhao, Ya-Fan; Rousseau, Roger J.; Li, Jun; Mei, Donghai

    2012-08-02

    Methanol synthesis from syngas (CO/CO2/H2) hydrogenation on the perfect Znterminated polar ZnO(0001) surface have been investigated using periodic density functional theory calculations. Our results show that direct CO2 hydrogenation to methanol on the perfect ZnO(0001) surface is unlikely because in the presence of surface atomic H and O the highly stable formate (HCOO) and carbonate (CO3) readily produced from CO2 with low barriers 0.11 and 0.09 eV will eventually accumulate and block the active sites of the ZnO(0001) surface. In contrast, methanol synthesis from CO hydrogenation is thermodynamically and kinetically feasible on the perfect ZnO(0001) surface. CO can be consecutively hydrogenated into formyl (HCO), formaldehyde (H2CO), methoxy (H3CO) intermediates, leading to the final formation of methanol (H3COH). The reaction route via hydroxymethyl (H2COH) intermediate, a previously proposed species on the defected Oterminated ZnO( ) surface, is kinetically inhibited on the perfect ZnO(0001) surface. The rate-determining step in the consecutive CO hydrogenation route is the hydrogenation of H3CO to H3COH. We also note that this last hydrogenation step is pronouncedly facilitated in the presence of water by lowering the activation barrier from 1.02 to 0.55 eV. This work was supported by the U.S. Department of Energy Office of Basic Energy Sciences, Division of Chemical Sciences, Biosciences and Geosciences, and performed at EMSL, a national scientific user facility sponsored by the Department of Energys Office of Biological and Environmental Research located at Pacific Northwest National Laboratory (PNNL). Computational resources were provided at EMSL and the National Energy Research Scientific Computing Center at Lawrence Berkeley National Laboratory. J. Li and Y.-F. Zhao were also financially supported by the National Natural Science Foundation of China (Nos. 20933003 and 91026003) and the National Basic Research Program of China (No. 2011CB932400). Y.-F. Zhao acknowledges the fellowship from PNNL.

  14. Local structures of polar wurtzites Zn1-xMgxO studied by raman and 67Zn/25Mg NMR spectroscopies and by total neutron scattering

    SciTech Connect (OSTI)

    Proffen, Thomas E; Kim, Yiung- Il; Cadars, Sylvian; Shayib, Ramzy; Feigerle, Charles S; Chmelka, Bradley F; Seshadri, Ram

    2008-01-01

    Research in the area of polar semiconductor heterostructures has been growing rapidly, driven in large part by interest in two-dimensional electron gas (2DEG) systems. 2DEGs are known to form at heterojunction interfaces that bear polarization gradients. They can display extremely high electron mobilities, especially at low temperatures, owing to spatial confinement of carrier motions. Recent reports of 2DEG behaviors in Ga{sub 1-x}Al{sub x}N/GaN and Zn{sub 1-x}Mg{sub x}O/ZnO heterostructures have great significance for the development of quantum Hall devices and novel high-electron-mobility transistors (HEMTs). 2DEG structures are usually designed by interfacing a polar semiconductor with its less or more polar alloys in an epitaxial manner. Since the quality of the 2DEG depends critically on interface perfection, as well as the polarization gradient at the heterojunction, understanding compositional and structural details of the parent and alloy semiconductors is an important component in 2DEG design and fabrication. Zn{sub 1-x}Mg{sub x}O/ZnO is one of the most promising heterostructure types for studies of 2DEGs, due to the large polarization of ZnO, the relatively small lattice mismatch, and the large conduction band offsets in the Zn{sub 1-x}Mg{sub x}O/ZnO heterointerface. Although 2DEG formation in Zn{sub 1-x}Mg{sub x}O/ZnO heterostructures have been researched for some time, a clear understanding of the alloy structure of Zn{sub 1-x}Mg{sub x}O is currently lacking. Here, we conduct a detailed and more precise study of the local structure of Zn{sub 1-x}Mg{sub x}O alloys using Raman and solid-state nuclear magnetic resonance (NMR), in conjunction with neutron diffraction techniques.

  15. Seeded Growth of Highly Luminescent CdSe/CdS Nano-Heterostructures with Rod and Tetrapod Morphologies

    SciTech Connect (OSTI)

    Talapin, Dmitri; Talapin, Dmitri V.; Nelson, James H.; Shevchenko, Elena V.; Aloni, Shaul; Sadtler, Bryce; Alivisatos, A. Paul

    2007-08-09

    We have demonstrated that seeded growth of nanocrystals offers a convenient way to design nanoheterostructures with complex shapes and morphologies by changing the crystalline structure of the seed. By using Use nanocrystals with wurtzite and zinc blende structure as seeds for growth of US nanorods, we synthesized CdSe/CdS heterostructure nanorods and nanotetrapods, respectively. Both of these structures showed excellent luminescentproperties, combining high photoluminescence efficiency (similar to 80 and similar to 50percent for nanorods and nanotetrapods, correspondingly), giant extinction coefficients (similar to 2 x 10(7) and similar to 1.5 x 10(8) M-1 cm (-1) at 350 nm for nanorods and nanotetrapods, correspondingly), and efficient energy transfer from the US arms into the emitting CdSe Core.

  16. Growth, steady-state, and time-resolved photoluminescence study of CdTe/MgCdTe double heterostructures on InSb substrates using molecular beam epitaxy

    SciTech Connect (OSTI)

    DiNezza, Michael J.; Liu, Shi; Kirk, Alexander P.; Zhang, Yong-Hang; School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287 ; Zhao, Xin-Hao; School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287

    2013-11-04

    CdTe/MgCdTe double heterostructures (DHs) are grown on InSb substrates using molecular beam epitaxy and reveal strong photoluminescence with over double the intensity of a GaAs/AlGaAs DH with an identical layer structure design grown on GaAs. Time-resolved photoluminescence of the CdTe/MgCdTe DH gives a Shockley-Read-Hall recombination lifetime of 86 ns, which is more than one order of magnitude longer than that of typical polycrystalline CdTe films. These findings indicate that monocrystalline CdTe/MgCdTe DHs effectively reduce surface recombination, have limited nonradiative interface recombination, and are promising for solar cells that could reach power conversion efficiencies similar to that of GaAs.

  17. Strain-Dependent Photoluminescence Behavior of CdSe/CdS Nanocrystals with Spherical, Linear, and Branched Topologies

    SciTech Connect (OSTI)

    Choi, Charina L.; Koski, Kristie J.; Sivasankar, Sanjeevi; Alivisatos, A. Paul

    2009-08-13

    The photoluminescence of CdSe/CdS core/shell quantum dots, nanorods, and tetrapods is investigated as a function of applied hydrostatic and non-hydrostatic pressure. The optoelectronic properties of all three nanocrystal morphologies are affected by strain. Furthermore, it is demonstrated that the unique morphology of a tetrapod is highly sensitive to non-isotropic stress environments. Seeded tetrapods can thereby serve as an optical strain gauge, capable of measuring forces on the order of nanonewtons. We anticipate that a nanocrystal strain gauge with optical readout will be useful for applications ranging from sensitive optomechanical devices to investigations of biomechanical processes.

  18. Growth of Single- and Bilayer ZnO on Au(111) and Interaction with Copper

    SciTech Connect (OSTI)

    Deng, Xingyi; Yao, Kun; Sun, Keju; Li, Wei-Xue; Lee, Junseok; Matranga, Christopher

    2013-05-30

    The stoichiometric single- and bi-layer ZnO(0001) have been prepared by reactive deposition of Zn on Au(111) and studied in detail with X-ray photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory calculations. Both single- and bi-layer ZnO(0001) adopt a planar, graphite-like structure similar to freestanding ZnO(0001) due to the weak van der Waals interactions dominating their adhesion with the Au(111) substrate. At higher temperature, the single-layer ZnO(0001) converts gradually to bi-layer ZnO(0001) due to the twice stronger interaction between two ZnO layers than the interfacial adhesion of ZnO with Au substrate. It is found that Cu atoms on the surface of bi-layer ZnO(0001) are mobile with a diffusion barrier of 0.31 eV, and likely to agglomerate and form nanosized particles at low coverages; while Cu atoms tend to penetrate a single layer of ZnO(0001) with a barrier of 0.10 eV, resulting in a Cu free surface.

  19. Improving the ethanol gas-sensing properties of porous ZnO microspheres by Co doping

    SciTech Connect (OSTI)

    Xiao, Qi Wang, Tao

    2013-08-01

    Graphical abstract: - Highlights: • Co-doped porous ZnO microspheres were synthesized. • 3 mol% Co-doped ZnO sensor showed the highest response to ethanol. • 3 mol% Co-doped ZnO sensor exhibited fast recovery property. • 3 mol% Co-doped ZnO sensor exhibited good selectivity and long-term stability. - Abstract: Porous Co-doped ZnO microspheres were prepared by a simple hydrothermal method combined with post-annealing. Co species existed as a form of divalent state in the sample and substituted Zn{sup 2+} sites in ZnO crystal lattice, which was affirmed by X-ray diffraction, UV–vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The gas-sensing measurements demonstrated that the 3 mol% Co-doped ZnO sample showed the highest response value to 100 ppm ethanol at 350 °C, which were 5 folds higher than that of the pure ZnO sample. In addition, the 3 mol% Co-doped ZnO sensor exhibited fast recovery property, good quantitative determination, good selectivity and long-term stability. The superior sensing properties were contributed to high specific surface area combined with the large amount of oxygen vacancies originating from Co doping.

  20. Molecular dynamics simulation of annealed ZnO surfaces

    SciTech Connect (OSTI)

    Min, Tjun Kit; Yoon, Tiem Leong; Lim, Thong Leng

    2015-04-24

    The effect of thermally annealing a slab of wurtzite ZnO, terminated by two surfaces, (0001) (which is oxygen-terminated) and (0001{sup ¯}) (which is Zn-terminated), is investigated via molecular dynamics simulation by using reactive force field (ReaxFF). We found that upon heating beyond a threshold temperature of ∼700 K, surface oxygen atoms begin to sublimate from the (0001) surface. The ratio of oxygen leaving the surface at a given temperature increases as the heating temperature increases. A range of phenomena occurring at the atomic level on the (0001) surface has also been explored, such as formation of oxygen dimers on the surface and evolution of partial charge distribution in the slab during the annealing process. It was found that the partial charge distribution as a function of the depth from the surface undergoes a qualitative change when the annealing temperature is above the threshold temperature.

  1. Initial results of the CD-1 reliable multicast experiment

    SciTech Connect (OSTI)

    Agarwal, D.; Stead, R.; Coan, B.; Burns, J. E.; Shah, N.; Kyriakopoulos, N.

    2000-09-29

    During the past year, an experiment has been underway to test use of reliable multicast capabilities for transmission of continuous data in the Global Communication Infrastructure. For the experiment a version of the CD-1 protocol was multicast enabled. The experiment has demonstrated the feasibility of transmitting data in a multicast mode over the GCI. In the case of the Comprehensive Nuclear Test-Ban Treaty the sender could be the station and the receivers the International Data Center (IDC) and one or more National Data Centers (NDC). The potential advantages of multicasting include (a) the timely receipt of the data by the IDC and the host NDC and (b) the simultaneous availability of the raw station data at, at least, two locations. The latter, by introducing redundant data paths, decreases the probability of loss of station data due to a potential failure of a single data receiver. This experiment is only one element of a needed more thorough assessment of the reliability and cost-effectiveness of introducing redundancies in the data transmission paths and the data sinks of the IMS. The next stage of the multicast experiment planned is installation of the multicast-enabled CD-1 software at the GERES IMS station, at the German NDC and at the IDC for further experiments with actual IMS station data. This stage of the experiment is waiting on installation of a GCI link to the German NDC. Negotiations regarding price for this installation have been on going between the Global Communication Infrastructure (GCI) contractor and the German NDC with no resolution. Current development of the CD-x protocol is proceeding in two complementary directions. Along with the work on a multicast enabled version of CD-1 there is also work to develop CD-1.1, which will add end-to-end reliability to the CD-1 protocol among other things. A possible future activity would be to combine the reliable multicast and the end-to-end reliability mechanisms into one CD-x protocol version.

  2. Field emission properties of ZnO nanosheet arrays

    SciTech Connect (OSTI)

    Naik, Kusha Kumar; Rout, Chandra Sekhar E-mail: dj.late@ncl.res.in E-mail: csrout@iitbbs.ac.in; Khare, Ruchita; More, Mahendra A.; Chakravarty, Disha; Late, Dattatray J. E-mail: dj.late@ncl.res.in E-mail: csrout@iitbbs.ac.in; Thapa, Ranjit E-mail: dj.late@ncl.res.in E-mail: csrout@iitbbs.ac.in

    2014-12-08

    Electron emission properties of electrodeposited ZnO nanosheet arrays grown on Indium tin oxide coated glass substrates have been studied. Influence of oxygen vacancies on electronic structures and field emission properties of ZnO nanosheets are investigated using density functional theory. The oxygen vacancies produce unshared d electrons which form an impurity energy state; this causes shifting of Fermi level towards the vacuum, and so the barrier energy for electron extraction reduces. The ZnO nanosheet arrays exhibit a low turn-on field of 2.4 V/μm at 0.1 μA/cm{sup 2} and current density of 50.1 μA/cm{sup 2} at an applied field of 6.4 V/μm with field enhancement factor, β = 5812 and good field emission current stability. The nanosheet arrays grown by a facile electrodeposition process have great potential as robust high performance vertical structure electron emitters for future flat panel displays and vacuum electronic device applications.

  3. Coulomb Excitation of the N = 50 nucleus {sup 80}Zn

    SciTech Connect (OSTI)

    Van de Walle, J.; Cocolios, T. E.; Huyse, M.; Ivanov, O.; Mayet, P.; Raabe, R.; Sawicka, M.; Stefanescu, I.; Duppen, P. van; Aksouh, F.; Behrens, T.; Gernhauser, R.; Kroell, T.; Kruecken, R.; Bildstein, V.; Blazhev, A.; Eberth, J.

    2008-05-12

    Neutron rich Zinc isotopes, including the N = 50 nucleus {sup 80}Zn, were produced and post-accelerated at the Radioactive Ion Beam (RIB) facility REX-ISOLDE (CERN). Low-energy Coulomb excitation was induced on these isotopes after post-acceleration, yielding B(E2) strengths to the first excited 2{sup +} states. For the first time, an excited state in {sup 80}Zn was observed and the 2{sub 1}{sup +} state in {sup 78}Zn was established. The measured B(E2,2{sub 1}{sup +}{yields}0{sub 1}{sup +}) values are compared to two sets of large scale shell model calculations. Both calculations reproduce the observed B(E2) systematics for the full Zinc isotopic chain. The results for N = 50 isotones indicate a good N = 50 shell closure and a strong Z = 28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus {sup 78}Ni.

  4. Enhanced photocatalytic performance of Ga{sup 3+}-doped ZnO

    SciTech Connect (OSTI)

    Zhong, Jun Bo; Li, Jian Zhang; Zeng, Jun; He, Xi Yang; Hu, Wei; Shen, Yue Cheng

    2012-11-15

    Graphical abstract: In general, the strong SPS response corresponds to the high separation rate of photoinduced charge carriers on the basis of the SPS principle. The photovoltage of Ga{sup 3+}-doped ZnO is higher than that of ZnO, thus it can be confirmed that the Ga{sup 3+}-doped ZnO has a higher charge separation rate than the ZnO sample. Among these samples, 1%Ga has highest charge separation rate. Display Omitted Highlights: ► Ga{sup 3+} has been employed to dope ZnO photocatalyst. ► Ga{sup 3+} increases the BET surface area and changes the morphology of ZnO. ► The photoinduced charge separation rate has been enhanced. ► The photocatalytic activity has been greatly promoted. -- Abstract: ZnO and Ga{sup 3+}-doped ZnO with different molar ratio of Ga/Zn (1%, 2% and 3%) were prepared by a parallel flow precipitation method. The photocatalysts prepared were characterized by BET surface area, X-ray diffraction (XRD), UV/vis diffuse reflectance spectroscopy (DRS), scanning electron microscope (SEM) and surface photovoltage spectroscopy (SPS), respectively. The results show that doping Ga{sup 3+} into ZnO increases the BET surface area. The XRD spectra of the photocatalysts calcined at 573 K show only the characteristic peaks of wurtzite-type. Ga{sup 3+}-doped ZnO absorbs much more light than ZnO in the visible light region. Doping Ga{sup 3+} into ZnO greatly changes the morphology of ZnO and enhances the photoinduced charge separation rate. The photocatalytic activity of ZnO and Ga{sup 3+}-doped ZnO for decolorization of methyl orange (MO) solution was evaluated, of all the photocatalysts prepared, the Ga{sup 3+}-doped ZnO with 1% possesses the best photocatalytic activity and the possible reason was discussed.

  5. The effects of high temperature processing on the structural and optical properties of oxygenated CdS window layers in CdTe solar cells

    SciTech Connect (OSTI)

    Paudel, Naba R.; Grice, Corey R.; Xiao, Chuanxiao; Yan, Yanfa

    2014-07-28

    High efficiency CdTe solar cells typically use oxygenated CdS (CdS:O) window layers. We synthesize CdS:O window layers at room temperature (RT) and 270 °C using reactive sputtering. The band gaps of CdS:O layers deposited at RT increase when O{sub 2}/(O{sub 2} + Ar) ratios in the deposition chamber increase. On the other hand, the band gaps of CdS:O layers deposited at 270 °C decrease as the O{sub 2}/(O{sub 2} + Ar) ratios increase. Interestingly, however, our high temperature closed-space sublimation (CSS) processed CdTe solar cells using CdS:O window layers deposited at RT and 270 °C exhibit very similar cell performance, including similar short-circuit current densities. To understand the underlying reasons, CdS:O thin films deposited at RT and 270 °C are annealed at temperatures that simulate the CSS process of CdTe deposition. X-ray diffraction, atomic force microscopy, and UV-visible light absorption spectroscopy characterization of the annealed films reveals that the CdS:O films deposited at RT undergo grain regrowth and/or crystallization and exhibit reduced band gaps after the annealing. Our results suggest that CdS:O thin films deposited at RT and 270 °C should exhibit similar optical properties after the deposition of CdTe layers, explaining the similar cell performance.

  6. T-685: Cisco Warranty CD May Load Malware From a Remote Site...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    5: Cisco Warranty CD May Load Malware From a Remote Site T-685: Cisco Warranty CD May Load Malware From a Remote Site August 5, 2011 - 3:26pm Addthis PROBLEM: A vulnerability was...

  7. McMullen Valley Water C&D Dist | Open Energy Information

    Open Energy Info (EERE)

    McMullen Valley Water C&D Dist Jump to: navigation, search Name: McMullen Valley Water C&D Dist Place: Arizona Phone Number: 99-928-859-3647 Website: www.harcuvarco.com Outage...

  8. CdTe Thin Film Solar Cells and Modules Tutorial; NREL (National Renewable Energy Laboratory)

    SciTech Connect (OSTI)

    Albin, David S.

    2015-06-13

    This is a tutorial presented at the 42nd IEEE Photovoltaics Specialists Conference to cover the introduction, background, and updates on CdTe cell and module technology, including CdTe cell and module structure and fabrication.

  9. Super-Poissonian Statistics of Photon Emission from Single CdSe...

    Office of Scientific and Technical Information (OSTI)

    Statistics of Photon Emission from Single CdSe-CdS Core-Shell Nanocrystals Coupled to Metal Nanostructures Citation Details In-Document Search Title: Super-Poissonian Statistics of ...

  10. Pressure-induced Phase Transition in Thiol-capped CdTe Nanoparticles

    SciTech Connect (OSTI)

    Wu, F; Zaug, J; Young, C; Zhang, J Z

    2006-11-29

    Phase transitions for CdTe nanoparticles (NPs) under high pressure up to 37.0 GPa have been studied using fluorescence measurements. The phase transition from cinnarbar to rocksalt phase has been observed in CdTe NPs solution at 5.8 GPa, which is much higher than the phase transition pressure of bulk CdTe (3.8 GPa) and that of CdTe NPs in solid form (0.8 GPa). CdTe NPs solution therefore shows elevated phase transition pressure and enhanced stability against pressure compared with bulk CdTe and CdTe NPs in solid forms. The enhanced stability of CdTe NPs solution has been attributed to possible shape change in the phase transition and/or inhomogeneous strains in nanoparticle solutions.

  11. C-340 Complex D&D Final Lessons Learned (Post CD-4), Environmental...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    C-340 Complex D&D Final Lessons Learned (Post CD-4), Environmental Management Cleanup, Sep 2011 C-340 Complex D&D Final Lessons Learned (Post CD-4), Environmental Management ...

  12. Fabrication and Physics of CdTe Devices by Sputtering: Final Report, 1 March 2005 - 30 November 2008

    SciTech Connect (OSTI)

    Compaan, A.; Collins, R.; Karpov, V.; Giolando, D.

    2009-04-01

    Work to understand CdS/CdTe solar cell device physics; increase magnetron sputtering rate (while keeping high device quality); reduce thickness of CdTe layers (while keeping voltage and fill factor).

  13. Impact of strain on electronic defects in (Mg,Zn)O thin films

    SciTech Connect (OSTI)

    Schmidt, Florian Mller, Stefan; Wenckstern, Holger von; Benndorf, Gabriele; Pickenhain, Rainer; Grundmann, Marius

    2014-09-14

    We have investigated the impact of strain on the incorporation and the properties of extended and point defects in (Mg,Zn)O thin films by means of photoluminescence, X-ray diffraction, deep-level transient spectroscopy (DLTS), and deep-level optical spectroscopy. The recombination line Y?, previously detected in ZnO thin films grown on an Al-doped ZnO buffer layer and attributed to tensile strain, was exclusively found in (Mg,Zn)O samples being under tensile strain and is absent in relaxed or compressively strained thin films. Furthermore a structural defect E3 can be detected via DLTS measurements and is only incorporated in tensile strained samples. Finally it is shown that the omnipresent deep-level E3 in ZnO can only be optically recharged in relaxed ZnO samples.

  14. Phases in the Al-Yb-Zn system between 25 and 50 at% ytterbium (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect SciTech Connect Search Results Journal Article: Phases in the Al-Yb-Zn system between 25 and 50 at% ytterbium Citation Details In-Document Search Title: Phases in the Al-Yb-Zn system between 25 and 50 at% ytterbium Phases YbZn{sub 1-x}Al{sub x}, YbZn{sub 2-x}Al{sub x} and YbZn{sub 3-x}Al{sub x} were studied by electron microprobe analysis and X-ray single crystal and powder methods. The compound YbZn{sub 0.8}Al{sub 0.2} crystallizes with the CsCl-type, a=3.635(2)

  15. CD-1, Approve Alternative Selection and Cost Range | Department of Energy

    Office of Environmental Management (EM)

    1, Approve Alternative Selection and Cost Range CD-1, Approve Alternative Selection and Cost Range CD-1, Approve Alternative Selection and Cost Range << Resource Center | CD-2 >> DescriptionCD-1 approval marks the completion of the project definition phase and the conceptual design. This is an iterative process to define, analyze, and refine project concepts and alternatives. This process uses a systems engineering methodology that integrates requirements analysis, risk

  16. Critical Decision 0 (CD-0) ESAAB and PMRC Brief Template | Department of

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Energy 0 (CD-0) ESAAB and PMRC Brief Template Critical Decision 0 (CD-0) ESAAB and PMRC Brief Template Template for briefing Critical Decisions to the ESAAB and/or PMRC July 2015 File Template Key Resources PMCDP EVMS PARS IIe FPD Resource Center PM Newsletter Forms and Templates More Documents & Publications DOE Project Management Risk Committee (PMRC) SOP Critical Decision 1 (CD-1) ESAAB and PMRC Brief Template Critical Decision 2 (CD-2

  17. Critical Decision 1 (CD-1) ESAAB and PMRC Brief Template | Department of

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Energy 1 (CD-1) ESAAB and PMRC Brief Template Critical Decision 1 (CD-1) ESAAB and PMRC Brief Template Template for briefing Critical Decisions to the ESAAB and/or PMRC July 2015 File Template Key Resources PMCDP EVMS PARS IIe FPD Resource Center PM Newsletter Forms and Templates More Documents & Publications Critical Decision 3 (CD-3) ESAAB and PMRC Brief Template DOE Project Management Risk Committee (PMRC) SOP Critical Decision 0 (CD-0

  18. Critical Decision 3 (CD-3) ESAAB and PMRC Brief Template | Department of

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Energy 3 (CD-3) ESAAB and PMRC Brief Template Critical Decision 3 (CD-3) ESAAB and PMRC Brief Template Template for briefing Critical Decisions to the ESAAB and/or PMRC July 2015 File Template Key Resources PMCDP EVMS PARS IIe FPD Resource Center PM Newsletter Forms and Templates More Documents & Publications Critical Decision 1 (CD-1) ESAAB and PMRC Brief Template Critical Decision 0 (CD-0) ESAAB and PMRC Brief Template DOE Project Management Risk Committee (PMRC) SOP

  19. Enhancement of photoluminescence properties in ZnO/AlN bilayer

    Office of Scientific and Technical Information (OSTI)

    heterostructures grown by atomic layer deposition (Journal Article) | SciTech Connect Enhancement of photoluminescence properties in ZnO/AlN bilayer heterostructures grown by atomic layer deposition Citation Details In-Document Search Title: Enhancement of photoluminescence properties in ZnO/AlN bilayer heterostructures grown by atomic layer deposition The AlN/ZnO bilayer heterostructures were deposited on Si (100) substrate by thermal atomic layer deposition. X-ray diffraction results show

  20. Magnetism in undoped ZnS studied from density functional theory

    SciTech Connect (OSTI)

    Xiao, Wen-Zhi E-mail: llwang@hun.edu.cn; Rong, Qing-Yan; Xiao, Gang; Wang, Ling-ling E-mail: llwang@hun.edu.cn; Meng, Bo

    2014-06-07

    The magnetic property induced by the native defects in ZnS bulk, thin film, and quantum dots are investigated comprehensively based on density functional theory within the generalized gradient approximation + Hubbard U (GGA?+?U) approach. We find the origin of magnetism is closely related to the introduction of hole into ZnS systems. The relative localization of S-3p orbitals is another key to resulting in unpaired p-electron, due to Hund's rule. For almost all the ZnS systems under study, the magnetic moment arises from the S-dangling bonds generated by Zn vacancies. The charge-neutral Zn vacancy, Zn vacancy in 1? charge sate, and S vacancy in the 1+ charge sate produce a local magnetic moment of 2.0, 1.0, and 1.0??{sub B}, respectively. The Zn vacancy in the neutral and 1? charge sates are the important cause for the ferromagnetism in ZnS bulk, with a Curie temperature (T{sub C}) above room temperature. For ZnS thin film with clean (111) surfaces, the spins on each surface are ferromagnetically coupled but antiferromagnetically coupled between two surfaces, which is attributable to the internal electric field between the two polar (111) surfaces of the thin film. Only surface Zn vacancies can yield local magnetic moment for ZnS thin film and quantum dot, which is ascribed to the surface effect. Interactions between magnetic moments on S-3p states induced by hole-doping are responsible for the ferromagnetism observed experimentally in various ZnS samples.

  1. Alignment nature of ZnO nanowires grown on polished and nanoscale etched

    Office of Scientific and Technical Information (OSTI)

    lithium niobate surface through self-seeding thermal evaporation method (Journal Article) | SciTech Connect Alignment nature of ZnO nanowires grown on polished and nanoscale etched lithium niobate surface through self-seeding thermal evaporation method Citation Details In-Document Search Title: Alignment nature of ZnO nanowires grown on polished and nanoscale etched lithium niobate surface through self-seeding thermal evaporation method Highlights: * ZnO nanowires were grown directly on

  2. Preface: Thin Solid Films Topical Special Issue on ZnO Related Transparent

    Office of Scientific and Technical Information (OSTI)

    Conductive Oxides (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Preface: Thin Solid Films Topical Special Issue on ZnO Related Transparent Conductive Oxides Citation Details In-Document Search Title: Preface: Thin Solid Films Topical Special Issue on ZnO Related Transparent Conductive Oxides World-wide research activities on ZnO and related transparent conductive oxides (TCO) in thin film, nanostructured, and multilayered forms are driven by the vast

  3. Cross-Sectional Conductive Atomic Force Microscopy of CdTe/CdS Solar Cells: Effects of Etching and Back-Contact Processes; Preprint

    SciTech Connect (OSTI)

    Moutinho, H. R.; Dhere, R. G.; Jiang, C.-S.; Gessert, T. A.; Duda, A. M.; Young, M.; Metzger, W. K.; Li, X.; Al-Jassim, M. M.

    2006-05-01

    We investigated the effects of the etching processes using bromine and nitric-phosphoric acid solutions, as well as of Cu, in the bulk electrical conductivity of CdTe/CdS solar cells using conductive atomic force microscopy (C-AFM). Although the etching process can create a conductive layer on the surface of the CdTe, the layer is very shallow. In contrast, the addition of a thin layer of Cu to the surface creates a conductive layer inside the CdTe that is not uniform in depth, is concentrated at grains boundaries, and may short circuit the device if the CdTe is too thin. The etching process facilitates the Cu diffusion and results in thicker conductive layers. The existence of this inhomogeneous conductive layer directly affects the current transport and is probably the reason for needing thick CdTe in these devices.

  4. III-nitrides on oxygen- and zinc-face ZnO substrates (Journal Article) |

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect SciTech Connect Search Results Journal Article: III-nitrides on oxygen- and zinc-face ZnO substrates Citation Details In-Document Search Title: III-nitrides on oxygen- and zinc-face ZnO substrates The characteristics of III-nitrides grown on zinc- and oxygen-face ZnO by plasma-assisted molecular beam epitaxy were investigated. The reflection high-energy electron diffraction pattern indicates formation of a cubic phase at the interface between III-nitride and both Zn- and

  5. Defects in paramagnetic Co-doped ZnO films studied by transmission electron microscopy

    SciTech Connect (OSTI)

    Kovacs, Andras; Ney, A.; Duchamp, Martial; Ney, V.; Boothroyd, Chris; Galindo, Pedro L.; Kaspar, Tiffany C.; Chambers, Scott A.; Dunin-Borkowski, Rafal

    2013-12-23

    We have studied planar defects in epitaxial Co:ZnO dilute magnetic semiconductor thin films deposited on c-plane sapphire (Al2O3) and the Co:ZnO/Al2O3 interface structure at atomic resolution using aberration-corrected transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS). Comparing Co:ZnO samples deposited by pulsed laser deposition and reactive magnetron sputtering, both exhibit extrinsic stacking faults, incoherent interface structures, and compositional variations within the first 3-4 Co:ZnO layers at the interface.. In addition, we have measured the local strain which reveals the lattice distortion around the stacking faults.

  6. Organic Molecule Functionalized Zn3P2 Nanowire Inorganic-Organic...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Organic Molecule Functionalized Zn3P2 Nanowire Inorganic-Organic Hybrid Thermoelectrics Demonstrates self-catalytic schemes for large-scale synthesis of compound semiconductor ...

  7. Optical and morphological properties of graphene sheets decorated with ZnO nanowires via polyol enhancement

    SciTech Connect (OSTI)

    Sharma, Vinay, E-mail: winn201@gmail.com; Rajaura, Rajveer Singh, E-mail: winn201@gmail.com [Centre for Converging Technologies, University of Rajasthan, Jaipur - 302004 (India); Sharma, Preetam K.; Srivastava, Subodh; Vijay, Y. K. [Department of Physics, Thin Film and Membrane Science Lab., University of Rajasthan, Jaipur - 302004 (India); Sharma, S. S. [Department of Physics, Govt. Women Engineering College, Ajmer- 305002 (India)

    2014-04-24

    Graphene-ZnO nanocomposites have proven to be very useful materials for photovoltaic and sensor applications. Here, we report a facile, one-step in situ polymerization method for synthesis of graphene sheets randomly decorated with zinc oxide nanowires using ethylene glycol as solvent. We have used hydrothermal treatment for growth of ZnO nanowires. UV-visible spectra peak shifting around 288nm and 307 nm shows the presence of ZnO on graphene structure. Photoluminiscence spectra (PL) in 400nm-500nm region exhibits the luminescence quenching effect. Scanning electron microscopy (SEM) image confirms the growth of ZnO nanowires on graphene sheets.

  8. Visible light photocatalytic property of Zn doped V{sub 2}O{sub 5} nanoparticles

    SciTech Connect (OSTI)

    Suresh, R.; Giribabu, K.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

    2012-06-05

    The Zn doped V{sub 2}O{sub 5} nanoparticles were synthesized by thermal decomposition method. The prepared samples were characterized by various techniques like Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) studies, UV-Visible spectroscopy (UV-Vis) and field emission scanning electron microscopy (FE-SEM). The photocatalytic activities of pure and Zn doped V{sub 2}O{sub 5} nanoparticles were examined based on the photodegradation of Rhodamine B (RhB). Experimental results indicated that the Zn doped V{sub 2}O{sub 5} photocatalyst (the molar ratio of V to Zn is 99: 1) exhibited maximum photocatalytic activity.

  9. Nonlinear optical characterization of ZnS thin film synthesized by chemical spray pyrolysis method

    SciTech Connect (OSTI)

    G, Sreeja V; Anila, E. I. R, Reshmi John, Manu Punnan; V, Sabitha P; Radhakrishnan, P.

    2014-10-15

    ZnS thin film was prepared by Chemical Spray Pyrolysis (CSP) method. The sample was characterized by X-ray diffraction method and Z scan technique. XRD pattern showed that ZnS thin film has hexagonal structure with an average size of about 5.6nm. The nonlinear optical properties of ZnS thin film was studied by open aperture Z-Scan technique using Q-switched Nd-Yag Laser at 532nm. The Z-scan plot showed that the investigated ZnS thin film has saturable absorption behavior. The nonlinear absorption coefficient and saturation intensity were also estimated.

  10. Green synthesis of graphene nanosheets/ZnO composites and electrochemical properties

    SciTech Connect (OSTI)

    Wang Jun; Gao Zan; Li Zhanshuang; Wang Bin; Yan Yanxia; Liu Qi; Mann, Tom; Zhang Milin; Jiang Zhaohua

    2011-06-15

    A green and facile approach was demonstrated to prepare graphene nanosheets/ZnO (GNS/ZnO) composites for supercapacitor materials. Glucose, as a reducing agent, and exfoliated graphite oxide (GO), as precursor, were used to synthesize GNS, then ZnO directly grew onto conducting graphene nanosheets as electrode materials. The small ZnO particles successfully anchored onto graphene sheets as spacers to keep the neighboring sheets separate. The electrochemical performances of these electrodes were analyzed by cyclic voltammetry, electrochemical impedance spectrometry and chronopotentiometry. Results showed that the GNS/ZnO composites displayed superior capacitive performance with large capacitance (62.2 F/g), excellent cyclic performance, and maximum power density (8.1 kW/kg) as compared with pure graphene electrodes. Our investigation highlight the importance of anchoring of small ZnO particles on graphene sheets for maximum utilization of electrochemically active ZnO and graphene for energy storage application in supercapacitors. - Graphical abstract: Glucose was used to synthesize GNS, then ZnO directly grew onto conducting graphene nanosheets as electrode materials for supercapacitor. Results showed that the composites have superior capacitive performance. Highlights: > Graphene nanosheets were synthesized via using glucose as a reducing agent. > The reductant and the oxidized product are environmentally friendly. > ZnO grew onto conducting graphene sheets keeping neighboring sheets separate. > The structure improves the contact between the electrode and the electrolyte. > Results showed that these composites have good electrochemical property.

  11. Structural Studies of Al:ZnO Powders and Thin Films | Stanford Synchrotron

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Radiation Lightsource Structural Studies of Al:ZnO Powders and Thin Films Monday, June 18, 2012 - 2:00pm SSRL Main Conference Room 137-322 Dr. Bridget Ingham, Associate Investigator, MacDiarmid Institute for Advanced Materials & Nanotechnology Al-doped ZnO (Al:ZnO) is a promising transparent conducting oxide. We have used complementary synchrotron and laboratory techniques to study the incorporation of Al within the ZnO lattice, and measure its effect on the crystallinity of thin films

  12. Metallic filament formation by aligned oxygen vacancies in ZnO-based resistive switches

    SciTech Connect (OSTI)

    Gu, Tingkun

    2014-05-28

    The electronic structure of ZnO with defects of oxygen vacancies were investigated by using first-principles methods. Some structure models were constructed in order to investigate the effects of the distribution of oxygen vacancies on the electronic properties of ZnO. By analyzing the calculated results, we found that only the aligned oxygen vacancies can form the conducting channel in ZnO, and the transformation of the oxygen vacancy from charged state to neutral state is consistent with the energetics rule of the forming aligned oxygen vacancies. As for the heterojunction of Pt/ZnO/Pt, the oxygen vacancies near the interface of Pt/ZnO depress the local Schottky barrier effectively, and the aligned oxygen vacancies in ZnO form a conducting filament connecting two Pt electrodes. The metallic filament formation in Pt/ZnO/Pt resistive switching cells should be closely related to the carrier injection from Pt electrode into ZnO and the arrangement of oxygen vacancies in ZnO slab.

  13. Synthesis and characterization of ZnO and Ni doped ZnO nanorods by thermal decomposition method for spintronics application

    SciTech Connect (OSTI)

    Saravanan, R.; Santhi, Kalavathy; Sivakumar, N.; Narayanan, V.; Stephen, A.

    2012-05-15

    Zinc oxide nanorods and diluted magnetic semiconducting Ni doped ZnO nanorods were prepared by thermal decomposition method. This method is simple and cost effective. The decomposition temperature of acetate and formation of oxide were determined by TGA before the actual synthesis process. The X-ray diffraction result indicates the single phase hexagonal structure of zinc oxide. The transmission electron microscopy and scanning electron microscopy images show rod like structure of ZnO and Ni doped ZnO samples with the diameter {approx} 35 nm and the length in few micrometers. The surface analysis was performed using X-ray photoelectron spectroscopic studies. The Ni doped ZnO exhibits room temperature ferromagnetism. This diluted magnetic semiconducting Ni doped ZnO nanorods finds its application in spintronics. - Highlights: Black-Right-Pointing-Pointer The method used is very simple and cost effective compared to all other methods for the preparation DMS materials. Black-Right-Pointing-Pointer ZnO and Ni doped ZnO nanorods Black-Right-Pointing-Pointer Ferromagnetism at room temperature.

  14. Manufacturing Process Optimization to Improve Stability, Yield and Efficiency of CdS/CdTe PV Devices: Final Report, December 2004 - January 2009

    SciTech Connect (OSTI)

    Sampath, W. S.; Enzenroth, A.; Barth, K.

    2009-03-01

    The research by Colorado State University advances the understanding of device stability, efficiency, and process yield for CdTe PV devices.

  15. Hazardous waste site characterization (on cd-rom). Data file

    SciTech Connect (OSTI)

    1996-07-01

    Site characterization is one facet of hazardous waste site investigations. Environmental scientists and engineers within and outside the regulated community are becoming overwhelmed by the increasing number of guidance manuals, directives, documents and software products relating to the characterization of hazardous waste sites. People in the private sector, academia, and government are looking for convenient, definitive sources for this information. This CD-ROM combines into a single source a collection of useful references. The CD-ROM contains over 3,200 pages of EPA`s RCRA and Superfund Directives and Manuals that may be searched by key words or printed. It also contains a compilation of EPA-developed computer programs and documents to aid environmental professionals in the characterization of hazardous waste sites.

  16. Deformation potentials of CdSe quantum dots

    SciTech Connect (OSTI)

    Li, Jingbo; Wang, Lin-Wang

    2004-06-02

    The size dependent deformation potentials of CdSe quantum dots are studied by first principle and semi-empirical pseudopotentials calculations. They find that the amplitude of the quantum dot deformation potential is only slightly larger than the bulk value, and this increase is mostly caused by the off {Lambda} point deformation potentials in the bulk, which are larger in amplitude than the {Lambda} point deformation potential.

  17. Modulation of Rhamm (CD168) for selective adipose tissue development

    DOE Patents [OSTI]

    Turley, Eva A; Bissell, Mina J

    2014-05-06

    Herein is described the methods and compositions for modulation of Rhamm, also known as CD 186, and its effects on wound repair, muscle differentiation, bone density and adipogeneisis through its ability to regulate mesenchymal stem cell differentiation. Compositions and methods are provided for blocking Rhamm function for selectively increasing subcutaneous, but not, visceral fat. Compositions and methods for modulating Rhamm in wound repair are also described.

  18. Ectopic expression of anti-HIV-1 shRNAs protects CD8{sup +} T cells

    Office of Scientific and Technical Information (OSTI)

    modified with CD4ζ CAR from HIV-1 infection and alleviates impairment of cell proliferation (Journal Article) | SciTech Connect Ectopic expression of anti-HIV-1 shRNAs protects CD8{sup +} T cells modified with CD4ζ CAR from HIV-1 infection and alleviates impairment of cell proliferation Citation Details In-Document Search Title: Ectopic expression of anti-HIV-1 shRNAs protects CD8{sup +} T cells modified with CD4ζ CAR from HIV-1 infection and alleviates impairment of cell proliferation

  19. Environmental awareness -- An interactive multimedia CD-ROM

    SciTech Connect (OSTI)

    Huntelmann, A.; Petruk, M.W.

    1998-07-01

    As corporations move to new and innovative ways of structuring high-performance work teams, effective training is being recognized as a key to insuring success. Time and scheduling constraints tend to limit the effectiveness of traditional approaches to training. This has led Edmonton Power Inc. to explore the use of CD-ROM based multimedia as a means of delivering individualized instruction in an effective and timely manner. This session will demonstrate a multimedia CD-ROM based course on Environmental Awareness designed for workers in the electrical utilities industry. The objective of the course is to make workers aware of their roles and responsibilities with respect to their impact on the environment. This session will also describe the instructional design strategy underlying this approach to training and will present some preliminary findings with respect to the effectiveness of this approach. Individuals who are interested in improving the effectiveness of their environmental training program as well as individuals who are interested in understanding the strengths of multimedia CD-ROM based training will find this session useful and informative.

  20. Controlled fabrication and tunable photoluminescence properties of Mn{sup 2+} doped grapheneZnO composite

    SciTech Connect (OSTI)

    Luan, Xinglong; Zhang, Yihe Tong, Wangshu; Shang, Jiwu; An, Qi; Huang, Hongwei

    2014-11-15

    Highlights: GrapheneZnO composites were synthesized by a mixed solvothermal method. ZnO quantum dots are distributed uniformly on the graphene sheets. A possible hypothesis is raised for the influence of graphene oxide on the nucleation of ZnO. Mn{sup 2+} doped grapheneZnO composites were fabricated and the emission spectra can be tuned by doping. - Abstract: GrapheneZnO composites (GZnO) with controlled morphology and photoluminescence property were synthesized by a mixed solvothermal method. Mixed solvent were composed by dimethyl sulfoxide and ethylene glycol. Fourier transform infrared spectroscopy, transmission electron microscopy and photoluminescence spectra were used to characterize GZnO. Graphene as a substrate can help the distribution and the dispersity of ZnO, and a possible model of the interaction between graphene oxide and ZnO particles is proposed. At the same time, graphene also reduce the size of ZnO particles to about 5 nm. Furthermore, Mn{sup 2+} ions dopes GZnO successfully by the mixed solvothermal synthesis and the doping of Mn{sup 2+} makes GZnO shift red from 465 nm to 548 nm and 554 nm in the emission spectrum. The changes of the emission spectrum by the adding of Mn{sup 2+} make GZnO have tunable photoluminescence spectrum which is desirable for practical applications.

  1. Structural Stability and Defect Energetics of ZnO from Diffusion Quantum Monte Carlo

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Santana Palacio, Juan A; Krogel, Jaron T; Kim, Jeongnim; Kent, Paul R; Reboredo, Fernando A

    2015-01-01

    We have applied the many-body ab-initio diffusion quantum Monte Carlo (DMC) method to study Zn and ZnO crystals under pressure, and the energetics of the oxygen vacancy, zinc interstitial and hydrogen impurities in ZnO. We show that DMC is an accurate and practical method that can be used to characterize multiple properties of materials that are challenging for density functional theory approximations. DMC agrees with experimental measurements to within 0.3 eV, including the band-gap of ZnO, the ionization potential of O and Zn, and the atomization energy of O2, ZnO dimer, and wurtzite ZnO. DMC predicts the oxygen vacancy asmore » a deep donor with a formation energy of 5.0(2) eV under O-rich conditions and thermodynamic transition levels located between 1.8 and 2.5 eV from the valence band maximum. Our DMC results indicate that the concentration of zinc interstitial and hydrogen impurities in ZnO should be low under n-type, and Zn- and H-rich conditions because these defects have formation energies above 1.4 eV under these conditions. Comparison of DMC and hybrid functionals shows that these DFT approximations can be parameterized to yield a general correct qualitative description of ZnO. However, the formation energy of defects in ZnO evaluated with DMC and hybrid functionals can differ by more than 0.5 eV.« less

  2. Cadmium sulfate and CdTe-quantum dots alter DNA repair in zebrafish (Danio rerio) liver cells

    SciTech Connect (OSTI)

    Tang, Song; Cai, Qingsong; Chibli, Hicham; Allagadda, Vinay; Nadeau, Jay L.; Mayer, Gregory D.

    2013-10-15

    Increasing use of quantum dots (QDs) makes it necessary to evaluate their toxicological impacts on aquatic organisms, since their contamination of surface water is inevitable. This study compares the genotoxic effects of ionic Cd versus CdTe nanocrystals in zebrafish hepatocytes. After 24 h of CdSO{sub 4} or CdTe QD exposure, zebrafish liver (ZFL) cells showed a decreased number of viable cells, an accumulation of Cd, an increased formation of reactive oxygen species (ROS), and an induction of DNA strand breaks. Measured levels of stress defense and DNA repair genes were elevated in both cases. However, removal of bulky DNA adducts by nucleotide excision repair (NER) was inhibited with CdSO{sub 4} but not with CdTe QDs. The adverse effects caused by acute exposure of CdTe QDs might be mediated through differing mechanisms than those resulting from ionic cadmium toxicity, and studying the effects of metallic components may be not enough to explain QD toxicities in aquatic organisms. - Highlights: Both CdSO{sub 4} and CdTe QDs lead to cell death and Cd accumulation. Both CdSO{sub 4} and CdTe QDs induce cellular ROS generation and DNA strand breaks. Both CdSO{sub 4} and CdTe QDs induce the expressions of stress defense and DNA repair genes. NER repair capacity was inhibited with CdSO{sub 4} but not with CdTe QDs.

  3. Structural Phase Transition in AuZn Alloys

    SciTech Connect (OSTI)

    Winn,B.L.; Shapiro, S.M.; Lashley, J.C.; Opeil, C.; Ratcliff, W.

    2009-05-03

    AuxZn1-x alloys undergo a shape memory martensitic transformation whose temperature and nature (continuous or discontinuous) is strongly composition dependent. Neutron diffraction experiments were performed on single crystals of x=50 and 52 to explore the structural changes occurring at the transition temperature. A transverse modulation with wavevector q0=(1/3,1/3,0) develops below the transition temperature, with no observable change in lattice parameter. However, the Bragg peak width shows a broadening suggesting an unresolved rhombohedral distortion similar to what has been observed in NiTi-Fe alloys.

  4. Fine structure on the green band in ZnO

    SciTech Connect (OSTI)

    Reynolds, D. C.; Look, D. C.; Jogai, B.

    2001-06-01

    An emission band at 2.4 eV, called the green band, is observed in most ZnO samples, no matter what growth technique is used. Sometimes this band includes fine structure, which consists mainly of doublets, repeated with a longitudinal-optical-phonon-energy spacing (72 meV). We have developed a vibronic model for the green band, based on transitions from two separate shallow donors to a deep acceptor. The donors, at energies 30 and 60 meV from the conduction-band edge, respectively, are also found from Hall-effect measurements. {copyright} 2001 American Institute of Physics.

  5. Synthesis, structural and optical characterization of undoped, N-doped ZnO and co-doped ZnO thin films

    SciTech Connect (OSTI)

    Pathak, Trilok Kumar Kumar, R.; Purohit, L. P.

    2015-05-15

    ZnO, N-doped ZnO and Al-N co-doped ZnO thin films were deposited on ITO coated corning glass by spin coater using sol-gel method. The films were annealed in air at 450°C for one hour. The crystallographic structure and morphology of the films were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The X-ray diffraction results confirm that the thin films are of wurtzite hexagonal with a very small distortion. The optical properties were investigated by transmission spectra of different films using spectrophotometer (Shimadzu UV-VIS-NIR 3600). The results indicate that the N doped ZnO thin films have obviously enhanced transmittance in visible region. Moreover, the thickness of the films has strong influences on the optical constants.

  6. Mechanical and Electrical Performance of Thermally Stable Au-ZnO films

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Schoeppner, Rachel L.; Goeke, Ronald S.; Moody, Neville R.; Bahr, David F.

    2015-03-28

    The mechanical properties, thermal stability, and electrical performance of Au–ZnO composite thin films are determined in this work. The co-deposition of ZnO with Au via physical vapor deposition leads to grain refinement over that of pure Au; the addition of 0.1 vol.% ZnO reduces the as-grown grain size by over 30%. The hardness of the as-grown films doubles with 2% ZnO, from 1.8 to 3.6 GPa as measured by nanoindentation. Films with ZnO additions greater than 0.5% show no significant grain growth after annealing at 350 °C, while pure gold and smaller additions do exhibit grain growth and subsequent mechanicalmore » softening. Films with 1% and 2% ZnO show a decrease of approximately 50% in electrical resistivity and no change in hardness after annealing. A model accounting for both changes in the interface structure between dispersed ZnO particles and the Au matrix captures the changes in mechanical and electrical resistivity. Furthermore, the addition of 1–2% ZnO co-deposited with Au provides a method to create mechanically hard and thermally stable films with a resistivity less than 80 nΩ-m. Our results complement previous studies of other alloying systems, suggesting oxide dispersion strengthened (ODS) gold shows a desirable hardness–resistivity relationship that is relatively independent of the particular ODS chemistry.« less

  7. Mechanical and Electrical Performance of Thermally Stable Au-ZnO films

    SciTech Connect (OSTI)

    Schoeppner, Rachel L.; Goeke, Ronald S.; Moody, Neville R.; Bahr, David F.

    2015-03-28

    The mechanical properties, thermal stability, and electrical performance of AuZnO composite thin films are determined in this work. The co-deposition of ZnO with Au via physical vapor deposition leads to grain refinement over that of pure Au; the addition of 0.1 vol.% ZnO reduces the as-grown grain size by over 30%. The hardness of the as-grown films doubles with 2% ZnO, from 1.8 to 3.6 GPa as measured by nanoindentation. Films with ZnO additions greater than 0.5% show no significant grain growth after annealing at 350 C, while pure gold and smaller additions do exhibit grain growth and subsequent mechanical softening. Films with 1% and 2% ZnO show a decrease of approximately 50% in electrical resistivity and no change in hardness after annealing. A model accounting for both changes in the interface structure between dispersed ZnO particles and the Au matrix captures the changes in mechanical and electrical resistivity. Furthermore, the addition of 12% ZnO co-deposited with Au provides a method to create mechanically hard and thermally stable films with a resistivity less than 80 n?-m. Our results complement previous studies of other alloying systems, suggesting oxide dispersion strengthened (ODS) gold shows a desirable hardnessresistivity relationship that is relatively independent of the particular ODS chemistry.

  8. Hierarchical Ag/ZnO micro/nanostructure: Green synthesis and enhanced photocatalytic performance

    SciTech Connect (OSTI)

    Gao, Shuyan; Jia, Xiaoxia; Yang, Shuxia; Li, Zhengdao; Jiang, Kai

    2011-04-15

    Ag/ZnO metal-semiconductor nanocomposites with hierarchical micro/nanostructure have been prepared by the hydrothermal synthesis in the presence of bovine serum albumin (BSA). The results suggest that this biomolecule-assisted hydrothermal method is an efficient route for the fabrication of Ag/ZnO nanocomposites by using BSA both a shape controller and a reducing agent of Ag{sup +} ions. Moreover, Ag nanoparticles on the ZnO act as electron sinks, improving the separation of photogenerated electrons and holes, increasing the surface hydroxyl contents of ZnO, facilitating trapping the photoinduced electrons and holes to form more active hydroxyl radicals, and thus, enhancing the photocatalytic efficiency of ZnO. This is a good example for the organic combination of green chemistry and functional materials. -- Graphical Abstract: A green strategy is report to construct Ag/ZnO metal-semiconductor nanocomposites with hierarchical micro/nanostructure and enhanced photocatalytic activity. Display Omitted Research highlights: > Hierarchical micro/nanostructured Ag/ZnO nanocomposites have been prepared via a green route. > Ag nanoparticles improve the separation of photogenerated electrons and holes. > This facilitates trapping the photoinduced electrons and holes to form more hydroxyl radicals. Therefore, it enhances the photocatalytic efficiency of ZnO.

  9. Optical characteristics of ZnO single crystal grown by the hydrothermal method

    SciTech Connect (OSTI)

    Chen, G. Z.; Yin, J. G. E-mail: yjg@siom.ac.cn; Zhang, L. H.; Zhang, P. X.; Wang, X. Y.; Liu, Y. C.; Zhang, C. L.; Gu, S. L.; Hang, Y.

    2015-12-15

    ZnO single crystals have been grown by the hydrothermal method. Raman scattering and Photoluminescence spectroscopy (PL) have been used to study samples of ZnO that were unannealed or annealed in different ambient gases. It is suggested that the green emission may originate from defects related to copper in our samples.

  10. Mid-Gap Electronic States in Zn1 xMnxO

    SciTech Connect (OSTI)

    Johnson, Claire A.; Kittilstved, Kevin R.; Kaspar, Tiffany C.; Droubay, Timothy C.; Chambers, Scott A.; Salley, G. Mackay; Gamelin, Daniel R.

    2010-09-02

    Electronic absorption, magnetic circular dichroism, photoconductivity, and valence-band X-ray photoelectron (XPS) spectroscopic measurements were performed on epitaxial Zn1 xMnxO films to investigate the origin of the new mid-gap band that appears upon introduction of Mn2+ into the ZnO lattice. Absorption and MCD spectroscopies reveal Mn2+-related intensity at energies below the first excitonic transition of ZnO, tailing well into the visible energy region, with an onset at ~2.2 eV. Photoconductivity measurements show that excitation into this visible band generates mobile charge carriers, consistent with assignment as a Mn2+/3+ photoionization transition. XPS measurements reveal the presence of occupied Mn2+ levels just above the valence-band edge, supporting this assignment. Magnetic circular dichroism measurements additionally show a change in sign and large increase in magnitude of the excitonic Zeeman splitting in Zn1 xMnxO relative to ZnO, suggesting that sp-d exchange in Zn1 xMnxO is not as qualitatively different from those in other II-VI diluted magnetic semiconductors as has been suggested. The singular electronic structure feature of Zn1 xMnxO is its Mn2+/3+ ionization level within the gap, and the influence of this level on other physical properties of Zn1 xMnxO is discussed.

  11. Degradation of ZnO Window Layer for CIGS by Damp-Heat Exposure: Preprint

    SciTech Connect (OSTI)

    Pern, F.J.; To, B.; DeHart, C.; Li, X.; Glick, S. H.; Noufi, R.

    2008-08-01

    This paper summarizes our work with more details and an emphasis on the DH-induced degradation of Al-doped ZnO and Zn1-xMgxO alloys. The other two TCOs, ITO and F:SnO2, are not included here.

  12. Facile synthesis of pompon-like ZnO-Ag nanocomposites and their enhanced photocatalytic performance

    SciTech Connect (OSTI)

    Cheng, Yang; An, Liang; Lan, Jing; Gao, Fang; Tan, Ruiqin; Li, Xiao-min; Wang, Guang-hui

    2013-10-15

    Graphical abstract: - Highlights: Pompon-like ZnO-Ag was prepared via heterothermal and photodeposition method. Pompon-like ZnO-Ag is a excellent photocatalyst for degradation of azo dyes. The photocatalytic and wetting properties were studied upon UV irradiation. The discoloring efficiency of ZnO-Ag heterostructure toward to azo dyes is 99.1%. - Abstract: A series of pompon-like ZnO-Ag nanocomposites were prepared by hydrothermal method and photochemical deposition technique. Several characterizations indicated the successful deposition of Ag nanoparticles on ZnO. As a whole, the as-prepared composites present pompon-like nanostructures with a diameter of ?10 ?m. In detail, the nanostructural, chemical and optical properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), infrared spectroscopy (IR), ultra-visible spectra (UV). The photocatalytic degradation experiments under UV irradiation using Methyl Orange (MO) as a model dye were executed here. The relative results demonstrated that the pompon-like ZnO-Ag nanocomposite with a suitable content of Ag nanoparticles (about 4.82 wt%) has the highest photochemical activity, and the removal ratio of MO was 99.1% after 0.5 h adsorption and subsequent 2 h photodegradation processes. The excellent photocatalytic performance was attributed to the high surface areas of ZnO nanostructure and effectively separation of photo-generated charge on flower-like ZnO by employing Ag nanoparticles as a conductor.

  13. Band-gap tailoring of ZnO by means of heavy Al doping

    SciTech Connect (OSTI)

    Sernelius, B.E.; Berggren, K.; Jin, Z.; Hamberg, I.; Granqvist, C.G.

    1988-06-15

    Films of ZnO:Al were produced by weakly reactive dual-target magnetron sputtering. Optical band gaps, evaluated from spectrophotometric data, were widened in proportion to the Al doping. The widening could be quantitatively reconciled with an effective-mass model for n-doped semiconductors, provided the polar character of ZnO was accounted for.

  14. Magnetic and structural properties of Zn doped MnV{sub 2}O{sub 4}

    SciTech Connect (OSTI)

    Shahi, Prashant; Shukla, K. K.; Singh, Rahul; Chatterjee, Sandip; Das, A.; Ghosh, A. K.; Nigam, A. K.

    2014-04-24

    The magnetization, Neutron diffraction and X-ray diffraction of Zn doped MnV{sub 2}O{sub 4} as a function of temperature have been measured. It has been observed, with increase of Zn the non-linear orientation of Mn spins with the V spins will decrease which effectively decrease the structural transition temperature more rapidly than Curie Temperature.

  15. Luminescence dynamics of bound exciton of hydrogen doped ZnO nanowires

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yoo, Jinkyoung; Yi, Gyu -Chul; Chon, Bonghwan; Joo, Taiha; Wang, Zhehui

    2016-04-11

    In this study, all-optical camera, converting X-rays into visible photons, is a promising strategy for high-performance X-ray imaging detector requiring high detection efficiency and ultrafast detector response time. Zinc oxide is a suitable material for all-optical camera due to its fast radiative recombination lifetime in sub-nanosecond regime and its radiation hardness. ZnO nanostructures have been considered as proper building blocks for ultrafast detectors with spatial resolution in sub-micrometer scale. To achieve remarkable enhancement of luminescence efficiency n-type doping in ZnO has been employed. However, luminescence dynamics of doped ZnO nanostructures have not been thoroughly investigated whereas undoped ZnO nanostructures havemore » been employed to study their luminescence dynamics. Here we report a study of luminescence dynamics of hydrogen doped ZnO nanowires obtained by hydrogen plasma treatment. Hydrogen doping in ZnO nanowires gives rise to significant increase in the near-band-edge emission of ZnO and decrease in averaged photoluminescence lifetime from 300 to 140 ps at 10 K. The effects of hydrogen doping on the luminescent characteristics of ZnO nanowires were changed by hydrogen doping process variables.« less

  16. SrAgZn and EuAgZn with KHg{sub 2}-type structure—Structure, magnetic properties, and {sup 151}Eu Mössbauer spectroscopy

    SciTech Connect (OSTI)

    Gerke, Birgit; Rodewald, Ute Ch.; Niehaus, Oliver; Pöttgen, Rainer

    2013-07-15

    Samples of SrAgZn and EuAgZn were synthesized by reaction of the elements in sealed tantalum crucibles. Both structures were refined on the basis of single crystal X-ray diffractometer data: KHg{sub 2}-type, Imma, a=476.7(1), b=780.9(2), c=810.1(2) pm, R{sub 1}/wR{sub 2}=0.0189/0.0119, 381 F² values for SrAg{sub 1.12}Zn{sub 0.88} and a=474.43(9), b=760.8(2), c=799.0(2) pm, R{sub 1}/wR{sub 2}=0.0226/0.0483, 370 F² values for EuAg{sub 1.17}Zn{sub 0.83} with 13 variables per refinement. Silver and zinc are randomly distributed on the Hg position and build up three-dimensional networks. EuAgZn shows ferromagnetic ordering at 29(1) K. In the temperature range from 75 to 300 K the sample shows Curie–Weiss behaviour with μ{sub eff}=7.87(1) μ{sub B}/Eu atom and θ{sub P}=37.1(1) K, indicating divalent europium. {sup 151}Eu Mössbauer spectroscopic measurements confirmed the divalent state with an isomer shift of −9.31 mm/s at 78 K. Temperature dependent {sup 151}Eu data show first magnetic hyperfine field splitting at 25 K and a saturated magnetization of 17 T at 5.2 K. The temperature dependence can be described by an S=7/2 Brillouin function. - Graphical abstract: The near neighbor coordination of the strontium and europium atoms in SrAg{sub 1.12}Zn{sub 0.88}, EuAg{sub 1.17}Zn{sub 0.83}, and EuAuZn. - Highlights: • Synthesis of new intermetallic zinc compounds SrAgZn and EuAgZn. • Ferromagnetic ordering of EuAgZn at 29 K. • Magnetic hyperfine field splitting in the {sup 151}Eu Mössbauer spectrum.

  17. Hydrothermal synthesis of coral-like Au/ZnO catalyst and photocatalytic degradation of Orange II dye

    SciTech Connect (OSTI)

    Chen, P.K.; Lee, G.J.; Davies, S.H.; Masten, S.J.; Amutha, R.; Wu, J.J.

    2013-06-01

    Highlights: ? Coral-like Au/ZnO was successfully prepared using green synthetic method. ? Gold nanoparticles were deposited on the ZnO structure using NaBH{sub 4} and ?-D-glucose. ? Coral-like Au/ZnO exhibited superior photocatalytic activity to degrade Orange II. - Abstract: A porous coral-like zinc oxide (c-ZnO) photocatalyst was synthesized by the hydrothermal method. The coral-like structure was obtained by precipitating Zn{sub 4}(CO{sub 3})(OH){sub 6}H{sub 2}O (ZnCH), which forms nanosheets that aggregate together to form microspheres with the coral-like structure. X-ray diffraction (XRD) studies indicate that after heating at 550 C the ZnCH microspheres can be converted to ZnO microspheres with a morphology similar to that of ZnCH microspheres. Thermogravimetric analysis (TGA) shows this conversion takes place at approximately 260 C. A simple electrostatic self-assembly method has been employed to uniformly disperse Au nanoparticles (1 wt.%) on the ZnO surface. In this procedure ?-D-glucose was used to stabilize the Au nanoparticles. Scanning electron microscope images indicate that the diameter of coral-like ZnO microspheres (c-ZnO) is about 8 ?m. X-ray diffraction reveals that the ZnO is highly crystalline with a wurtzite structure and the Au metallic particles have an average size of about 13 nm. X-ray photoelectron spectroscopic (XPS) studies have confirmed the presence of ZnO and also showed that the Au is present in the metallic state. The photocatalytic degradation of Orange II dye, with either ultraviolet or visible light, is faster on Au/c-ZnO than on c-ZnO.

  18. Synthesis and characterization of novel WO{sub 3} loaded AgZnO and its photocatalytic activity

    SciTech Connect (OSTI)

    Subash, B.; Krishnakumar, B.; Pandiyan, V.; Swaminathan, M.; Shanthi, M.

    2013-01-15

    Graphical abstract: Display Omitted Highlights: ? A novel WO{sub 3} loaded AgZnO was prepared by a simple solvothermal method. ? Ag traps the electron from both ZnO and WO{sub 3} reducing electrohole recombination. ? WO{sub 3}AgZnO is more efficient than AgZnO, WO{sub 3}ZnO, AgWO{sub 3} and undoped catalysts. ? WO{sub 3}AgZnO material will be much useful for the treatment of dye effluents. -- Abstract: A novel WO{sub 3} loaded AgZnO photocatalyst was successfully synthesized by a simple solvothermal method and characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) images, energy dispersive spectrum (EDS), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), cyclic voltammetry (CV) and BrunauerEmmettTeller (BET) surface area measurements. The photocatalytic activity of WO{sub 3}AgZnO was investigated for the degradation of RR 120 and RO 4 dyes in aqueous solution using UV-A light. WO{sub 3}AgZnO is found to be more efficient than AgZnO, WO{sub 3}ZnO, AgWO{sub 3}, commercial ZnO, prepared ZnO, TiO{sub 2}-P25 and TiO{sub 2} (Merck) at neutral pH for the mineralization of dyes. First time we have reported that novel WO{sub 3} loaded AgZnO has been found to be very efficient for two azo dyes removal when compared to commercially available catalyst (Degussa P25, ZnO (Merck) and TiO{sub 2} (Merck)). The mineralization of dyes has been confirmed by chemical oxygen demand (COD) measurements. A mechanism of degradation has been proposed for the higher efficiency of WO{sub 3}AgZnO.

  19. Atomic layer deposition of zinc sulfide with Zn(TMHD){sub 2}

    SciTech Connect (OSTI)

    Short, Andrew; Jewell, Leila; Doshay, Sage; Church, Carena; Keiber, Trevor; Bridges, Frank; Carter, Sue; Alers, Glenn

    2013-01-15

    The atomic layer deposition (ALD) of ZnS films with Zn(TMHD){sub 2} and in situ generated H{sub 2}S as precursors was investigated, over a temperature range of 150-375 Degree-Sign C. ALD behavior was confirmed by investigation of growth behavior and saturation curves. The properties of the films were studied with atomic force microscopy, scanning electron microscopy, energy-dispersive x-ray spectroscopy, ultraviolet-visible-infrared spectroscopy, and extended x-ray absorption fine structure. The results demonstrate a film that can penetrate a porous matrix, with a local Zn structure of bulk ZnS, and a band gap between 3.5 and 3.6 eV. The ZnS film was used as a buffer layer in nanostructured PbS quantum dot solar cell devices.

  20. Controlled etching of hexagonal ZnO architectures in an alcohol thermal process

    SciTech Connect (OSTI)

    Wu, Junshu [State Key Laboratory of Fine Chemicals, Department of Materials Science and Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116012 (China)] [State Key Laboratory of Fine Chemicals, Department of Materials Science and Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116012 (China); Xue, Dongfeng, E-mail: dfxue@chem.dlut.edu.cn [State Key Laboratory of Fine Chemicals, Department of Materials Science and Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116012 (China)] [State Key Laboratory of Fine Chemicals, Department of Materials Science and Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116012 (China)

    2010-03-15

    An alcohol thermal technique was applied to the controlled growth of hexagonal ZnO architectures via selective chemical etching. ZnO microdisks were produced first under mild alcohol thermal conditions in presence of formamide. Due to a higher surface energy/atomic density of Zn{sup 2+} {l_brace}0 0 0 1{r_brace} than that of the other faces, hexagonal ZnO microring was obtained by selectively etching positive polar surface of disk-like precursor with a high density of planar defects at the center. The selective etching of ZnO is related to its crystallographic characteristics of surface polarity and chemical activities, which opens a new opportunity for the shape-controlled synthesis of wurtzite-structured materials.

  1. Polymer-ZnO nanocomposites foils and thin films for UV protection

    SciTech Connect (OSTI)

    Shanshool, Haider Mohammed; Yahaya, Muhammad; Abdullah, Ibtisam Yahya [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Yunus, Wan Mahmood Mat [Department of Physics, Faculty of Science, University Putra Malaysia, 43400 UPM, Serdang (Malaysia)

    2014-09-03

    The damage of UV radiation on human eye and skin is extensively studied. In the present work, the nanocomposites foils and thin films have been prepared by using casting method and spin coating, respectively. Nanocomposites were prepared by mixing ZnO nanoparticles with Polymethyl methacrylate (PMMA) and Polyvinylidene fluoride (PVDF) as polymer matrix. Different contents of ZnO nanoparticles were used as filler in the nanocomposites. UV-Vis spectra showed very low transmittance in UV region that decreases with increase content of ZnO. PVDF/ZnO samples showed the lowest transmittance. The rough surface of PVDF was observed from SEM image. While a homogeneous dispersion of ZnO nanoparticles in PMMA were indicated by FESEM images.

  2. Emission Properties from ZnO Quantum Dots Dispersed in SiO{sub 2} Matrix

    SciTech Connect (OSTI)

    Panigrahi, Shrabani; Basak, Durga

    2011-07-15

    Dispersion of ZnO quantum dots in SiO{sub 2} matrix has been achieved in two techniques based on StOeber method to form ZnO QDs-SiO{sub 2} nanocomposites. Sample A is formed with random dispersion by adding tetraethyl orthosilicate (TEOS) to an ethanolic solution of ZnO nanoparticles and sample B is formed with a chain-like ordered dispersion by adding ZnO nanoparticles to an already hydrolyzed ethanolic TEOS solution. The photoluminescence spectra of the as-grown nanocomposites show strong emission in the ultraviolet region. When annealed at higher temperature, depending on the sample type, these show strong red or white emission. Interestingly, when the excitation is removed, the orderly dispersed ZnO QDs-SiO{sub 2} composite shows a very bright blue fluorescence visible by naked eyes for few seconds indicating their promise for display applications.

  3. Defect-free ZnO nanorods for low temperature hydrogen sensor applications

    SciTech Connect (OSTI)

    Ranwa, Sapana; Kumar, Mahesh; Kulriya, Pawan K.; Sahu, Vikas Kumar; Kukreja, L. M.

    2014-11-24

    Uniformly distributed and defect-free vertically aligned ZnO nanorods (NRs) with high aspect ratio are deposited on Si by sputtering technique. X-ray diffraction along with transmission electron microscopy studies confirmed the single crystalline wurtzite structure of ZnO. Absence of wide band emission in photoluminescence spectra showed defect-free growth of ZnO NRs which was further conformed by diamagnetic behavior of the NRs. H{sub 2} sensing mechanism based on the change in physical dimension of channel is proposed to explain the fast response (?21.6?s) and recovery times (?27?s) of ZnO NRs/Si/ZnO NRs sensors. Proposed H{sub 2} sensor operates at low temperature (?70?C) unlike the existing high temperature (>150?C) sensors.

  4. The Antimony-Based Type I Clathrate compounds Cs8Cd18Sb28 and Cs8Zn18Sb28**

    SciTech Connect (OSTI)

    Liu, Yi; Wu, Li-Ming; Li, Long-Hua; Du, Shao-Wu; Corbett, John D.; Chen, Ling

    2009-06-17

    The title compounds lie in a new region of phase space for such a structure, and have stoichiometries in accord with a classical Zintl phase formulation. The small semiconductor gaps indicated by DFT calculations are also supported by their diamagnetic susceptibilities.

  5. Chemically deposited CdS by an ammonia-free process for solar cells window layers

    SciTech Connect (OSTI)

    Ochoa-Landin, R.; Sastre-Hernandez, J.; Vigil-Galan, O.; Ramirez-Bon, R.

    2010-02-15

    Chemically deposited CdS window layers were studied on two different transparent conductive substrates, namely indium tin oxide (ITO) and fluorine doped tin oxide (FTO), to determine the influence of their properties on CdS/CdTe solar cells performance. Three types of CdS films obtained from different chemical bath deposition (CBD) processes were studied. The three CBD processes employed sodium citrate as the complexing agent in partial or full substitution of ammonia. The CdS films were studied by X-ray diffraction, optical transmission spectroscopy and atomic force microscopy. CdS/CdTe devices were completed by depositing 3 {mu}m thick CdTe absorbent layers by means of the close-spaced vapor transport technique (CSVT). Evaporated Cu-Au was used as the back contact in all the solar cells. Dark and under illumination J-V characteristic and quantum efficiency measurements were done on the CdS/CdTe devices to determine their conversion efficiency and spectral response. The efficiency of the cells depended on the window layer and on the transparent contact with values between 5.7% and 8.7%. (author)

  6. Molecular Control of the Nanoscale: Effect of PhosphineChalcogenide Reactivity on CdSCdSe Nanocrystal Composition and Morphology

    SciTech Connect (OSTI)

    Ruberu, T. Purnima A.; Albright, Haley R.; Callis, Brandon; Ward, Brittney; Cisneros, Joana; Fan, Hua-Jun; Vela, Javier

    2012-04-22

    We demonstrate molecular control of nanoscale composition, alloying, and morphology (aspect ratio) in CdSCdSe nanocrystal dots and rods by modulating the chemical reactivity of phosphinechalcogenide precursors. Specific molecular precursors studied were sulfides and selenides of triphenylphosphite (TPP), diphenylpropylphosphine (DPP), tributylphosphine (TBP), trioctylphosphine (TOP), and hexaethylphosphorustriamide (HPT). Computational (DFT), NMR (31P and 77Se), and high-temperature crossover studies unambiguously confirm a chemical bonding interaction between phosphorus and chalcogen atoms in all precursors. Phosphinechalcogenide precursor reactivity increases in the order: TPPE < DPPE < TBPE < TOPE < HPTE (E = S, Se). For a given phosphine, the selenide is always more reactive than the sulfide. CdS1xSex quantum dots were synthesized via single injection of a R3PSR3PSe mixture to cadmium oleate at 250 C. X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV/Vis and PL optical spectroscopy reveal that relative R3PS and R3PSe reactivity dictates CdS1xSex dot chalcogen content and the extent of radial alloying (alloys vs core/shells). CdS, CdSe, and CdS1xSex quantum rods were synthesized by injection of a single R3PE (E = S or Se) precursor or a R3PSR3PSe mixture to cadmiumphosphonate at 320 or 250 C. XRD and TEM reveal that the length-to-diameter aspect ratio of CdS and CdSe nanorods is inversely proportional to R3PE precursor reactivity. Purposely matching or mismatching R3PSR3PSe precursor reactivity leads to CdS1xSex nanorods without or with axial composition gradients, respectively. We expect these observations will lead to scalable and highly predictable bottom-up programmed syntheses of finely heterostructured nanomaterials with well-defined architectures and properties that are tailored for precise applications.

  7. Thin Metal Oxide Films to Modify a Window Layer in CdTe-Based Solar Cells for Improved Performance

    SciTech Connect (OSTI)

    Lemmon, John P.; Polikarpov, Evgueni; Bennett, Wendy D.; Kovarik, Libor

    2012-05-25

    We report on CdS/CdTe photovoltaic devices that contain a thin Ta₂O₅ film deposited onto the CdS window layer by sputtering. We show that for thicknesses below 5 nm, Ta₂O₅ films between CdS and CdTe positively affect the solar cell performance, improving JSC, VOC, and the cell power conversion efficiency despite the insulating nature of the interlayer material. Using the Ta₂O₅ interlayer, a VOC gain of over 100 mV was demonstrated compared to a CdTe/CdS baseline. Application of a 1nm Ta₂O₅ interlayer enabled the fabrication of CdTe solar cells with extremely thin (less than 30 nm) CdS window layers. The efficiency of these cells exceeded that of a base line cell with 95 nm of CdS.

  8. High-Efficiency, Commercial Ready CdTe Solar Cells

    SciTech Connect (OSTI)

    Sites, James R.

    2015-11-19

    Colorado State’s F-PACE project explored several ways to increase the efficiency of CdTe solar cells and to better understand the device physics of those cells under study. Increases in voltage, current, and fill factor resulted in efficiencies above 17%. The three project tasks and additional studies are described in detail in the final report. Most cells studied were fabricated at Colorado State using an industry-compatible single-vacuum closed-space-sublimation (CSS) chamber for deposition of the key semiconductor layers. Additionally, some cells were supplied by First Solar for comparison purposes, and a small number of modules were supplied by Abound Solar.

  9. Plasmonic excitations in ZnO/Ag/ZnO multilayer systems: Insight into interface and bulk electronic properties

    SciTech Connect (OSTI)

    Philipp, Martin; Knupfer, Martin; Buechner, Bernd; Gerardin, Hadia

    2011-03-15

    Electron energy-loss spectroscopy experiments in transmission were carried out on silver-based multi-layer systems, consisting of a silver layer of various thicknesses (8, 10 and 50 nm) sandwiched between two Al-doped ZnO layers. The films were produced by magnetron sputtering using potassium bromide single crystals as substrates. The electronic structure of these systems was probed and analyzed with respect to their plasmonic excitations, which can be basically split up into excitations of the electrons in the bulk silver and excitations at the ZnO:Al/Ag interface. A detailed examination of the momentum dependence of the plasmon peaks revealed a positive dispersion for both, the volume and the interface plasmon, where only for the first one a quadratic behavior (as expected for a free electron gas) could be observed. Furthermore, the peak width was analyzed and set into relation to electrical conductivity measurements by calculating the plasmon lifetime and the electron scattering rate. Here, a good agreement between these different methods was obtained.

  10. Advanced CdTe Photovoltaic Technology: September 2007 - March 2009

    SciTech Connect (OSTI)

    Barth, K.

    2011-05-01

    During the last eighteen months, Abound Solar (formerly AVA Solar) has enjoyed significant success under the SAI program. During this time, a fully automated manufacturing line has been developed, fabricated and commissioned in Longmont, Colorado. The facility is fully integrated, converting glass and semiconductor materials into complete modules beneath its roof. At capacity, a glass panel will enter the factory every 10 seconds and emerge as a completed module two hours later. This facility is currently undergoing trials in preparation for large volume production of 120 x 60 cm thin film CdTe modules. Preceding the development of the large volume manufacturing capability, Abound Solar demonstrated long duration processing with excellent materials utilization for the manufacture of high efficiency 42 cm square modules. Abound Solar prototype modules have been measured with over 9% aperture area efficiency by NREL. Abound Solar demonstrated the ability to produce modules at industry leading low costs to NREL representatives. Costing models show manufacturing costs below $1/Watt and capital equipment costs below $1.50 per watt of annual manufacturing capacity. Under this SAI program, Abound Solar supported a significant research and development program at Colorado State University. The CSU team continues to make progress on device and materials analysis. Modeling for increased device performance and the effects of processing conditions on properties of CdTe PV were investigated.

  11. Experimental determination of valence band offset at PbTe/CdTe(111)

    Office of Scientific and Technical Information (OSTI)

    heterojunction interface by x-ray photoelectron spectroscopy (Journal Article) | SciTech Connect Experimental determination of valence band offset at PbTe/CdTe(111) heterojunction interface by x-ray photoelectron spectroscopy Citation Details In-Document Search Title: Experimental determination of valence band offset at PbTe/CdTe(111) heterojunction interface by x-ray photoelectron spectroscopy Lattice-matched PbTe/CdTe(111) heterojunction interfaces were studied using x-ray photoelectron

  12. Critical Decision 2 (CD-2) ESAAB and PMRC Brief Template | Department of

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Energy 2 (CD-2) ESAAB and PMRC Brief Template Critical Decision 2 (CD-2) ESAAB and PMRC Brief Template Template for briefing Critical Decisions to the ESAAB and/or PMRC July 2015 Office presentation icon Template Key Resources PMCDP EVMS PARS IIe FPD Resource Center PM Newsletter Forms and Templates More Documents & Publications Baseline Change Proposal (BCP) ESAAB and PMRC Brief Template DOE Project Management Risk Committee (PMRC) SOP Critical Decision 2 (CD-2) ESAAB and PMRC Brief

  13. Photoluminescence Imaging of Large-Grain CdTe for Grain Boundary

    Office of Scientific and Technical Information (OSTI)

    Characterization (Conference) | SciTech Connect Photoluminescence Imaging of Large-Grain CdTe for Grain Boundary Characterization Citation Details In-Document Search Title: Photoluminescence Imaging of Large-Grain CdTe for Grain Boundary Characterization In this work, we use photoluminescence (PL) imaging to characterize CdTe grain boundary recombination. We use a silicon megapixel camera and green (532 nm) laser diodes for excitation. A microscope objective lens system is used for high

  14. Component Overpressure Growth and Characterization of High Resistivity CdTe

    Office of Scientific and Technical Information (OSTI)

    Crystals for Radiation Detectors (Journal Article) | SciTech Connect Component Overpressure Growth and Characterization of High Resistivity CdTe Crystals for Radiation Detectors Citation Details In-Document Search Title: Component Overpressure Growth and Characterization of High Resistivity CdTe Crystals for Radiation Detectors Spectrometer-grade CdTe single crystals with resistivities higher than 10{sup 9} {Omega} cm have been grown by the modified Bridgman method using zone-refined

  15. Low temperature atomic layer deposited ZnO photo thin film transistors

    SciTech Connect (OSTI)

    Oruc, Feyza B.; Aygun, Levent E.; Donmez, Inci; Biyikli, Necmi; Okyay, Ali K.; Yu, Hyun Yong

    2015-01-01

    ZnO thin film transistors (TFTs) are fabricated on Si substrates using atomic layer deposition technique. The growth temperature of ZnO channel layers are selected as 80, 100, 120, 130, and 250?C. Material characteristics of ZnO films are examined using x-ray photoelectron spectroscopy and x-ray diffraction methods. Stoichiometry analyses showed that the amount of both oxygen vacancies and interstitial zinc decrease with decreasing growth temperature. Electrical characteristics improve with decreasing growth temperature. Best results are obtained with ZnO channels deposited at 80?C; I{sub on}/I{sub off} ratio is extracted as 7.8 10{sup 9} and subthreshold slope is extracted as 0.116 V/dec. Flexible ZnO TFT devices are also fabricated using films grown at 80?C. I{sub D}V{sub GS} characterization results showed that devices fabricated on different substrates (Si and polyethylene terephthalate) show similar electrical characteristics. Sub-bandgap photo sensing properties of ZnO based TFTs are investigated; it is shown that visible light absorption of ZnO based TFTs can be actively controlled by external gate bias.

  16. Photoelectrochemical Stability and Alteration Products of n-Type Single-Crystal ZnO Photoanodes

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Paulauskas, I. E.; Jellison, G. E.; Boatner, L. A.; Brown, G. M.

    2011-01-01

    The photoelectrochemical stability and surface-alteration characteristics of doped and undoped n-type ZnO single-crystal photoanode electrodes were investigated. The single-crystal ZnO photoanode properties were analyzed using current-voltage measurements plus spectral and time-dependent quantum-yield methods. These measurements revealed a distinct anodic peak and an accompanying cathodic surface degradation process at negative potentials. The features of this peak depended on time and the NaOH concentration in the electrolyte, but were independent of the presence of electrode illumination. Current measurements performed at the peak indicate that charging and discharging effects are apparently taking place at the semiconductor/electrolyte interface. This result is consistent with themore » significant reactive degradation that takes place on the ZnO single crystal photoanode surface and that ultimately leads to the reduction of the ZnO surface to Zn metal. The resulting Zn-metal reaction products create unusual, dendrite-like, surface alteration structural features that were analyzed using x-ray diffraction, energy-dispersive analysis, and scanning electron microscopy. ZnO doping methods were found to be effective in increasing the n-type character of the crystals. Higher doping levels result in smaller depletion widths and lower quantum yields, since the minority carrier diffusion lengths are very short in these materials.« less

  17. Modifying structure-sensitive reactions by addition of Zn to Pd

    SciTech Connect (OSTI)

    Childers, David J.; Schweitzer, Neil M.; Kamali Shahari, Seyed Mehdi; Rioux, Robert M.; Miller, Jeffrey T.; Meyer, Randall J.

    2014-10-01

    Silica-supported Pd and PdZn nanoparticles of a similar size were evaluated for neopentane hydrogenolysis/isomerization and propane hydrogenolysis/dehydrogenation. Monometallic Pd showed high neopentane hydrogenolysis selectivity. Addition of small amounts of Zn to Pd lead PdZn scatters in the EXAFS spectrum and an increase in the linear bonded CO by IR. In addition, the neopentane turnover rate decreased by nearly 10 times with little change in the selectivity. Increasing amounts of Zn lead to greater PdZn interactions, higher linear-to-bridging CO ratios by IR and complete loss of neopentane conversion. Pd NPs also had high selectivity for propane hydrogenolysis and thus were poorly selective for propylene. The PdZn bimetallic catalysts, however, were able to preferentially catalyze dehydrogenation, were not active for propane hydrogenolysis, and thus were highly selective for propylene formation. The decrease in hydrogenolysis selectivity was attributed to the isolation of active Pd atoms by inactive metallic Zn,demonstrating that hydrogenolysis requires a particular reactive ensemble whereas propane dehydrogenation does not.

  18. Ethanol Steam Reforming on Co/CeO2: The Effect of ZnO Promoter

    SciTech Connect (OSTI)

    Davidson, Stephen; Sun, Junming; Wang, Yong

    2013-12-02

    A series of ZnO promoted Co/CeO2 catalysts were synthesized and characterized using XRD, TEM, H2-TPR, CO chemisorption, O2-TPO, IR-Py, and CO2-TPD. The effects of ZnO on the catalytic performances of Co/CeO2 were studied in ethanol steam reforming. It was found that the addition of ZnO facilitated the oxidation of Co0 via enhanced oxygen mobility of the CeO2 support which decreased the activity of Co/CeO2 in C–C bond cleavage of ethanol. 3 wt% ZnO promoted Co/CeO2 exhibited minimum CO and CH4 selectivity and maximum CO2 selectivity. This resulted from the combined effects of the following factors with increasing ZnO loading: (1) enhanced oxygen mobility of CeO2 facilitated the oxidation of CHx and CO to form CO2; (2) increased ZnO coverage on CeO2 surface reduced the interaction between CHx/CO and Co/CeO2; and (3) suppressed CO adsorption on Co0 reduced CO oxidation rate to form CO2. In addition, the addition of ZnO also modified the surface acidity and basicity of CeO2, which consequently affected the C2–C4 product distributions.

  19. High electron mobility ZnO film for high-performance inverted polymer solar cells

    SciTech Connect (OSTI)

    Lv, Peiwen; Chen, Shan-Ci; Zheng, Qingdong; Huang, Feng Ding, Kai

    2015-04-20

    High-quality ZnO films (ZnO-MS) are prepared via magnetron sputtering deposition with a high mobility of about 2 cm{sup 2}/(V·s) and are used as electron transport layer for inverted polymer solar cells (PSCs) with polymer poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′] dithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate]:[6,6]-phenyl C71-butyric acid methyl ester as the active layer. A significant improvement of J{sub SC}, about 20% enhancement in contrast to the devices built on sol-gel derived ZnO film (ZnO-Sol), is found in the ZnO-MS based device. High performance ZnO-MS based PSCs exhibit power conversion efficiency (PCE) up to 8.55%, which is much better than the device based on ZnO-Sol (PCE = 7.78%). Further research on cathode materials is promising to achieve higher performance.

  20. Performance evaluation of ZnO–CuO hetero junction solid state room temperature ethanol sensor

    SciTech Connect (OSTI)

    Yu, Ming-Ru; Suyambrakasam, Gobalakrishnan; Wu, Ren-Jang; Department of Nanotechnology, School of Interdisciplinary Courses, Noorul Islam Centre for Higher Education, Noorul Islam University, Kumaracoil 629180, Tamil Nadu ; Chavali, Murthy; Department of Applied Chemistry, Providence University, 200 Chungchi Road, Shalu, Taichung Hsien 433, Taiwan, R.O.C

    2012-07-15

    Graphical abstract: Sensor response (resistance) curves of time were changed from 150 ppm to 250 ppm alcohol concentration of ZnO–CuO 1:1. The response and recovery times were measured to be 62 and 83 s, respectively. The sensing material ZnO–CuO is a high potential alcohol sensor which provides a simple, rapid and highly sensitive alcohol gas sensor operating at room temperature. Highlights: ► The main advantages of the ethanol sensor are as followings. ► Novel materials ZnO–CuO ethanol sensor. ► The optimized ZnO–CuO hetero contact system. ► A good sensor response and room working temperature (save energy). -- Abstract: A semiconductor ethanol sensor was developed using ZnO–CuO and its performance was evaluated at room temperature. Hetero-junction sensor was made of ZnO–CuO nanoparticles for sensing alcohol at room temperature. Nanoparticles were prepared by hydrothermal method and optimized with different weight ratios. Sensor characteristics were linear for the concentration range of 150–250 ppm. Composite materials of ZnO–CuO were characterized using X-ray diffraction (XRD), temperature-programmed reduction (TPR) and high-resolution transmission electron microscopy (HR-TEM). ZnO–CuO (1:1) material showed maximum sensor response (S = R{sub air}/R{sub alcohol}) of 3.32 ± 0.1 toward 200 ppm of alcohol vapor at room temperature. The response and recovery times were measured to be 62 and 83 s, respectively. The linearity R{sup 2} of the sensor response was 0.9026. The sensing materials ZnO–CuO (1:1) provide a simple, rapid and highly sensitive alcohol gas sensor operating at room temperature.

  1. High Efficiency CdTe and CIGS Thin Film Solar Cells: Highlights...

    Office of Scientific and Technical Information (OSTI)

    High Efficiency CdTe and CIGS Thin Film Solar Cells: Highlights of the Technologies Challenges Acknowledgement: Work performed at NREL for US DOE under contract No....

  2. In vivo Prompt Gamma Neutron Activation Analysis Facility for Total Body Nitrogen and Cd

    SciTech Connect (OSTI)

    Munive, Marco; Revilla, Angel; Solis, Jose L.

    2007-10-26

    A Prompt Gamma Neutron Activation Analysis (PGNAA) system has been designed and constructed to measure the total body nitrogen and Cd for in vivo studies. An aqueous solution of KNO{sub 3} was used as phantom for system calibration. The facility has been used to monitor total body nitrogen (TBN) of mice and found that is related to their diet. Some mice swallowed diluted water with Cl{sub 2}Cd, and the presence of Cd was detected in the animals. The minimum Cd concentration that the system can detect was 20 ppm.

  3. Nanoscale imaging of photocurrent and efficiency in CdTe solar...

    Office of Scientific and Technical Information (OSTI)

    cells The local collection characteristics of grain interiors and grain boundaries in thin film CdTe polycrystalline solar cells are investigated using scanning photocurrent...

  4. DOE CD-1/2/3a Review of the MINERvA Project

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    1/2/3a Review of the MINERvA Project Main INjector ExpeRiment v-A December 5, 2006 | Overview | CD-2 Documentation| CD-3a Documentation|Other Documents| Overview of Charge and Experiment MINERvA Overview (pdf) DOE CD-2 and CD-3a Scorecard (pdf) Review Presentations by MINERvA Project Team Project Overview (pdf) Scintillators (WBS 1.0) WLS Fibers (WBS 2.0) and Clear Fiber Cables (WBS 4.0) (pdf) Phototubes (WBS 6.0) PMT Housing (WBS 5.0) and Electronics and DAQ (WBS 7.0) (pdf) Scintillator Plane

  5. White luminescence from CdS nanocrystals under the blue light excitation

    SciTech Connect (OSTI)

    Li, Bo; Zhang, Xiaosong Li, Lan; Li, Mengzhen; Xu, Jianping; Hong, Yuan

    2014-06-01

    Trap-rich CdS nanocrystals were synthesized by employing CdSt{sub 2} and sulfur as precursors via thermal decomposition. Furthermore, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), absorption and photoluminescence (PL) spectra were used to characterize structure, morphology and luminescence properties of CdS nanocrystals (NCs). CdS NCs have a broad emission across 500–700 nm under the excitation of blue light with 460 nm, consequently, white light can be produced by mixing broad emission from CdS NCs excited by blue light, with the remaining blue light. In addition, the broad emission generation is closely and inseparably related to surface defects. Moreover, LaMer model was used to explain the phenomenon that the intensity of the trap emission gradually decreases as the reaction time increases in contrast with that of the band-edge emission. - Graphical abstract: Trap-rich CdS nanocrystals were synthesized. Furthermore, white light is produced by mixing broad emission across 500–700 nm from CdS NCs excited by blue light, in combination with the remaining blue light. - Highlights: • Trap-rich CdS nanocrystals were synthesized. • CdS NCs have a broad emission across 500–700 nm under the excitation of blue light. • White light can be produced by mixing broad emission with the remaining blue light.

  6. Characterization and Analysis of CIGS and CdTE Solar Cells: December 2004 - July 2008

    SciTech Connect (OSTI)

    Sites, J. R.

    2009-01-01

    The work reported here embodies a device-physics approach based on careful measurement and interpretation of data from CIGS and CdTe solar cells.

  7. CYP2E1-dependent and leptin-mediated hepatic CD57 expression on CD8 + T cells aid progression of environment-linked nonalcoholic steatohepatitis

    SciTech Connect (OSTI)

    Seth, Ratanesh Kumar; Das, Suvarthi; Kumar, Ashutosh; Chanda, Anindya; Kadiiska, Maria B.; Michelotti, Gregory; Manautou, Jose; Diehl, Anna Mae; Chatterjee, Saurabh

    2014-01-01

    Environmental toxins induce a novel CYP2E1/leptin signaling axis in liver. This in turn activates a poorly characterized innate immune response that contributes to nonalcoholic steatohepatitis (NASH) progression. To identify the relevant subsets of T-lymphocytes in CYP2E1-dependent, environment-linked NASH, we utilized a model of diet induced obese (DIO) mice that are chronically exposed to bromodichloromethane. Mice deficient in CYP2E1, leptin (ob/ob mice), or both T and B cells (Pfp/Rag2 double knockout (KO) mice) were used to delineate the role of each of these factors in metabolic oxidative stress-induced T cell activation. Results revealed that elevated levels of lipid peroxidation, tyrosyl radical formation, mitochondrial tyrosine nitration and hepatic leptin as a consequence of metabolic oxidative stress caused increased levels of hepatic CD57, a marker of peripheral blood lymphocytes including NKT cells. CD8 + CD57 + cytotoxic T cells but not CD4 + CD57 + cells were significantly decreased in mice lacking CYP2E1 and leptin. There was a significant increase in the levels of T cell cytokines IL-2, IL-1?, and IFN-? in bromodichloromethane exposed DIO mice but not in mice that lacked CYP2E1, leptin or T and B cells. Apoptosis as evidenced by TUNEL assay and levels of cleaved caspase-3 was significantly lower in leptin and Pfp/Rag2 KO mice and highly correlated with protection from NASH. The results described above suggest that higher levels of oxidative stress-induced leptin mediated CD8 + CD57 + T cells play an important role in the development of NASH. It also provides a novel insight of immune dysregulation and may be a key biomarker in NASH. - Highlights: Metabolic oxidative stress caused increased levels of hepatic CD57 expression. CD8+ CD57+ cytotoxic T cells were decreased in mice lacking CYP2E1 and leptin. There was a significant increase in T cell cytokines in toxin-treated mice. Apoptosis was significantly lower in leptin and Pfp/Rag2 KO mice. Leptin mediated CD8+CD57+ T cells play an important role in NASH.

  8. High-throughput manufacturing of thin-film CdS/CdTe photovoltaic modules. Annual subcontract report, 16 September 1996--15 January 1998

    SciTech Connect (OSTI)

    Sandwisch, D.W. [Solar Cells, Inc., Toledo, OH (United States)

    1998-08-01

    Cadmium telluride (CdTe) is recognized as one of the leading materials for low-cost photovoltaic modules. Solar Cells, Inc., has developed this technology and is scaling its pilot production capabilities to a multi-megawatt level. The Photovoltaic Manufacturing Technology (PVMaT) subcontract supports these efforts. Activities during the third phase of the program concentrated on process development, equipment design and testing, quality assurance, ES and H programs, and large-scale next-generation coating-system prototype development. These efforts broadly addressed the issues of the manufacturing process for producing thin-film, monolithic CdS/CdTe photovoltaic modules.

  9. H2S removal with ZnO during fuel processing for PEM fuel cell applications

    SciTech Connect (OSTI)

    Li, Liyu; King, David L.

    2006-09-15

    The possibility of using ZnO as a H2S absorbent to protect catalysts in the gasoline and diesel fuel processor for PEM fuel cell applications was studied. It is possible to use commercial ZnO absorbent as a guard bed to protect the PROX catalyst and PEM fuel cell. However, it is not feasible to use ZnO to protect high and low temperature WGS catalysts, most likely due to COS formation via reactions CO + H2S = COS + H2 and CO2 + H2S = COS + H2O.

  10. Phosphorescence quenching by mechanical stimulus in CaZnOS:Cu

    SciTech Connect (OSTI)

    Tu, Dong; Kamimura, Sunao; Xu, Chao-Nan; Fujio, Yuki; Sakata, Yoshitaro; Ueno, Naohiro

    2014-07-07

    We have found that phosphorescence intensity of CaZnOS:Cu decreased visibly under an applied load. This mechanical quenching (MQ) of phosphorescence in CaZnOS:Cu corresponded to the mechanical stimuli. We have thus demonstrated that the MQ of CaZnOS:Cu could be used for visualizing stress distributions in practical applications. We propose that MQ arises from non-radiative recombination due to electron-transfer from trap levels to non-radiative centers as a result of the mechanical load.

  11. Luminescent properties of solution-grown ZnO nanorods. (Journal Article) |

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Luminescent properties of solution-grown ZnO nanorods. Citation Details In-Document Search Title: Luminescent properties of solution-grown ZnO nanorods. The optical properties of solution-grown ZnO nanorods were investigated using photoluminescence and cathodoluminescence. The as-grown nanorods displayed a broad yellow-orange sub-band-gap luminescence and a small near-band-gap emission peak. The sub-band-gap luminescence can only be observed when exciting above band gap.

  12. Magnetism of Co doped ZnO with Al codoping: carrier induced mechanisms versus extrinsic origins

    SciTech Connect (OSTI)

    Ney, A.; Ney, V.; Ye, S.; Ollefs, K.; Kammermeier, T.; Kaspar, Tiffany C.; Chambers, Scott A.; Wilhelm, F.; Rogalev, A.

    2010-07-23

    Dilute magnetic semiconductors (DMS) which exhibit ferromagnetism (FM) at and above room temperature are a highly desirable class of materials for future spin- tronics devices. Zn1?xCoxO (Co:ZnO) is a heavily studied DMS material in this context. Although controversially discussed in the literature, there is a growing con- sensus, that phase-pure Co:ZnO is paramagnetic (PM)[13]. Altering the preparation conditions can easily lead to phase separation and consequently superparam- agnetism (SPM) [3]. Nonetheless there are recent experimental data claiming that FM can be switched on inCo:ZnO by controlling the carrier concentration [4]. On the other hand, no FM was found in structurally excellent Al-codoped Co:ZnO [5]. However, in the latter work the magnetic characterization was restricted to room temperature measurements. In parallel, theory has also revealed that defect-free, insulating Co:ZnO is not ferromagnetic [6, 7] whereas the role of n-type carriers remains under debate, ranging from ferromagnetic coupling [8], or oscil- latory behavior with Co-Co distance [9] to antiferromagnetic coupling [10]. It is rather common to manipulate the n-type carrier concentration of ZnO by Al-doping to yield high conductivity [4, 11]. On the other hand, it had been shown that Al-codoping of Co:ZnO may promote the onset of phase separation [11]. It is extremely difficult to detect such secondary Co-containing phases even with the most careful x-ray diffraction (XRD) analysis [11, 12] or depth-profiling photoelectron spectroscopy (DP-XPS) [13]. Such careful materials characterization is lacking in Ref. [4]. An alternative to extensive XRD or DP-XPS to look for potential phase separation in Co:ZnO is the combination of x-ray absorption near edge spectra (XANES), x-ray linear dichroism (XLD), and x-ray magnetic circular dichroism (XMCD). This suite of atom-specific x-ray spectroscopies nicely complements integral superconducting quantum interference device (SQUID) magnetometry. For example, combined XLD simulations and experiments at the Co K-edge have been used to verify the phase purity of Co:ZnO [2] and characteristic spectroscopic signatures with appropriate quality thresholds for PM and SPM have been identified recently in the XANES and XMCD at the Co K-edge of Co:ZnO [3]. Along the same line, a careful combination of XANES and extended x-ray absorption fine structure (EXAFS) was employed to study Co:ZnO films similar to those in [4] which found evidence for Co(0) secondary phases [14].

  13. Yb-Zn-Al ternary system: CaCu{sub 5}-type derived compounds in the

    Office of Scientific and Technical Information (OSTI)

    zinc-rich corner (Journal Article) | SciTech Connect Yb-Zn-Al ternary system: CaCu{sub 5}-type derived compounds in the zinc-rich corner Citation Details In-Document Search Title: Yb-Zn-Al ternary system: CaCu{sub 5}-type derived compounds in the zinc-rich corner As part of a study of the Yb-Zn-Al system, this first article reports the synthesis and crystal structure of four compounds. The crystal structures were determined by single crystal diffractometer data for three of them: Yb{sub

  14. Ni, Fe Co-doped ZnO nanoparticles synthesized by solution combustion method

    SciTech Connect (OSTI)

    Dhiman, Pooja Chand, Jagdish Verma, S. Sarveena, Singh, M.

    2014-04-24

    This paper outlines the synthesis and characterization of Ni-Fe co-doped ZnO nanoparticles by facile solution combustion method. The structural characterization by XRD confirmed the phase purity of the samples. Surface morphology studied by scanning electron microscope revealed cubic type shape of grains. EDS analysis conformed the elemental composition. Higher value of DC electrical conductivity and less band gap for co-doped ZnO from UV-Vis studies confirmed the change in defect chemistry of ZnO Matrix.

  15. Synthesis and characterization of ZnO nanostructured film for optoelectronic applications

    SciTech Connect (OSTI)

    Kumar, Vijay E-mail: sanjeev04101977@gmail.com; Singh, Harpreetpal

    2015-05-15

    ZnO nanostructured film is synthesized by solution combustion technique. X-ray diffraction (XRD) studies show that preferred orientation is along (101) confirming the hexagonal wurtzite phase and no secondary phase is observed. The rietveld refinement of the XRD data was used to calculate different lattice parameters. I-V characterization of ZnO film shows non linear behavior. These ZnO films are photosensitive, may be due to defect states. This property of these films can be utilized in optoelectronic applications.

  16. Structural studies and band gap tuning of Cr doped ZnO nanoparticles

    SciTech Connect (OSTI)

    Srinet, Gunjan Kumar, Ravindra Sajal, Vivek

    2014-04-24

    Structural and optical properties of Cr doped ZnO nanoparticles prepared by the thermal decomposition method are presented. X-ray diffraction studies confirmed the substitution of Cr on Zn sites without changing the wurtzite structure of ZnO. Modified form of W-H equations was used to calculate various physical parameters and their variation with Cr doping is discussed. Significant red shift was observed in band gap, i.e., a band gap tuning is achieved by Cr doping which could eventually be useful for optoelectronic applications.

  17. Polarity effects in the x-ray photoemission of ZnO and other wurtzite semiconductors

    SciTech Connect (OSTI)

    Allen, M. W.; Zemlyanov, D. Y.; Waterhouse, G. I. N.; Metson, J. B.; Veal, T. D.; McConville, C. F.; Durbin, S. M.

    2011-03-07

    Significant polarity-related effects were observed in the near-surface atomic composition and valence band electronic structure of ZnO single crystals, investigated by x-ray photoemission spectroscopy using both Al K{sub {alpha}} (1486.6 eV) and synchrotron radiation (150 to 1486 eV). In particular, photoemission from the lowest binding energy valence band states was found to be significantly more intense on the Zn-polar face compared to the O-polar face. This is a consistent effect that can be used as a simple, nondestructive indicator of crystallographic polarity in ZnO and other wurtzite semiconductors.

  18. ZnO/porous-Si and TiO{sub 2}/porous-Si nanocomposite nanopillars

    SciTech Connect (OSTI)

    Wang, Dong, E-mail: dong.wang@tu-ilmenau.de; Yan, Yong; Schaaf, Peter [Chair Materials for Electronics, Institute of Materials Engineering and Institute of Micro- and Nanotechnologies MacroNano, TU Ilmenau, Gustav-Kirchhoff-Str. 5, 98693 Ilmenau (Germany); Sharp, Thomas [Oxford Instruments Plasma Technology Ltd., Yatton, Bristol BS49 4AP (United Kingdom); Schnherr, Sven; Ronning, Carsten [Institute for Solid State Physics, Friedrich Schiller University Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Ji, Ran [SUSS MicroTec Lithography GmbH, Schleissheimer Str. 90, 85748 Garching (Germany)

    2015-01-01

    Porous Si nanopillar arrays are used as templates for atomic layer deposition of ZnO and TiO{sub 2}, and thus, ZnO/porous-Si and TiO{sub 2}/porous-Si nanocomposite nanopillars are fabricated. The diffusion of the precursor molecules into the inside of the porous structure occurs via Knudsen diffusion and is strongly limited by the small pore size. The luminescence of the ZnO/porous-Si nanocomposite nanopillars is also investigated, and the optical emission can be changed and even quenched after a strong plasma treatment. Such nanocomposite nanopillars are interesting for photocatalysis and sensors.

  19. Highly Emissive Multiexcitons in Steady-State Photoluminescence of Individual Giant CdSe/CdS Core/Shell Nanocrystals

    SciTech Connect (OSTI)

    Htoon, Han; Malko, Anton V.; Bussian, David A.; Vela, Javier; Chen, Yongfen; Hollingsworth, Jennifer A.; Klimov, Victor I.

    2010-06-01

    The development of nanocrystal quantum dots (NQDs) with suppressed nonradiative Auger recombination has been an important goal in colloidal nanostructure research motivated by the needs of prospective applications in lasing devices, light-emitting diodes, and photovoltaic cells. Here, we conduct single-nanocrystal spectroscopic studies of recently developed core-shell NQDs (so-called giant NQDs) that comprise a small CdSe core surrounded by a 16-monolayer-thick CdS shell. Using both continuous-wave and pulsed excitation, we observe strong emission features due both to neutral and charged biexcitons, as well as multiexcitons of higher order. The development of pronounced multiexcitonic peaks in steady-state photoluminescence of individual nanocrystals, as well as continuous growth of the emission intensity in the range of high pump levels, point toward a significant suppression of nonradiative Auger decay that normally renders multiexcitons nonemissive. The unusually high multiexciton emission efficiencies in these systems open interesting opportunities for studies of multiexciton phenomena using well-established methods of single-dot spectroscopy, as well as new exciting prospects for applications, that have previously been hampered by nonradiative Auger decay.

  20. X-ray absorption studies of mixed salt polymer electrolytes: ZnBr{sub 2}/CaBr{sub 2}-PEO, ZnBr{sub 2}/LiBr-PEO, and ZnBr{sub 2}/RbBr-PEO complexes

    SciTech Connect (OSTI)

    McBreen, J.; Yang, X.Q.; Lee, H.S.; Okamoto, Y.

    1995-02-01

    Polyethylene oxide (PEO)-salt systems are an important new class of electrolytes that are being considered for many uses. X-ray absorption (XAS) studies of ZnBr{sub 2}-PEO complexes, at the Zn K edge, at temperatures between 25 and 120 C, indicate that additions of bromide salts of Li, Rb, or Ca result in the formation of ZnBr{sub 4}{sup {minus} 2} complexes with a Zn-Br bond length of 2.42 {angstrom}. XAS, at the Rb K edge, in mixed RbBr/ZnBr{sub 2}-PEO complexes with an excess of ZnBr{sub 2}, shows that the ZnBr{sub 2} causes the RbBr to dissolve in the polymer. The Rb{sup +} ions are weakly complexed with the PEO with an Rb-O bond distance of 2.93 {angstrom}.

  1. Coulomb Excitation of Neutron-Rich Zn Isotopes: First Observation of the 2{sub 1}{sup +} State in {sup 80}Zn

    SciTech Connect (OSTI)

    Van de Walle, J.; Cocolios, T. E.; Huyse, M.; Ivanov, O.; Mayet, P.; Raabe, R.; Sawicka, M.; Stefanescu, I.; Duppen, P. van; Aksouh, F.; Behrens, T.; Gernhauser, R.; Kroell, T.; Kruecken, R.; Bildstein, V.; Blazhev, A.; Eberth, J.

    2007-10-05

    Neutron-rich, radioactive Zn isotopes were investigated at the Radioactive Ion Beam facility REX-ISOLDE (CERN) using low-energy Coulomb excitation. The energy of the 2{sub 1}{sup +} state in {sup 78}Zn could be firmly established and for the first time the 2{sup +}{yields}0{sub 1}{sup +} transition in {sup 80}Zn was observed at 1492(1) keV. B(E2,2{sub 1}{sup +}{yields}0{sub 1}{sup +}) values were extracted for {sup 74,76,78,80}Zn and compared to large scale shell model calculations. With only two protons outside the Z=28 proton core, {sup 80}Zn is the lightest N=50 isotone for which spectroscopic information has been obtained to date. Two sets of advanced shell model calculations reproduce the observed B(E2) systematics. The results for N=50 isotones indicate a good N=50 shell closure and a strong Z=28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus {sup 78}Ni.

  2. Imaging and characterization of piezoelectric potential in a single bent ZnO microwire

    SciTech Connect (OSTI)

    Wang, Chiang-Lun; Chen, Jhih-Wei; Chen, Yi-Chun; Wu, Chung-Lin; Tsai, Shu-Ju; Lin, Kai-Hsiang; Hsu, Hsu-Cheng

    2014-09-22

    We achieved direct visualization of the piezoelectric potentials in a single bent ZnO microwire (MW) using focused synchrotron radiation (soft x-ray) scanning photoelectron spectro-microscopy. Using radial-line scan across the bent section of ZnO MW, the characteristic core-level shifts were directly related to the spatial distribution of piezoelectric potentials perpendicular to the ZnO polar direction. Using piezoelectric modeling in ZnO, we delineated the band structure distortion and carrier concentration change from tensile to compressed sides by combining the spatial resolved cathodoluminescence characteristics in an individual microwire. This spectro-microscopic technique allows imaging and identification of the electric-mechanical couplings in piezoelectric micro-/nano-wire systems.

  3. Determination of the spontaneous polarization of wurtzite (Mg,Zn)O

    SciTech Connect (OSTI)

    Stölzel, Marko Müller, Alexander; Benndorf, Gabriele; Lorenz, Michael; Grundmann, Marius; Patzig, Christian; Höche, Thomas

    2014-05-12

    We report on the experimental determination of the spontaneous polarization of wurtzite-(Mg,Zn)O by examination of the recombination dynamics of polar ZnO/(Mg,Zn)O quantum wells (QWs). The thickness-dependent decay time of the unscreened single-exciton states inside the QWs was modeled by a self-consistent solution of Schrödinger- and Poisson-equation to deduce the total polarization across the QW for different Mg-contents inside the barriers. By the separation of the piezoelectric components of the polarization, a linear increase in spontaneous polarization with increasing Mg-content x of P/x = (0.151 ± 0.015) C/m{sup 2} was determined for Mg{sub x} Zn{sub 1−x} O.

  4. Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chang-Yong Nam; Stein, Aaron; Kisslinger, Kim; Black, Charles T.

    2015-11-17

    We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ~1019 cm-3 carrier density, and ~0.1 cm2 V-1 s-1 electron mobility, reflecting highly nanocrystalline internal structure. The results demonstrate the potential application ofmore » infiltration synthesis in fabricating metal oxide electronic devices.« less

  5. Local structures of copper-doped ZnO films (Journal Article)...

    Office of Scientific and Technical Information (OSTI)

    Citation Details In-Document Search Title: Local structures of copper-doped ZnO films Authors: Ma, Q. ; Buchholz, D.B. ; Chang, R.P.H. 1 + Show Author Affiliations (NWU) ...

  6. Effects of Cr/Zn Substitutions on Dielectric Properties of CaCu{sub

    Office of Scientific and Technical Information (OSTI)

    3}Ti{sub 4}O{sub 12}(CCTO) Ceramics (Journal Article) | SciTech Connect Effects of Cr/Zn Substitutions on Dielectric Properties of CaCu{sub 3}Ti{sub 4}O{sub 12}(CCTO) Ceramics Citation Details In-Document Search Title: Effects of Cr/Zn Substitutions on Dielectric Properties of CaCu{sub 3}Ti{sub 4}O{sub 12}(CCTO) Ceramics Effects of Zn and Cr substitutions on dielectric properties of CaCu{sub 3-x}Zn{sub x}Ti{sub 4-y}Cr{sub y}O{sub 12} ceramics are reported. Dielectric measurements at room

  7. Structural Studies of Al:ZnO Powders and Thin Films | Stanford...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    the ZnO lattice, and measure its effect on the crystallinity of thin films prepared by sol-gel techniques, with an aim to understand how these properties affect the film...

  8. Synthesis of ZnO decorated graphene nanocomposite for enhanced photocatalytic properties

    SciTech Connect (OSTI)

    Gayathri, S.; Jayabal, P.; Kottaisamy, M.; Ramakrishnan, V.

    2014-05-07

    Zinc oxide/Graphene (GZ) composites with different concentrations of ZnO were successfully synthesized through simple chemical precipitation method. The X-ray diffraction pattern and the micro-Raman spectroscopic technique revealed the formation of GZ composite, and the energy dispersive X-ray spectrometry analysis showed the purity of the prepared samples. The ZnO nanoparticles decorated graphene sheets were clearly visible in the field emission scanning electron micrograph. Raman mapping was employed to analyze the homogeneity of the prepared samples. The diffuse-reflectance spectra clearly indicated that the formation of GZ composites promoted the absorption in the visible region also. The photocatalytic activity of ZnO and GZ composites was studied by the photodegradation of Methylene blue dye. The results revealed that the GZ composites exhibited a higher photocatalytic activity than pristine ZnO. Hence, we proposed a simple wet chemical method to synthesize GZ composite and its application on photocatalysis was demonstrated.

  9. Response-time improved hydrothermal-method-grown ZnO scintillator...

    Office of Scientific and Technical Information (OSTI)

    Response-time improved hydrothermal-method-grown ZnO scintillator for soft x-ray free-electron laser timing-observation Citation Details In-Document Search Title: Response-time...

  10. PEDOT-PSS coated ZnO/C hierarchical porous nanorods as ultralong...

    Office of Scientific and Technical Information (OSTI)

    PEDOT-PSS coated ZnOC hierarchical porous nanorods as ultralong-life anode material for lithium ion batteries This content will become publicly available on November 16, 2017 ...

  11. Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

    SciTech Connect (OSTI)

    Chang-Yong Nam; Stein, Aaron; Kisslinger, Kim; Black, Charles T.

    2015-11-17

    We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ~1019 cm-3 carrier density, and ~0.1 cm2 V-1 s-1 electron mobility, reflecting highly nanocrystalline internal structure. The results demonstrate the potential application of infiltration synthesis in fabricating metal oxide electronic devices.

  12. Luminescence and electrical properties of single ZnO/MgO core/shell nanowires

    SciTech Connect (OSTI)

    Grinblat, Gustavo; Comedi, David; Bern, Francis; Barzola-Quiquia, Jos; Esquinazi, Pablo; Tirado, Mnica

    2014-03-10

    To neutralise the influence of the surface of ZnO nanowires for photonics and optoelectronic applications, we have covered them with insulating MgO film and individually contacted them for electrical characterisation. We show that such a metal-insulator-semiconductor-type nanodevice exhibits a high diode ideality factor of 3.4 below 1?V. MgO shell passivates ZnO surface states and provides confining barriers to electrons and holes within the ZnO core, favouring excitonic ultraviolet radiative recombination, while suppressing defect-related luminescence in the visible and improving electrical conductivity. The results indicate the potential use of ZnO/MgO nanowires as a convenient building block for nano-optoelectronic devices.

  13. Single-valley quantum Hall ferromagnet in a dilute MgxZn1-xO/ZnO strongly correlated two-dimensional electron system

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kozuka, Y.; Tsukazaki, A.; Maryenko, D.; Falson, J.; Bell, C.; Kim, M.; Hikita, Y.; Hwang, H. Y.; Kawasaki, M.

    2012-02-03

    We investigate the spin susceptibility (g*m*) of dilute two-dimensional (2D) electrons confined at the MgxZn1-xO/ZnO heterointerface. Magnetotransport measurements show a four-fold enhancement of g*m*, dominated by the increase in the Landé g-factor. The g-factor enhancement leads to a ferromagnetic instability of the electron gas as evidenced by sharp resistance spikes. At high magnetic field, the large g*m* leads to full spin polarization, where we found sudden increase in resistance around the filling factors of half-integer, accompanied by complete disappearance of fractional quantum Hall (QH) states. Along with its large effective mass and the high electron mobility, our result indicates thatmore » the ZnO 2D system is ideal for investigating the effect of electron correlations in the QH regime.« less

  14. Ion-beam treatment to prepare surfaces of p-CdTe films

    DOE Patents [OSTI]

    Gessert, Timothy A.

    2001-01-01

    A method of making a low-resistance electrical contact between a p-CdTe layer and outer contact layers by ion beam processing comprising: a) placing a CdS/CdTe device into a chamber and evacuating the chamber; b) orienting the p-CdTe side of the CdS/CdTe layer so that it faces apparatus capable of generating Ar atoms and ions of preferred energy and directionality; c) introducing Ar and igniting the area of apparatus capable of generating Ar atoms and ions of preferred energy and directionality in a manner so that during ion exposure, the source-to-substrate distance is maintained such that it is less than the mean-free path or diffusion length of the Ar atoms and ions at the vacuum pressure; d) allowing exposure of the p-CdTe side of the device to said ion beam for a period less than about 5 minutes; and e) imparting movement to the substrate to control the real uniformity of the ion-beam exposure on the p-CdTe side of the device.

  15. Oxygen Incorporation During Fabrication of Substrate CdTe Photovoltaic Devices: Preprint

    SciTech Connect (OSTI)

    Duenow, J. N.; Dhere, R. G.; Kuciauskas, D.; Li, J. V.; Pankow, J. W.; DeHart, C. M.; Gessert, T. A.

    2012-06-01

    Recently, CdTe photovoltaic (PV) devices fabricated in the nonstandard substrate configuration have attracted increasing interest because of their potential compatibility with flexible substrates such as metal foils and polymer films. This compatibility could lead to the suitability of CdTe for roll-to-roll processing and building-integrated PV. Currently, however, the efficiencies of substrate CdTe devices reported in the literature are significantly lower ({approx}6%-8%) than those of high-performance superstrate devices ({approx}17%) because of significantly lower open-circuit voltage (Voc) and fill factor (FF). In our recent device development efforts, we have found that processing parameters required to fabricate high-efficiency substrate CdTe PV devices differ from those necessary for traditional superstrate CdTe devices. Here, we investigate how oxygen incorporation in the CdTe deposition, CdCl2 heat treatment, CdS deposition, and post-deposition heat treatment affect device characteristics through their effects on the junction. By adjusting whether oxygen is incorporated during these processing steps, we have achieved Voc values greater than 860 mV and efficiencies greater than 10%.

  16. Ligand-Mediated Modification of the Electronic Structure of CdSe Quantum Dots

    SciTech Connect (OSTI)

    Lee, Jonathan R.; Whitley, Heather D.; Meulenberg, Robert W.; Wolcott, Abraham; Zhang, Jin Z.; Prendergast, Peter; Lovingood, Derek D.; Strouse, Geoffrey F.; Ogitsu, Tadashi; Schwegler, Eric; Terminello, Louis J.; Van Buuren, Tony W.

    2012-05-18

    X-ray absorption spectroscopy and ab initio modeling of the experimental spectra have been used to investigate the effects of surface passivation on the unoccupied electronic states of CdSe quantum dots (QDs). Significant differences are observed in the unoccupied electronic structure of the CdSe QDs, which are shown to arise from variations in specific ligand-surface bonding interactions.

  17. Characterization of Aerosols Containing Zn, Pb, and Cl from an Industrial Region of Mexico City

    SciTech Connect (OSTI)

    Moffet, Ryan C.; Desyaterik, Yury; Hopkins, Rebecca J.; Tivanski, Alexei V.; Gilles, Marry K.; Wang, Yan A.; Shutthanandan, V.; Molina, Luisa T.; Abraham, Rodrigo G.; Johnson, Kirsten S.; Mugica, Violeta; Molina, Mario J.; Laskin, Alexander; Prather, Kimberly A.

    2008-10-01

    During the March, 2006 MILAGRO campaign, measurements in the Northern Mexico City Metropolitan Area revealed the frequent appearance of particles with a characteristically high content of internally mixed Zn, Pb, Cl, and P. A comprehensive study of the chemical and physical properties of these particles was performed using a complementary combination of aerosol measurement techniques. Individual particles were analyzed using Aerosol Time-of-Flight Mass Spectrometry (ATOFMS) and Computer Controlled Scanning Electron Microscopy/Energy Dispersive X-Ray spectroscopy (CCSEM/EDX). Proton Induced X-Ray Emission (PIXE) analysis of bulk aerosol samples provided time-resolved mass concentrations of individual elements. The PIXE measurements indicated that Zn is more strongly correlated with Cl than with any other element and that Zn concentrations are higher than other non-ferrous transition metals. The Zn- and Pb - containing particles have both spherical and non-spherical morphologies. Many metal rich particles had needle-like structures and were found to be composed of ZnO and/or Zn(NO3)2?6H2O as indicated by scanning transmission x-ray microscopy/near edge X-ray absorption spectroscopy (STXM/NEXAFS). The Zn and Pb rich particles were primarily in the submicron size range and internally mixed with elemental carbon. The unique chemical associations most closely match signatures acquired for garbage incineration. This unique combination of complementary analytical techniques has allowed for a comprehensive evaluation of Zn- and Pb- containing particles in a complex urban environment, highlighting unique characteristics that give powerful insight into their origin.

  18. Self-assembled ultra small ZnO nanocrystals for dye-sensitized solar cell application

    SciTech Connect (OSTI)

    Patra, Astam K.; Dutta, Arghya; Bhaumik, Asim

    2014-07-01

    We demonstrate a facile chemical approach to produce self-assembled ultra-small mesoporous zinc oxide nanocrystals using sodium salicylate (SS) as a template under hydrothermal conditions. These ZnO nanomaterials have been successfully fabricated as a photoanode for the dye-sensitized solar cell (DSSC) in the presence of N719 dye and iodinetriiodide electrolyte. The structural features, crystallinity, purity, mesophase and morphology of the nanostructure ZnO are investigated by several characterization tools. N{sub 2} sorption analysis revealed high surface areas (203 m{sup 2} g{sup ?1}) and narrow pore size distributions (5.15.4 nm) for different samples. The mesoporous structure and strong photoluminescence facilitates the high dye loading at the mesoscopic void spaces and light harvesting in DSSC. By utilizing this ultra-small ZnO photoelectrode with film thickness of about 7 ?m in the DSSC with an open-circuit voltage (V{sub OC}) of 0.74 V, short-circuit current density (J{sub SC}) of 3.83 mA cm{sup ?2} and an overall power conversion efficiency of 1.12% has been achieved. - Graphical abstract: Ultra-small ZnO nanocrystals have been synthesized with sodium salicylate as a template and using it as a photoanode in a dye-sensitized solar cell 1.12% power conversion efficiency has been observed. - Highlights: Synthesis of self-assembled ultra-small mesoporous ZnO nanocrystals by using sodium salicylate as a template. Mesoporous ZnO materials have high BET surface areas and void space. ZnO nanoparticles serve as a photoanode for the dye-sensitized solar cell (DSSC). Using ZnO nanocrystals as photoelectrode power conversion efficiency of 1.12% has been achieved.

  19. Piezoelectric and luminescent properties of ZnO nanostructures on Ag films.

    Office of Scientific and Technical Information (OSTI)

    (Conference) | SciTech Connect Conference: Piezoelectric and luminescent properties of ZnO nanostructures on Ag films. Citation Details In-Document Search Title: Piezoelectric and luminescent properties of ZnO nanostructures on Ag films. No abstract prepared. Authors: Tallant, David Robert ; Missert, Nancy A. ; Scrymgeour, David ; Voigt, James A. ; Liu, J. [1] ; Hsu, Julia, W. P. + Show Author Affiliations (.) Publication Date: 2006-11-01 OSTI Identifier: 898423 Report Number(s):

  20. Thin-film polycrystalline n-ZnO/p-CuO heterojunction

    SciTech Connect (OSTI)

    Lisitski, O. L.; Kumekov, M. E.; Kumekov, S. E. Terukov, E. I.

    2009-06-15

    Results of X-ray diffraction and spectral-optical studies of n-ZnO and p-CuO films deposited by gas-discharge sputtering with subsequent annealing are presented. It is shown that, despite the difference in the crystal systems, the polycrystallinity of n-ZnO and p-CuO films enables fabrication of a heterojunction from this pair of materials.

  1. Low-temperature aqueous-phase reforming of ethanol on bimetallic PdZn catalysts

    SciTech Connect (OSTI)

    Xiong, Haifeng; DelaRiva, Andrew; Wang, Yong; Dayte, Abhaya

    2015-01-01

    Bimetallic PdZn catalysts supported on carbon black (CB) and carbon nanotubes (CNTs) were found to be selective for CO-free H-2 production from ethanol at low temperature (250 degrees C). On Pd, the H-2 yield was low (similar to 0.3 mol H-2/mol ethanol reacted) and the CH4/CO2 ratio was high (similar to 1.7). Addition of Zn to Pd formed the intermetallic PdZn beta phase (atomic ratio of Zn to Pd is 1) with increased H-2 yield (similar to 1.9 mol H-2/mol ethanol reacted) and CH4/CO2 ratio of <1. The higher H-2 yield and low CH4 formation was related to the improved dehydrogenation activity of the L1(0) PdZn beta phase. The TOF increased with particle size and the CNTs provided the most active and selective catalysts, which may be ascribed to pore-confinement effects. Furthermore, no significant changes in either the supports or the PdZn beta particles was found after aqueous-phase reforming (APR) indicating that the metal nanoparticles and the carbon support are hydrothermally stable in the aqueous phase at elevated temperatures and pressures (>200 degrees C, 65 bar). No CO was detected for all the catalysts performed in aqueous-phase reaction, indicating that both monometallic Pd and bimetallic PdZn catalysts have high water-gas shift activity during APR. However, the yield of H-2 is considerably lower than the theoretical value of 6 H-2 per mole ethanol which is due to the presence of oxygenated products and methane on the PdZn catalysts.

  2. Zn speciation in a soil contaminated by the deposition of a dredged sediment by synchrotron X-ray techniques

    SciTech Connect (OSTI)

    Isaure, Marie-Pierre; Manceau, Alain; Laboudigue, Agnes; Tamura, Nobumichi; Marcus, Matthew A.

    2003-09-01

    The nature and proportion of Zn species present in an agricultural soil overlaid by a dredged contaminated sediment have been untangled by the novel combination of three non-invasive synchrotron-based x-ray techniques: x-ray microfluorescence ({mu}SXRF), microdiffraction ({mu}XRD), and absorption spectroscopy (EXAFS). One primary (franklinite) and two secondary (phyllomanganate and phyllosilicate) Zn-containing minerals were identified in the initial soil, and another primary (ZnS) and a new secondary (Fe-(oxyhydr)oxide) Zn species in the covered soil. The quantitative analysis of EXAFS spectra recorded on bulk samples indicated that ZnS and Zn-Fe (oxyhydr)oxides amounted to 71+-10 percent and 27+-10 percent, respectively, and the other Zn species to less than 10 percent. The two new Zn species found in the covered soil result from the gravitational migration of ZnS particles initially present in the sediment, and from their further oxidative dissolution and fixation of leached Zn on F e (oxyhydr) oxides.

  3. Determination of reactive oxygen species from ZnO micro-nano structures with shape-dependent photocatalytic activity

    SciTech Connect (OSTI)

    He, Weiwei; Zhao, Hongxiao; Jia, Huimin; Yin, Jun-Jie; Zheng, Zhi

    2014-05-01

    Graphical abstract: ZnO micro/nano structures with shape dependent photocatalytic activity were prepared by hydrothermal reaction. The generations of hydroxyl radical, superoxide and singlet oxygen from irradiated ZnO were identified precisely by electron spin resonance spectroscopy. The type of reactive oxygen species was determined by band gap structure of ZnO. - Highlights: ZnO micro/nano structures with different morphologies were prepared by solvothermal reaction. Multi-pod like ZnO structures exhibited superior photocatalytic activity. The generations of hydroxyl radical, superoxide and singlet oxygen from irradiated ZnO were characterized precisely by electron spin resonance spectroscopy. The type of reactive oxygen species was determined by band gap structure of ZnO. - Abstract: ZnO micro/nano structures with different morphologies have been prepared by the changing solvents used during their synthesis by solvothermal reaction. Three typical shapes of ZnO structures including hexagonal, bell bottom like and multi-pod formed and were characterized by scanning electron microscopy and X-ray diffraction. Multi pod like ZnO structures exhibited the highest photocatalytic activity toward degradation of methyl orange. Using electron spin resonance spectroscopy coupled with spin trapping techniques, we demonstrate an effective way to identify precisely the generation of hydroxyl radicals, superoxide and singlet oxygen from the irradiated ZnO multi pod structures. The type of reactive oxygen species formed was predictable from the band gap structure of ZnO. These results indicate that the shape of micro-nano structures significantly affects the photocatalytic activity of ZnO, and demonstrate the value of electron spin resonance spectroscopy for characterizing the type of reactive oxygen species formed during photoexcitation of semiconductors.

  4. A novel investigation on carbon nanotube/ZnO, Ag/ZnO and Ag/carbon nanotube/ZnO nanowires junctions for harvesting piezoelectric potential on textile

    SciTech Connect (OSTI)

    Khan, Azam Edberg, Jesper; Nur, Omer; Willander, Magnus

    2014-07-21

    In the present work, three junctions were fabricated on textile fabric as an alternative substrate for harvesting piezoelectric potential. First junction was formed on ordinary textile as (textile/multi-walled carbon nanotube film/zinc oxide nanowires (S1: T/CNTs/ZnO NWs)) and the other two were formed on conductive textile with the following layer sequence: conductive textile/zinc oxide nanowires (S2: CT/ZnO NWs) and conductive textile/multi-walled carbon nanotubes film/zinc oxide nanowires (S3: CT/CNTs/ZnO NWs). Piezoelectric potential was harvested by using atomic force microscopy in contact mode for the comparative analysis of the generated piezoelectric potential. ZnO NWs were synthesized by using the aqueous chemical growth method. Surface analysis of the grown nanostructures was performed by using scanning electron microscopy and transmission electron microscopy. The growth orientation and crystalline size were studied by using X-ray diffraction technique. This study reveals that textile as an alternative substrate have many features like cost effective, highly flexible, nontoxic, light weight, soft, recyclable, reproducible, portable, wearable, and washable for nanogenerators fabrication with acceptable performance and with a wide choice of modification for obtaining large amount of piezoelectric potential.

  5. Facile combustion synthesis of ZnO nanoparticles using Cajanus cajan (L.) and its multidisciplinary applications

    SciTech Connect (OSTI)

    Manjunath, K.; Ravishankar, T.N.; Kumar, Dhanith; Priyanka, K.P; Varghese, Thomas; Naika, H.Raja; Nagabhushana, H.; Sharma, S.C.; Dupont, J.; Ramakrishnappa, T.; Nagaraju, G.

    2014-09-15

    Graphical abstract: Facile combustion synthesis of ZnO nanoparticles using Cajanuscajan (L.) and its multidisciplinary applications.Zinc oxide nanoparticles were successfully synthesized by solution combustion method (SCM) using pigeon pea as a combustible fuel for the first time. The as-prepared product shows good photocatalytic, dielectric, antibacterial, electrochemical properties. - Highlights: • ZnO Nps were synthesized via combustion method using pigeon pea as a fuel. • The structure of the product was confirmed by XRD technique. • The morphology was confirmed by SEM and TEM images. • The as-prepared product shown good photocatalytic activity, dielectric property. • It has also shown good antibacterial and electrochemical properties. - Abstract: Zinc oxide nanoparticles (ZnO Nps) were successfully synthesized by solution combustion method (SCM) using pigeon pea as a fuel for the first time. X-Ray diffraction pattern reveals that the product belongs to hexagonal system. FTIR spectrum of ZnO Nps shows the band at 420 cm{sup −1} associated with the characteristic vibration of Zn–O. TEM images show that the nanoparticles are found to be ∼40–80 nm. Furthermore, the as-prepared ZnO Nps exhibits good photocatalytic activity for the photodegradation of methylene blue (MB), indicating that they are indeed a promising photocatalytic semiconductor. The antibacterial properties of ZnO nanopowders were investigated by their bactericidal activity against four bacterial strains.

  6. Platelets to rings: Influence of sodium dodecyl sulfate on Zn-Al layered double hydroxide morphology

    SciTech Connect (OSTI)

    Yilmaz, Ceren; Unal, Ugur; Yagci Acar, Havva

    2012-03-15

    In the current study, influence of sodium dodecyl sulfate (SDS) on the crystallization of Zn-Al layered double hydroxide (LDH) was investigated. Depending on the SDS concentration coral-like and for the first time ring-like morphologies were obtained in a urea-hydrolysis method. It was revealed that the surfactant level in the starting solution plays an important role in the morphology. Concentration of surfactant equal to or above the anion exchange capacity of the LDH is influential in creating different morphologies. Another important parameter was the critical micelle concentration (CMC) of the surfactant. Surfactant concentrations well above CMC value resulted in ring-like structures. The crystallization mechanism was discussed. - Graphical abstract: Dependence of ZnAl LDH Morphology on SDS concentration. Highlights: Black-Right-Pointing-Pointer In-situ intercalation of SDS in ZnAl LDH was achieved via urea hydrolysis method. Black-Right-Pointing-Pointer Morphology of ZnAl LDH intercalated with SDS depended on the SDS concentration. Black-Right-Pointing-Pointer Ring like morphology for SDS intercalated ZnAl LDH was obtained for the first time. Black-Right-Pointing-Pointer Growth mechanism was discussed. Black-Right-Pointing-Pointer Template assisted growth of ZnAl LDH was proposed.

  7. Hydroquinone-ZnO nano-laminate deposited by molecular-atomic layer deposition

    SciTech Connect (OSTI)

    Huang, Jie; Lucero, Antonio T.; Cheng, Lanxia; Kim, Jiyoung; Hwang, Hyeon Jun; Ha, Min-Woo

    2015-03-23

    In this study, we have deposited organic-inorganic hybrid semiconducting hydroquinone (HQ)/zinc oxide (ZnO) superlattices using molecular-atomic layer deposition, which enables accurate control of film thickness, excellent uniformity, and sharp interfaces at a low deposition temperature (150 °C). Self-limiting growth of organic layers is observed for the HQ precursor on ZnO surface. Nano-laminates were prepared by varying the number of HQ to ZnO cycles in order to investigate the physical and electrical effects of different HQ to ZnO ratios. It is indicated that the addition of HQ layer results in enhanced mobility and reduced carrier concentration. The highest Hall mobility of approximately 2.3 cm{sup 2}/V·s and the lowest n-type carrier concentration of approximately 1.0 × 10{sup 18}/cm{sup 3} were achieved with the organic-inorganic superlattice deposited with a ratio of 10 ZnO cycles to 1 HQ cycle. This study offers an approach to tune the electrical transport characteristics of ALD ZnO matrix thin films using an organic dopant. Moreover, with organic embedment, this nano-laminate material may be useful for flexible electronics.

  8. Ferromagnetism in Gd doped ZnO nanowires: A first principles study

    SciTech Connect (OSTI)

    Aravindh, S. Assa; Schwingenschloegl, Udo E-mail: iman.roqan@kaust.edu.sa; Roqan, Iman S. E-mail: iman.roqan@kaust.edu.sa

    2014-12-21

    In several experimental studies, room temperature ferromagnetism in Gd-doped ZnO nanostructures has been achieved. However, the mechanism and the origin of the ferromagnetism remain controversial. We investigate the structural, magnetic, and electronic properties of Zn{sub 48}O{sub 48} nanowires doped with Gd, using density functional theory. Our findings indicate that substitutionally incorporated Gd atoms prefer occupying the surface Zn sites. Moreover, the formation energy increases with the distance between Gd atoms, signifying that no Gd-Gd segregation occurs in the nanowires within the concentration limit of ?2%. Gd induces ferromagnetism in ZnO nanowires with magnetic coupling energy up to 21?meV in the neutral state, which increases with additional electron and O vacancy, revealing the role of carriers in magnetic exchange. The potential for achieving room temperature ferromagnetism and high T{sub C} in ZnO:Gd nanowires is evident from the large ferromagnetic coupling energy (200?meV) obtained with the O vacancy. Density of states shows that Fermi level overlaps with Gd f states with the introduction of O vacancy, indicating the possibility of s-f coupling. These results will assist in understanding experimental findings in Gd-doped ZnO nanowires.

  9. Nucleation and growth of ZnO on PMMA by low-temperature atomic layer deposition

    SciTech Connect (OSTI)

    Napari, Mari Malm, Jari; Lehto, Roope; Julin, Jaakko; Arstila, Kai; Sajavaara, Timo; Lahtinen, Manu

    2015-01-15

    ZnO films were grown by atomic layer deposition at 35?C on poly(methyl methacrylate) substrates using diethylzinc and water precursors. The film growth, morphology, and crystallinity were studied using Rutherford backscattering spectrometry, time-of-flight elastic recoil detection analysis, atomic force microscopy, scanning electron microscopy, and x-ray diffraction. The uniform film growth was reached after several hundreds of deposition cycles, preceded by the precursor penetration into the porous bulk and island-type growth. After the full surface coverage, the ZnO films were stoichiometric, and consisted of large grains (diameter 30?nm) with a film surface roughness up to 6?nm (RMS). The introduction of Al{sub 2}O{sub 3} seed layer enhanced the initial ZnO growth substantially and changed the surface morphology as well as the crystallinity of the deposited ZnO films. Furthermore, the water contact angles of the ZnO films were measured, and upon ultraviolet illumination, the ZnO films on all the substrates became hydrophilic, independent of the film crystallinity.

  10. Effects of Zn additions to highly magnetoelastic FeGa alloys

    SciTech Connect (OSTI)

    Lograsso, Thomas A.; Jones, Nicholas J.; Wun-Fogle, Marilyn; Restorff, James B.; Schlagel, Deborah L.; Petculescu, Gabriela; Clark, Arthur E.; Hathaway, Kristl B.

    2015-05-07

    Fe{sub 1−x}M{sub x} (M = Ga, Ge, Si, Al, Mo and x ∼ 0.18) alloys offer an extraordinary combination of magnetoelasticity and mechanical properties. They are rare-earth-free, can be processed using conventional deformation techniques, have high magnetic permeability, low hysteresis, and low magnetic saturation fields, making them attractive for device applications such as actuators and energy harvesters. Starting with Fe-Ga as a reference and using a rigid-band-filling argument, Zhang et al. predicted that lowering the Fermi level by reducing the total number of electrons could enhance magnetoelasticity. To provide a direct experimental validation for Zhang's hypothesis, elemental additions with lower-than-Ga valence are needed. Of the possible candidates, only Be and Zn have sufficient solubility. Single crystals of bcc Fe-Ga-Zn have been grown with up to 4.6 at. % Zn in a Bridgman furnace under elevated pressure (15 bars) in order to overcome the high vapor pressure of Zn and obtain homogeneous crystals. Single-crystal measurements of magnetostriction and elastic constants allow for the direct comparison of the magnetoelastic coupling constants of Fe-Ga-Zn with those of other magnetoelastic alloys in its class. The partial substitution of Ga with Zn yields values for the magnetoelastic coupling factor, −b{sub 1}, comparable to those of the binary Fe-Ga alloy.

  11. Growth of CdTe thin films on graphene by close-spaced sublimation method

    SciTech Connect (OSTI)

    Jung, Younghun; Yang, Gwangseok; Kim, Jihyun, E-mail: hyunhyun7@korea.ac.kr [Department of Chemical and Biological Engineering, Korea University, Seoul 136-701 (Korea, Republic of)] [Department of Chemical and Biological Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Chun, Seungju; Kim, Donghwan [Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of)] [Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of)

    2013-12-02

    CdTe thin films grown on bi-layer graphene were demonstrated by using the close-spaced sublimation method, where CdTe was selectively grown on the graphene. The density of the CdTe domains was increased with increasing the number of the defective sites in the graphene, which was controlled by the duration of UV exposure. The CdTe growth rate on the bi-layer graphene electrodes was 400?nm/min with a bandgap energy of 1.451.49?eV. Scanning electron microscopy, micro-Raman spectroscopy, micro-photoluminescence, and X-ray diffraction technique were used to confirm the high quality of the CdTe thin films grown on the graphene electrodes.

  12. Surface Plasmon Excitation via Au Nanoparticles in CdSe Semiconductor

    SciTech Connect (OSTI)

    Pradhan, A. K.; Konda, R. B.; Mundle, R.; Mustafa, H.; Bamiduro, O.; Roy, U. N.; Cui, Y.; Burger, A.

    2008-10-23

    We present experimental evidence for the large Raman and photoluminescence enhancement in CdSe semiconductor films grown on Si and glass substrates due to excitation of surface plasmon resonances in proximate gold metal nanoparticles deposited on the surface of CdSe film. Heterojunction diodes containing n-CdSe on p-Si semiconductor were fabricated and the surface of the diodes was in situ coated with Au nanoparticles using the ultra-high vacuum pulsed-laser deposition technique. A significant enhancement of the photocurrent was obtained in CdSe/p-Si containing Au nanoparticles on the surface compared to CdSe/p-Si due to the enhanced photo-absorption within the semiconductor by the phenomenon of surface plasmon resonance. These observations suggest a variety of approaches for improving the performance of devices such as photodetectors, photovoltaic, and related devices, including biosensors.

  13. Charge transfer and mobility enhancement at CdO/SnTe heterointerfaces

    SciTech Connect (OSTI)

    Nishitani, Junichi; Yu, Kin Man; Walukiewicz, Wladek

    2014-09-29

    We report a study of the effects of charge transfer on electrical properties of CdO/SnTe heterostructures. A series of structures with variable SnTe thicknesses were deposited by RF magnetron sputtering. Because of an extreme type III band offset with the valence band edge of SnTe located at 1.5?eV above the conduction band edge of CdO, a large charge transfer is expected at the interface of the CdO/SnTe heterostructure. The electrical properties of the heterostructures are analyzed using a multilayer charge transport model. The analysis indicates a large 4-fold enhancement of the CdO electron mobility at the interface with SnTe. The mobility enhancement is attributed to reduction of the charge center scattering through neutralization of the donor-like defects responsible for the Fermi level pinning at the CdO/SnTe interface.

  14. The structural, electrical, and optical properties of hydrogenated chromium-doped CdO films

    SciTech Connect (OSTI)

    Dakhel, A.A.; Hamad, H.

    2013-12-15

    Cadmium oxide thin films doped with different amounts of chromium and annealed in hydrogen atmosphere have been grown on glass substrates by means of physical vapour deposition (PVD) method. The structural, electrical, and optical properties of the prepared Cr-doped CdO (CdO:Cr–H) films were systematically studied. The structural investigations show that the incorporated Cr ions mainly occupied locations in interstitial positions of CdO lattice. The bandgap engineer by Cr incorporation and hydrogenation were studied. The variations of the electrical parameters of CdO:Cr–H films with Cr incorporation and hydrogenation were investigated. It was established that among the investigated samples, the largest mobility and conductivity were measured with 1.5%:Cr–H film. Therefore, hydrogenated CdO:Cr films can be effectively used in different applications of near infrared-transparent-conducting-oxide (NIR-TCO). - Graphical abstract: Optoelectronic properties of synthesised chromium-doped CdO thin films. It was established that the largest mobility (53.4 cm{sup 2}/V.s) and conductivity (2136.8 S/cm) were measured in 1.5%:Cr–H doped CdO film. Therefore, such films can be effectively used in near infrared-transparent-conducting-oxide (NIR-TCO). - Highlights: • The properties of CdO films annealed in H{sub 2} gas were systematically studied. • Cr{sup 3+} ions most likely occupied interstitial locations in CdO lattice and as donors. • Improvement of conductivity parameters with Cr doping and H annealing. • Bandgap narrowing observed with Cd-doping.

  15. Optical injection probing of single ZnO tetrapod lasers

    SciTech Connect (OSTI)

    Szarko, Jodi M.; Song, Jae Kyu; Blackledge, Charles Wesley; Swart, Ingmar; Leone, Stephen R.; Li, Shihong; Zhao, Yiping

    2004-11-23

    The properties of zinc oxide (ZnO) nanotetrapod lasers are characterized by a novel ultrafast two-color pump/stimulated emission probe technique. Single legs of tetrapod species are isolated by a microscope objective, pumped by 267 nm pulses, and subjected to a time-delayed 400 nm optical injection pulse, which permits investigation of the ultrafast carrier dynamics in the nanosize materials. With the optical injection pulse included, a large increase in the stimulated emission at 400 nm occurs, which partially depletes the carriers at this wavelength and competes with the normal 390 nm lasing. At the 390 nm lasing wavelengths, the optical injection causes a decrease in the stimulated emission due to the energetic redistribution of the excited carrier depletion, which occurs considerably within the time scale of the subpicosecond duration of the injection pulse. The effects of the optical injection on the spectral gain are employed to probe the lasing dynamics, which shows that the full width at half maximum of the lasing time is 3 ps.

  16. LiF/ZnS Neutron Multiplicity Counter

    SciTech Connect (OSTI)

    Stave, Sean C.; Bliss, Mary; Kouzes, Richard T.; Lintereur, Azaree T.; Robinson, Sean M.; Siciliano, Edward R.; Wood, Lynn S.

    2015-06-01

    Abstract: Alternatives to the use of 3He for the detection of thermal neutrons are being investigated. One of the most challenging applications for 3He alternatives is in neutron multiplicity counters. Neutron multiplicity counters are used to provide rapid assay of samples which contain an unknown amount of plutonium in a potentially unknown configuration. With appropriate detector design, the neutron single, double, and triple coincidence events can be used to extract information of three unknown parameters such as the 240Pu-effective mass, the sample self-multiplication, and the (α,n) rate. A project at PNNL has investigated replacing 3He-based tubes with LiF/ZnS neutron-scintillator sheets and wavelength shifting plastic for light pipes. A four-panel demonstrator module has been constructed, tested, and compared with detailed modeling results. The findings indicate that a full-scale system can be constructed with the same overall size as the most efficient 3He-based system and with improved performance. Remaining design challenges include electronics and robust neutron/gamma-ray discrimination based on pulse shape analysis at high rates. A review of the current effort and the most recent findings will be presented.

  17. Doping of ZnO nanowires using phosphorus diffusion from a spin-on doped glass source

    SciTech Connect (OSTI)

    Bocheux, A.; Robin, I. C.; Bonaimé, J.; Hyot, B.; Feuillet, G.; Kolobov, A. V.; Fons, P.; Mitrofanov, K. V.; Tominaga, J.; Tamenori, Y.

    2014-05-21

    In this article, we report on ZnO nanowires that were phosphorus doped using a spin on dopant glass deposition and diffusion method. Photoluminescence measurements suggest that this process yields p-doped ZnO. The spatial location of P atoms was studied using x-ray near-edge absorption structure spectroscopy and it is concluded that the doping is amphoteric with P atoms located on both Zn and O sites.

  18. Characterization of nanocrystalline ZnO:Al films by sol-gel spin coating method

    SciTech Connect (OSTI)

    Gareso, P. L. Rauf, N. Juarlin, E.; Sugianto,; Maddu, A.

    2014-09-25

    Nanocrystalline ZnO films doped with aluminium by sol-gel spin coating method have been investigated using optical transmittance UV-Vis and X-ray diffraction (X-RD) measurements. ZnO films were prepared using zinc acetate dehydrate (Zn(CH{sub 3}COO){sub 2}@@2H{sub 2}O), ethanol, and diethanolamine (DEA) as a starting material, solvent, and stabilizer, respectively. For doped films, AlCl{sub 3} was added to the mixture. The ZnO:Al films were deposited on a transparent conductive oxide (TCO) substrate using spin coating technique at room temperature with a rate of 3000 rpm in 30 sec. The deposited films were annealed at various temperatures from 400C to 600C during 60 minutes. The transmittance UV-Vis measurement results showed that after annealing at 400C, the energy band gap profile of nanocrystalline ZnO:Al film was a blue shift. This indicated that the band gap of ZnO:Al increased after annealing due to the increase of crystalline size. As the annealing temperature increased the bandgap energy was a constant. In addition to this, there was a small oscillation occurring after annealing compared to the asgrown samples. In the case of X-RD measurements, the crystalinity of the films were amorphous before annealing, and after annealing the crystalinity became enhance. Also, X-RD results showed that structure of nanocrystalline ZnO:Al films were hexagonal polycrystalline with lattice parameters are a = 3.290 and c = 5.2531 .

  19. The Investigation of Decomposition of Supersaturated Si<Zn> Solid Solution by X-Ray Diffuse Scattering

    SciTech Connect (OSTI)

    Shcherbachev, Kirill; Privezentsev, Vladimir

    2010-04-06

    The results of investigation of microstructure of Zn doped n-type Si by X-ray Diffuse Scattering (XRDS) are presented. Experimental samples were made by a high-temperature Zn diffusion annealing with subsequent quenching and tempering. Reciprocal space maps of XRDS were obtained. They resulted in that crystal lattice of the samples contains spherical MDs of vacancy type and plane shape MDs of interstitial type. The MDs average radius and their type depend on Zn doping level and thermal treatment after Zn diffusion.

  20. The effect of Ce{sup 4+} incorporation on structural, morphological and photocatalytic characters of ZnO nanoparticles

    SciTech Connect (OSTI)

    Kannadasan, N.; Shanmugam, N. Cholan, S.; Sathishkumar, K.; Viruthagiri, G.; Poonguzhali, R.

    2014-11-15

    We report a simple chemical precipitation method for the preparation of undoped and cerium doped ZnO nanocrystals. The concentration of cerium in the products can be controlled in the range of 0.0250.125 mol. The structure and chemical compositions of the products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy; energy dispersive spectrum and Fourier transform infrared spectroscopy. The results demonstrate that Ce{sup 4+} ions were successfully incorporated into the lattice position of Zn{sup 2+} ions in ZnO. The morphology of the products was analyzed by field emission scanning electron microscopy and confirmed by high resolution transmission electron microscope analysis. The optical properties of the products were studied by ultravioletvisible and room temperature photoluminescence measurements. The photoluminescence emission spectra of Ce-doped ZnO showed enhanced visible emissions as a result of 5d ? 4f transition of cerium. In particular, a novel photocatalytic activity of the products was assessed using methylene blue. The obtained result reveals that Ce-doped products show higher reduction efficiency for methylene blue than the undoped ZnO. - Highlights: Nanocrystals of ZnO and ZnO:Ce{sup 4+} were grown. XPS results confirmed the incorporated cerium in tetravalence. PL emission exhibited 5d ? 4f transition on cerium doping. Doped ZnO decolorizes MB faster than undoped ZnO.

  1. La-doped ZnO nanoparticles: Simple solution-combusting preparation and applications in the wastewater treatment

    SciTech Connect (OSTI)

    Wu, Tingting; Ni, Yonghong; Ma, Xiang; Hong, Jianming

    2013-11-15

    Graphical abstract: La-doped ZnO nanoparticles have been successfully prepared by a simple solution combustion route and exhibit good adsorption for Cu and Pb ion from water systems. - Highlights: • La-doped ZnO nanoparticles were successfully prepared via a simple solution-combustion route. • The integration of La{sup 3+} ions into ZnO decreased the band-gap of ZnO nanoparticles. • La-doped ZnO nanoparticles could remove more Pb and Cu ions from water resources than undoped ZnO. - Abstract: La-doped ZnO nanoparticles have been successfully synthesized by a simple solution combustion method via employing a mixture of ethanol and ethyleneglycol (v/v = 60/40) as the solvent. Zinc acetate and oxygen gas in the atmosphere were used as zinc and oxygen sources, and La(NO{sub 3}){sub 3} as the doping reagent. The as-obtained product was characterized by means of powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectrometry and X-ray photoelectron spectroscopy. Experiments showed that La-doped ZnO nanoparticles exhibited the higher capacities for the removal of Pb{sup 2+} and Cu{sup 2+} ions in water resource than undoped ZnO nanoparticles.

  2. Development of vertically aligned ZnO-nanowires scintillators for high spatial resolution x-ray imaging

    SciTech Connect (OSTI)

    Kobayashi, Masakazu Komori, Jun; Shimidzu, Kaiji; Izaki, Masanobu; Uesugi, Kentaro; Takeuchi, Akihisa; Suzuki, Yoshio

    2015-02-23

    Newly designed scintillator of (0001)-oriented ZnO vertical nanowires (vnws) for X-ray imaging was prepared on a Ga-doped ZnO/soda-lime glass by electrodeposition, and the light emission feature was estimated in a synchrotron radiation facility. The ZnO-vnws scintillator revealed a strong light emission and improved resolution on CMOS image compared with that for the ZnO-layer scintillator, although the light emission performance was deteriorated in comparison to the Lu{sub 3}Al{sub 5}O{sub 12:}Ce{sup 3+}. The light emission property closely related to the nanostructure and the resultant photoluminescence characteristic.

  3. Copper doping of ZnO crystals by transmutation of {sup 64}Zn to {sup 65}Cu: An electron paramagnetic resonance and gamma spectroscopy study

    SciTech Connect (OSTI)

    Recker, M. C.; McClory, J. W. Holston, M. S.; Golden, E. M.; Giles, N. C.; Halliburton, L. E.

    2014-06-28

    Transmutation of {sup 64}Zn to {sup 65}Cu has been observed in a ZnO crystal irradiated with neutrons. The crystal was characterized with electron paramagnetic resonance (EPR) before and after the irradiation and with gamma spectroscopy after the irradiation. Major features in the gamma spectrum of the neutron-irradiated crystal included the primary 1115.5 keV gamma ray from the {sup 65}Zn decay and the positron annihilation peak at 511 keV. Their presence confirmed the successful transmutation of {sup 64}Zn nuclei to {sup 65}Cu. Additional direct evidence for transmutation was obtained from the EPR of Cu{sup 2+} ions (where {sup 63}Cu and {sup 65}Cu hyperfine lines are easily resolved). A spectrum from isolated Cu{sup 2+} (3d{sup 9}) ions acquired after the neutron irradiation showed only hyperfine lines from {sup 65}Cu nuclei. The absence of {sup 63}Cu lines in this Cu{sup 2+} spectrum left no doubt that the observed {sup 65}Cu signals were due to transmuted {sup 65}Cu nuclei created as a result of the neutron irradiation. Small concentrations of copper, in the form of Cu{sup +}-H complexes, were inadvertently present in our as-grown ZnO crystal. These Cu{sup +}-H complexes are not affected by the neutron irradiation, but they dissociate when a crystal is heated to 900 °C. This behavior allowed EPR to distinguish between the copper initially in the crystal and the copper subsequently produced by the neutron irradiation. In addition to transmutation, a second major effect of the neutron irradiation was the formation of zinc and oxygen vacancies by displacement. These vacancies were observed with EPR.

  4. Chapter 1.19: Cadmium Telluride Photovoltaic Thin Film: CdTe

    SciTech Connect (OSTI)

    Gessert, T. A.

    2012-01-01

    The chapter reviews the history, development, and present processes used to fabricate thin-film, CdTe-based photovoltaic (PV) devices. It is intended for readers who are generally familiar with the operation and material aspects of PV devices but desire a deeper understanding of the process sequences used in CdTe PV technology. The discussion identifies why certain processes may have commercial production advantages and how the various process steps can interact with each other to affect device performance and reliability. The chapter concludes with a discussion of considerations of large-area CdTe PV deployment including issues related to material availability and energy-payback time.

  5. Graphene/CdTe heterostructure solar cell and its enhancement with photo-induced doping

    SciTech Connect (OSTI)

    Lin, Shisheng Chen, Hongsheng; Li, Xiaoqiang; Zhang, Shengjiao; Wang, Peng; Xu, Zhijuan; Zhong, Huikai; Wu, Zhiqian

    2015-11-09

    We report a type of solar cell based on graphene/CdTe Schottky heterostructure, which can be improved by surface engineering as graphene is atomic thin. By coating a layer of ultrathin CdSe quantum dots onto graphene/CdTe heterostructure, the power conversion efficiency is increased from 2.08% to 3.10%. Photo-induced doping is mainly accounted for this enhancement, as evidenced by field effect transport, Raman, photoluminescence, and quantum efficiency measurements. This work demonstrates a feasible way of improving the performance of graphene/semiconductor heterostructure solar cells by combining one dimensional with two dimensional materials.

  6. Synthesis of CdS nanoparticles for photocatalytic application of methyleneblue degradation

    SciTech Connect (OSTI)

    Muthuraj, V.; Umadevi, M.; Sankarasubramanian, K.; Kajamuhideen, M. S.

    2014-04-24

    CdS nanoparticles were prepared by the reaction of cadmium acetate with thiourea in the presence and absence of methylene blue dye (MB). The nanoparticles were characterized by, XRD, FT-IR, UV-Vis. XRD study shows the presence of hexagonal phase for the nanoparticles whereas in case of the bulk samples only the hexagonal phase is observed. Fourier transform infrared spectroscopy (FT-IR) showed a strong interaction of methyl groups with CdS nanoparticles. The degradation of methylene blue was analysed using UV-Vis absorbance spectrum. Thus the results authenticate that methylene blue dye influences the structural and optical properties of the CdS nanoparticles.

  7. An oleic acid-capped CdSe quantum-dot sensitized solar cell

    SciTech Connect (OSTI)

    Chen Jing; Song, J. L.; Deng, W. Q.; Sun, X. W.; Jiang, C. Y.; Lei, W.; Huang, J. H.; Liu, R. S.

    2009-04-13

    In this letter, we report an oleic acid (OA)-capped CdSe quantum-dot sensitized solar cell (QDSSC) with an improved performance. The TiO{sub 2}/OA-CdSe photoanode in a two-electrode device exhibited a photon-to-current conversion efficiency of 17.5% at 400 nm. At AM1.5G irradiation with 100 mW/cm{sup 2} light intensity, the QDSSCs based on OA-capped CdSe showed a power conversion efficiency of about 1%. The function of OA was to increase QD loading, extend the absorption range and possibly suppress the surface recombination.

  8. DOE CD-3b Review of the MINERvA Project

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    3b Review of the MINERvA Project Main INjector ExpeRiment v-A August 21, 2007 | Overview | CD-3b Documentation| Other Documents| Overview of Charge and Experiment MINERvA Overview (pdf) Review Agenda (pdf) Review Charge (pdf) DOE CD-3b Scorecard (pdf with links) Scorecard Addendum describing documents not needed by MINERvA for CD-3b (pdf with links) Review Presentations by MINERvA Project Team (links to appear the week of August 14) Project Overview (pdf) Scintillators (WBS 1.0) WLS Fibers (WBS

  9. Synthesis and Characterization of PhotocatalyticTiO2-ZnFe2O4Nanoparticles

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Srinivasan, Sesha S.; Wade, Jeremy; Stefanakos, Elias K.

    2006-01-01

    A new coprecipitation/hydrolysis synthesis route is used to create aTiO2-ZnFe2O4nanocomposite that is directed towards extending the photoresponse ofTiO2from UV to visible wavelengths (>400?nm). The effect ofTiO2's accelerated anatase-rutile phase transformation due to the presence of the coupledZnFe2O4narrow-bandgap semiconductor is evaluated. The transformation's dependence on pH, calcinations temperature, particle size, andZnFe2O4concentration has been analyzed using XRD, SEM, and UV-visible spectrometry. The requirements for retaining the highly photoactive anatase phase present in aZnFe2O4nanocomposite are outlined. The visible-light-activated photocatalytic activity of theTiO2-ZnFe2O4nanocomposites has been compared to an AldrichTiO2reference catalyst, using a solar-simulated photoreactor formorethe degradation of phenol.less

  10. Synthesis and Characterization of Photocatalytic TiO 2 -ZnFe 2 O 4 Nanoparticles

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Srinivasan, Sesha S.; Wade, Jeremy; Stefanakos, Elias K.

    2006-01-01

    A new coprecipimore » tation/hydrolysis synthesis route is used to create a TiO 2 -ZnFe 2 O 4 nanocomposite that is directed towards extending the photoresponse of TiO 2 from UV to visible wavelengths ( > 400   nm ). The effect of TiO 2 's accelerated anatase-rutile phase transformation due to the presence of the coupled ZnFe 2 O 4 narrow-bandgap semiconductor is evaluated. The transformation's dependence on pH, calcinations temperature, particle size, and ZnFe 2 O 4 concentration has been analyzed using XRD, SEM, and UV-visible spectrometry. The requirements for retaining the highly photoactive anatase phase present in a ZnFe 2 O 4 nanocomposite are outlined. The visible-light-activated photocatalytic activity of the TiO 2 -ZnFe 2 O 4 nanocomposites has been compared to an Aldrich TiO 2 reference catalyst, using a solar-simulated photoreactor for the degradation of phenol.« less

  11. Defects in paramagnetic Co-doped ZnO films studied by transmission electron microscopy

    SciTech Connect (OSTI)

    Kovcs, A.; Duchamp, M.; Boothroyd, C. B.; Dunin-Borkowski, R. E.; Ney, A.; Ney, V.; Galindo, P. L.; Kaspar, T. C.; Chambers, S. A.

    2013-12-28

    We study planar defects in epitaxial Co:ZnO dilute magnetic semiconductor thin films deposited on c-plane sapphire (Al{sub 2}O{sub 3}), as well as the Co:ZnO/Al{sub 2}O{sub 3} interface, using aberration-corrected transmission electron microscopy and electron energy-loss spectroscopy. Co:ZnO samples that were deposited using pulsed laser deposition and reactive magnetron sputtering are both found to contain extrinsic stacking faults, incoherent interface structures, and compositional variations within the first 34 Co:ZnO layers next to the Al{sub 2}O{sub 3} substrate. The stacking fault density is in the range of 10{sup 17} cm{sup ?3}. We also measure the local lattice distortions around the stacking faults. It is shown that despite the relatively high density of planar defects, lattice distortions, and small compositional variation, the Co:ZnO films retain paramagnetic properties.

  12. Enhanced piezoelectric output voltage and Ohmic behavior in Cr-doped ZnO nanorods

    SciTech Connect (OSTI)

    Sinha, Nidhi; Ray, Geeta; Godara, Sanjay; Gupta, Manoj K.; Kumar, Binay

    2014-11-15

    Highlights: • Low cost highly crystalline Cr-doped ZnO nanorods were synthesized. • Enhancement in dielectric, piezoelectric and ferroelectric properties were observed. • A high output voltage was obtained in AFM. • Cr-doping resulted in enhanced conductivity and better Ohmic behavior in ZnO/Ag contact. - Abstract: Highly crystalline Cr-doped ZnO nanorods (NRs) were synthesized by solution technique. The size distribution was analyzed by high resolution tunneling electron microscope (HRTEM) and particle size analyzer. In atomic force microscope (AFM) studies, peak to peak 8 mV output voltage was obtained on the application of constant normal force of 25 nN. It showed high dielectric constant (980) with phase transition at 69 °C. Polarization vs. electric field (P–E) loops with remnant polarization (6.18 μC/cm{sup 2}) and coercive field (0.96 kV/cm) were obtained. In I–V studies, Cr-doping was found to reduce the rectifying behavior in the Ag/ZnO Schottky contact which is useful for field effect transistor (FET) and solar cell applications. With these excellent properties, Cr-doped ZnO NRs can be used in nanopiezoelectronics, charge storage and ferroelectric applications.

  13. Synthesis of Uniformly Distributed Single- and Double-sided Zinc Oxide (ZnO) Nanocombs

    SciTech Connect (OSTI)

    Petford-Long, Amanda K.; Liu, Yuzi; Altintas Yildirim, Ozlem

    2015-11-15

    Uniformly distributed single- and double-sided zinc oxide (ZnO) nanocomb structures have been prepared by a vapor-liquid-solid technique from a mixture of ZnO nanoparticles and graphene nanoplatelets. The ZnO seed nanoparticles were synthesized via a simple precipitation method. The structure of the ZnO nanocombs could easily be controlled by tuning the carrier-gas flow rate during growth. Higher flow rate resulted in the formation of uniformly-distributed single-sided comb structures with nanonail-shaped teeth, as a result of the self-catalysis effect of the catalytically active Zn-terminated polar (0001) surface. Lower gas flow rate was favorable for production of double-sided comb structures with the two sets of teeth at an angle of similar to 110 degrees to each other along the comb ribbon, which was attributed to the formation of a bicrystal nanocomb ribbon. The formation of such a double-sided structure with nanonail-shaped teeth has not previously been reported.

  14. Electroluminescence from ZnO/Si heterojunctions fabricated by PLD with bias voltage application

    SciTech Connect (OSTI)

    Seno, Yuuki; Konno, Daisuke; Komiyama, Takao; Chonan, Yasunori; Yamaguchi, Hiroyuki; Aoyama, Takashi

    2014-02-21

    Electroluminescence (EL) for ZnO films has been investigated by fabricating n-ZnO/p-Si heterojunctions and changing the VI/II (O/Zn) ratio of the films. In the photoluminescence (PL) spectra, both the near band edge (NBE) emission and the defect-related emission were observed, while in the EL spectra only defect-related emission was observed. The EL spectra were divided into three components: green (550 nm), yellow (618 nm) and red (700 nm) bands; and their intensities were compared. As the VI/II (O/Zn) ratio was increased, the red band emission intensity decreased and the green band emission intensity increased. This implies that the oxygen and the zinc vacancies are related to the red and the green band emissions, respectively. Electron transitions from the conduction band minimum (Ec) to the deep energy levels of these vacancies are suggested to cause the red and the green luminescences while the energy levels of the Zn interstitials are close to the Ec in the band gap and no NBE emission is observed.

  15. Visible light plasmonic heating of Au-ZnO for the catalytic reduction of CO2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Congjun; Ranasingha, Oshadha; Natesakhawat, Sittichai; Ohodnicki, Paul R.; Andio, Mark; Lewis, James P.; Matranga, Christopher

    2013-01-01

    Plasmonic excitation of Au nanoparticles attached to the surface of ZnO catalysts using low power 532 nm laser illumination leads to significant heating of the catalyst and the conversion of CO2 and H2 reactants to CH4 and CO products. Temperature-calibrated Raman spectra of ZnO phonons show that intensity-dependent plasmonic excitation can controllably heat Au–ZnO from 30 to ~600 °C and simultaneously tune the CH4 : CO product ratio. The laser induced heating and resulting CH4 : CO product distribution agrees well with predictions from thermodynamic models and temperature-programmed reaction experiments indicating that the reaction is a thermally driven process resultingmore » from the plasmonic heating of the Au-ZnO. The apparent quantum yield for CO2 conversion under continuous wave (cw) 532 nm laser illumination is 0.030%. The Au-ZnO catalysts are robust and remain active after repeated laser exposure and cycling. The light intensity required to initiate CO2 reduction is low ( ~2.5 x 105 W m-2) and achievable with solar concentrators. Our results illustrate the viability of plasmonic heating approaches for CO2 utilization and other practical thermal catalytic applications.« less

  16. Pd?Cd11? (0.21???0.51)a partly disordered ?-brass type phase and Pd?.???Cd?.??? -a ?-brass related incommensurate phase in the palladiumcadmium system

    SciTech Connect (OSTI)

    Jana, Partha Pratim; Lidin, Sven

    2013-05-01

    The Cd rich part of the CdPd phase diagram was reassessed by means of synthesis and single crystal and powder X-ray diffraction. The region contains two phases that have been reported to have substantial compositional widths, Cd??Pd? and Cd?Pd. The phase Cd??Pd? that has previously been reported to be a disordered ?-brass crystallizing is space group P4-bar 3m is here shown to crystallize in I4-bar 3m and the mechanism for compositional variation is explained. The phase Pd?Cd has previously been shown to constitute a phase field or a phase bundle of modulated structures and here we determine the structure of a compound Pd?.???Cd?.??? which crystallizes in the orthorhombic superspace group mm(?00)0s0 (F=[(, , 0, 0); (, 0, , 0 ); (0, , , 0 )] with the fundamental cell dimensions a=4.687(2) , b=10.000(1) , c=14.140(2) , q=0.6432(6)a?. - Graphical abstract: The crystal structures of the partly disordered ?-brass type Pd?Cd11? (0.21???0.51) and ?-brass related Pd?.???Cd?.??? in the palladiumcadmium binary system. Highlights: Partly disordered ?-brass type Pd?Cd11? (0.21???0.51) and ?-brass related Pd?.???Cd?.??? have been synthesized. The Pd?Cd11? structure have been described by cluster concept. Incommensurately modulated Pd?.???Cd?.??? have been described by (3+1) D space description. The structure of Pd?.???Cd?.??? has two different chains of atomic subunits, each with their own translational periodicities.

  17. High-throughput manufacturing of thin-film CdS/CdTe photovoltaic modules. Annual subcontract report, 16 November 1994--15 November 1995

    SciTech Connect (OSTI)

    Sandwisch, D.W. [Solar Cells, Inc., Toledo, OH (United States)

    1997-02-01

    The objectives of this subcontract are to advance Solar Cells, Inc.`s (SCI`s) photovoltaic manufacturing technologies, reduce module production costs, increase module performance, and provide the groundwork for SCI to expand its commercial production capacities. Activities during the second year of the program concentrated on process development, equipment design and testing, quality assurance, and ES and H programs. These efforts broadly addressed the issues of the manufacturing process for producing thin-film monolithic CdS/CdTe photovoltaic modules.

  18. Computational identification of single-layer CdO for electronic and optical applications

    SciTech Connect (OSTI)

    Zhuang, Houlong L.; Hennig, Richard G., E-mail: rhennig@cornell.edu [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States)

    2013-11-18

    The search for single-layer materials is an active research field. Using a first-principles design approach focusing on formation energy and bandgap, we search the family of II-VI oxides for metastable single-layer semiconductor materials. We discover a single-layer CdO phase that exhibits a small formation energy and a direct bandgap of 2.1?eV. The phonon spectrum confirms the dynamical stability of single-layer CdO. Calculations of the optical properties show a similar absorption to that of graphene. Estimates of the tunneling barrier of a graphene/CdO/graphene heterostructure reveal that CdO might be a potential dielectric for applications of graphene in electronic devices.

  19. Calculated transport properties of CdO: thermal conductivity and thermoelectric power factor

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lindsay, Lucas R.; Parker, David S.

    2015-10-01

    We present first principles calculations of the thermal and electronic transport properties of the oxide semiconductor CdO. In particular, we find from theory that the accepted thermal conductivity κ value of 0.7 Wm-1K-1 is approximately one order of magnitude too small; our calculations of κ of CdO are in good agreement with recent measurements. We also find that alloying of MgO with CdO is an effective means to reduce the lattice contribution to κ, despite MgO having a much larger thermal conductivity. We further consider the electronic structure of CdO in relation to thermoelectric performance, finding that large thermoelectric powermore » factors may occur if the material can be heavily doped p-type. This work develops insight into the nature of thermal and electronic transport in an important oxide semiconductor.« less

  20. Summary of EXAFS results on Cd-doped PuRhIn5 (Technical Report...

    Office of Scientific and Technical Information (OSTI)

    Citation Details In-Document Search Title: Summary of EXAFS results on Cd-doped PuRhIn5 Authors: Booth, C H ; Bauer, E D ; Tobin, J G Publication Date: 2014-06-12 OSTI Identifier: ...

  1. Influence of Ag doping concentration on structural and optical properties of CdS thin film

    SciTech Connect (OSTI)

    Kumar, Pragati; Saxena, Nupur; Gupta, Vinay; Agarwal, Avinash

    2015-05-15

    This work shows the influence of Ag concentration on structural properties of pulsed laser deposited nanocrystalline CdS thin film. X-ray photoelectron spectroscopy (XPS) studies confirm the dopant concentration in CdS films and atomic concentration of elements. XPS studies show that the samples are slightly sulfur deficient. GAXRD scan reveals the structural phase transformation from cubic to hexagonal phase of CdS without appearance of any phase of CdO, Ag{sub 2}O or Ag{sub 2}S suggesting the substitutional doping of Ag ions. Photoluminescence studies illustrate that emission intensity increases with increase in dopant concentration upto 5% and then decreases for higher dopant concentration.

  2. Calculated transport properties of CdO: thermal conductivity and thermoelectric power factor

    SciTech Connect (OSTI)

    Lindsay, Lucas R.; Parker, David S.

    2015-10-01

    We present first principles calculations of the thermal and electronic transport properties of the oxide semiconductor CdO. In particular, we find from theory that the accepted thermal conductivity κ value of 0.7 Wm-1K-1 is approximately one order of magnitude too small; our calculations of κ of CdO are in good agreement with recent measurements. We also find that alloying of MgO with CdO is an effective means to reduce the lattice contribution to κ, despite MgO having a much larger thermal conductivity. We further consider the electronic structure of CdO in relation to thermoelectric performance, finding that large thermoelectric power factors may occur if the material can be heavily doped p-type. This work develops insight into the nature of thermal and electronic transport in an important oxide semiconductor.

  3. Atomic-force microscopy and photoluminescence of nanostructured CdTe

    SciTech Connect (OSTI)

    Babentsov, V.; Sizov, F.; Franc, J.; Luchenko, A.; Svezhentsova, E. Tsybrii, Z.

    2013-09-15

    Low-dimensional CdTe nanorods with a diameter of 10-30 nm and a high aspect ratio that reaches 100 are studied. The nanorods are grown by the physical vapor transport method with the use of Bi precipitates on the substrates. In addition, thin films of closely packed CdTe nanorods with the transverse dimensions {approx}(100-200) nm are grown. Atomic-force microscopy shows that the cross sections of all of the nanorods were hexagonally shaped. By photoluminescence measurements, the inference about the wurtzite structure of CdTe is supported, and the structural quality, electron-phonon coupling, and defects are analyzed. On the basis of recent ab initio calculations, the nature of defects responsible for the formation of deep levels in the CdTe layers and bulk crystals are analyzed.

  4. NREL Collaboration Boosts Potential for CdTe Solar Cells - News Releases |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    NREL NREL Collaboration Boosts Potential for CdTe Solar Cells February 29, 2016 A critical milestone has been reached in cadmium telluride (CdTe) solar cell technology, helping pave the way for solar energy to directly compete with electricity generated by conventional energy sources. Scientists at the Energy Department's National Renewable Energy Laboratory (NREL) collaborated with researchers at Washington State University and the University of Tennessee to improve the maximum voltage

  5. Nanoscale mapping of plasmon and exciton in ZnO tetrapods coupled with Au nanoparticles

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bertoni, Giovanni; Fabbri, Filippo; Villani, Marco; Lazzarini, Laura; Turner, Stuart; Van Tendeloo, Gustaaf; Calestani, Davide; Gradečak, Silvija; Zappettini, Andrea; Salviati, Giancarlo

    2016-01-12

    Metallic nanoparticles can be used to enhance optical absorption or emission in semiconductors, thanks to a strong interaction of collective excitations of free charges (plasmons) with electromagnetic fields. Herein we present direct imaging at the nanoscale of plasmon-exciton coupling in Au/ZnO nanostructures by combining scanning transmission electron energy loss and cathodoluminescence spectroscopy and mapping. The Au nanoparticles (~30 nm in diameter) are grown in-situ on ZnO nanotetrapods by means of a photochemical process without the need of binding agents or capping molecules, resulting in clean interfaces. Interestingly, the Au plasmon resonance is localized at the Au/vacuum interface, rather than presentingmore » an isotropic distribution around the nanoparticle. Moreover, on the contrary, a localization of the ZnO signal has been observed inside the Au nanoparticle, as also confirmed by numerical simulations.« less

  6. ZnO/Ag composite nanorod arrays for surface-plasmon-enhanced emission study

    SciTech Connect (OSTI)

    Pal, Anil Kumar E-mail: d.bharathimohan@gmail.com; Mohan, D. Bharathi E-mail: d.bharathimohan@gmail.com

    2014-04-24

    The surface plasmon resonance enhanced emission through coupling of surface plasmons and exciton band energies is studied in hybrid ZnO/Ag nanostructure. The catalytic growth of ZnO nanorods is controlled in seed mediated growth by altering size distribution of Ag nanoislands. X-ray diffraction shows a predominant (002) crystal plane confirming the preferential growth of ZnO nanorods on as-deposited Ag. Increase of surface roughness in Ag film by post deposition annealing process enhances the light emission due to momentum matching between surface plasmons and excitons as well as a red shift of 32 meV occurs due to multi phonon and phonon-exciton interaction.

  7. Effect of Fe doping concentration on photocatalytic activity of ZnO nanosheets under natural sunlight

    SciTech Connect (OSTI)

    Khokhra, Richa; Kumar, Rajesh

    2015-05-15

    A facile room temperature, aqueous solution-based chemical method has been adopted for large-scale synthesis of Fe doped ZnO nanosheets. The XRD and SEM results reveal the as-synthesized products well crystalline and accumulated by large amount of interweave nanosheets, respectively. Energy dispersive spectroscopy data confirmed Fe doping of the ZnO nanosheets with a varying Fe concentration. The photoluminescence spectrum reveals a continuous suppression of defect related emissions intensity by increasing the concentration of the Fe ion. A photocatalytic activity using these samples under sunlight irradiation in the mineralization of methylene blue dye was investigated. The photocatalytic activity of Fe doped ZnO nanosheets depends upon the presence of surface oxygen vacancies.

  8. Band alignment and interfacial structure of ZnO/Si heterojunction with

    Office of Scientific and Technical Information (OSTI)

    Al{sub 2}O{sub 3} and HfO{sub 2} as interlayers (Journal Article) | SciTech Connect Band alignment and interfacial structure of ZnO/Si heterojunction with Al{sub 2}O{sub 3} and HfO{sub 2} as interlayers Citation Details In-Document Search Title: Band alignment and interfacial structure of ZnO/Si heterojunction with Al{sub 2}O{sub 3} and HfO{sub 2} as interlayers Energy band alignment of ZnO/Si heterojunction with thin interlayers Al{sub 2}O{sub 3} and HfO{sub 2} grown by atomic layer

  9. A Novel and Functional Single Layer Sheet of ZnSe

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhou, Jia; Sumpter, Bobby G; Kent, Paul R; Huang, Jingsong

    2015-01-01

    In this Communication, we report a novel singlelayer sheet of ZnSe, with a three-atomic thickness, which demonstrates a strong quantum confinement effect by exhibiting a large blue shift of 2.0 eV in its absorption edge relative to the zinc blende (ZB) bulk phase. Theoretical optical absorbance shows that the largest absorption of this ultrathin single-layer sheet of ZnSe occurs at a wavelength similar to its four-atom-thick doublelayer counterpart but with higher photoabsorption efficiency, suggesting a superior behavior on incident photon-to-current conversion efficiency for solar water splitting, among other potential applications. The results presented herein for ZnSe may be generalized tomore » other group II-VI analogues.« less

  10. Homojunction p-n photodiodes based on As-doped single ZnO nanowire

    SciTech Connect (OSTI)

    Cho, H. D.; Zakirov, A. S.; Yuldashev, Sh. U.; Kang, T. W.; Ahn, C. W.; Yeo, Y. K.

    2013-12-04

    Photovoltaic device was successfully grown solely based on the single ZnO p-n homojunction nanowire. The ZnO nanowire p-n diode consists of an as-grown n-type segment and an in-situ arsenic doped p-type segment. This p-n homojunction acts as a good photovoltaic cell, producing a photocurrent almost 45 times larger than the dark current under reverse-biased condition. Our results demonstrate that present ZnO p-n homojunction nanowire can be used as a self-powered ultraviolet photodetector as well as a photovoltaic cell, which can also be used as an ultralow electrical power source for nano-scale electronic, optoelectronic, and medical devices.

  11. Structural analysis of Cr aggregation in ferromagnetic semiconductor (Zn,Cr)Te

    SciTech Connect (OSTI)

    Kobayashi, H.; Yamawaki, K.; Nishio, Y.; Kanazawa, K.; Kuroda, S.; Mitome, M.; Bando, Y.

    2013-12-04

    The Cr aggregation in a ferromagnetic semiconductor (Zn,Cr)Te was studied by performing precise analyses using TEM and XRD of microscopic structure of the Cr-aggregated regions formed in iodine-doped Zn{sub 1?x}Cr{sub x}Te films with a relatively high Cr composition x ? 0.2. It was found that the Cr-aggregated regions are composed of Cr{sub 1??}Te nanocrystals of the hexagonal structure and these hexagonal precipitates are stacked preferentially on the (111)A plane of the zinc-blende (ZB) structure of the host ZnTe crystal with its c-axis nearly parallel to the (111){sub ZB} plane.

  12. Targeting CD9 produces stimulus-independent antiangiogenic effects predominantly in activated endothelial cells during angiogenesis: A novel antiangiogenic therapy

    SciTech Connect (OSTI)

    Kamisasanuki, Taro; Department of Ophthalmology, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima 890-8544 ; Tokushige, Saori; Terasaki, Hiroto; Department of Ophthalmology, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima 890-8544 ; Khai, Ngin Cin; Wang, Yuqing; Sakamoto, Taiji; Kosai, Ken-ichiro

    2011-09-16

    Highlights: {yields} CD9 plays stimulus-independent roles in angiogenesis in vitro and in vivo. {yields} Targeting CD9 expression is effective in an angiogenic disease model. {yields} Targeting CD9 expression predominantly affects activated endothelial cells. {yields} CD9 is involved in endothelial cell proliferation, but not survival. {yields} CD9 is part of angiogenic machinery in endothelial cells during angiogenesis. -- Abstract: The precise roles of tetraspanin CD9 are unclear. Here we show that CD9 plays a stimulus-independent role in angiogenesis and that inhibiting CD9 expression or function is a potential antiangiogenic therapy. Knocking down CD9 expression significantly inhibited in vitro endothelial cell migration and invasion induced by vascular endothelial growth factor (VEGF) or hepatocyte growth factor (HGF). Injecting CD9-specific small interfering RNA (siRNA-CD9) markedly inhibited HGF- or VEGF-induced subconjunctival angiogenesis in vivo. Both results revealed potent and stimulus-independent antiangiogenic effects of targeting CD9. Furthermore, intravitreous injections of siRNA-CD9 or anti-CD9 antibodies were therapeutically effective for laser-induced retinal and choroidal neovascularization in mice, a representative ocular angiogenic disease model. In terms of the mechanism, growth factor receptor and downstream signaling activation were not affected, whereas abnormal localization of integrins and membrane type-1 matrix metalloproteinase was observed during angiogenesis, by knocking down CD9 expression. Notably, knocking down CD9 expression did not induce death and mildly inhibited proliferation of quiescent endothelial cells under conditions without an angiogenic stimulus. Thus, CD9 does not directly affect growth factor-induced signal transduction, which is required in angiogenesis and normal vasculature, but is part of the angiogenesis machinery in endothelial cells during angiogenesis. In conclusion, targeting CD9 produced stimulus-independent antiangiogenic effects predominantly in activated endothelial cells during angiogenesis, and appears to be an effective and safe antiangiogenic approach. These results shed light on the biological roles of CD9 and may lead to novel antiangiogenic therapies.

  13. Study of difference in interfacial reaction at Fe{sub 3}O{sub 4}/ZnO and ZnO/Fe{sub 3}O{sub 4} heterostructure using synchrotron radiation

    SciTech Connect (OSTI)

    Wadikar, A. D. Master, Ridhi Choudhary, R. J. Phase, D. M.

    2014-04-24

    We have prepared Fe{sub 3}O{sub 4}/ZnO and ZnO/Fe{sub 3}O{sub 4} bilayer structure on p-Si substrate using pulsed laser deposition technique (PLD). X-ray diffraction study revealed (0001) oriented growth of ZnO and (111) oriented growth of Fe{sub 3}O{sub 4} in both the bilayer structure. We observed a change in the density of states near the Fermi level in valence band spectra in case of Fe{sub 3}O{sub 4}/ZnO bilayer when compared to that of ZnO/Fe{sub 3}O{sub 4}. Nonlinear current–voltage (I-V) characteristics were observed in both the samples confirmed that these bilayer structures can be used for spintronic application.

  14. Reduction of Fermi level pinning and recombination at polycrystalline CdTe surfaces by laser irradiation

    SciTech Connect (OSTI)

    Simonds, Brian J.; Kheraj, Vipul; Palekis, Vasilios; Ferekides, Christos; Scarpulla, Michael A.

    2015-06-14

    Laser processing of polycrystalline CdTe is a promising approach that could potentially increase module manufacturing throughput while reducing capital expenditure costs. For these benefits to be realized, the basic effects of laser irradiation on CdTe must be ascertained. In this study, we utilize surface photovoltage spectroscopy (SPS) to investigate the changes to the electronic properties of the surface of polycrystalline CdTe solar cell stacks induced by continuous-wave laser annealing. The experimental data explained within a model consisting of two space charge regions, one at the CdTe/air interface and one at the CdTe/CdS junction, are used to interpret our SPS results. The frequency dependence and phase spectra of the SPS signal are also discussed. To support the SPS findings, low-temperature spectrally-resolved photoluminescence and time-resolved photoluminescence were also measured. The data show that a modest laser treatment of 250 W/cm{sup 2} with a dwell time of 20 s is sufficient to reduce the effects of Fermi level pinning at the surface due to surface defects.

  15. Probing the size and environment induced phase transformation in CdSe quantum dots

    SciTech Connect (OSTI)

    Karakoti, Ajay S.; Sanghavi, Shail P.; Nachimuthu, Ponnusamy; Yang, Ping; Thevuthasan, Suntharampillai

    2011-11-17

    The structural and electronic properties of CdSe quantum dots in toluene and drop-casted on Si wafer were investigated by in-situ micro X-ray diffraction, X-ray photoelectron spectroscopy and UV-Vis absorption and emission spectroscopy. The in-situ micro diffraction data show that the CdSe quantum dots capped with TOPO or hexadecylamine (HDA) in toluene exhibit predominantly wurtzite crystal structure, which undergoes a phase transformation to zinc blende crystal structure following drop casting on Si and this phase transition increases with decreasing the size of the CdSe quantum dots. Decreasing the size of quantum dots also increases the Se vacancies that facilitate the phase transformation. The X-ray photoelectron spectra show a systematic increase in the core level binding energies of Cd 3d and Se 3d, the band gap and the Cd/Se ratio as the size of the quantum dots decreases from 6.6nm to 2.1nm. This is attributed to the quantum confinement of CdSe crystallites by the capping ligands in toluene which increases with decreasing the size of the quantum dots. However, drop-casting quantum dots on Si alter the density and arrangement of capping ligands and solvent molecules on the quantum dots which causes significant phase transformation.

  16. Synthesis of uniform CdS nanowires in high yield and its single nanowire electrical property

    SciTech Connect (OSTI)

    Yan Shancheng; Sun Litao; Qu Peng; Huang Ninping; Song Yinchen; Xiao Zhongdang

    2009-10-15

    Large-scale high quality CdS nanowires with uniform diameter were synthesized by using a rapid and simple solvothermal route. Field emission scan electron microscopy (FESEM) and transmission electron microscopy (TEM) images show that the CdS nanowires have diameter of about 26 nm and length up to several micrometres. High resolution TEM (HRTEM) study indicates the single-crystalline nature of CdS nanowires with an oriented growth along the c-axis direction. The optical properties of the products were characterized by UV-vis absorption spectra, photoluminescence spectra and Raman spectra. The resistivity, electron concentration and electron mobility of single NW are calculated by fitting the symmetric I-V curves measured on single NW by the metal-semiconductor-metal model based on thermionic field emission theory. - Graphical abstract: Large-scale high quality CdS nanowires (NWs) with uniform diameter were synthesized by using a rapid and simple solvothermal route. The reaction time is reduced to 2 h, comparing to other synthesis which needed long reaction time up to 12 h. In addition, the as-prepared CdS nanowires have more uniform diameter and high yield. More importantly, the I-V curve of present single CdS nanowire has a good symmetric characteristic as expected by the theory.

  17. Enhanced thermoelectric performance in Cd doped CuInTe{sub 2} compounds

    SciTech Connect (OSTI)

    Cheng, N.; Liu, R.; Bai, S.; Shi, X. Chen, L.

    2014-04-28

    CuIn{sub 1?x}Cd{sub x}Te{sub 2} materials (x?=?0, 0.02, 0.05, and 0.1) are prepared using melting-annealing method and the highly densified bulk samples are obtained through Spark Plasma Sintering. The X-ray diffraction data confirm that nearly pure chalcopyrite structures are obtained in all the samples. Due to the substitution of Cd at In sites, the carrier concentration is greatly increased, leading to much enhanced electrical conductivity and power factor. The single parabolic band model is used to describe the electrical transport properties of CuInTe{sub 2} and the low temperature Hall mobility is also modeled. By combing theoretical model and experiment data, the optimum carrier concentration in CuInTe{sub 2} is proposed to explain the greatly enhanced power factors in the Cd doped CuInTe{sub 2}. In addition, the thermal conductivity is reduced by extra phonon scattering due to the atomic mass and radius fluctuations between Cd and In atoms. The maximum zTs are observed in CuIn{sub 0.98}Cd{sub 0.02}Te{sub 2} and CuIn{sub 0.9}Cd{sub 0.1}Te{sub 2} samples, which are improved by over 100% at room temperature and around 20% at 600?K.

  18. Scalable economic extracellular synthesis of CdS nanostructured particles by a non-pathogenic thermophile

    SciTech Connect (OSTI)

    Moon, Ji Won; Ivanov, Ilia N; Duty, Chad E; Love, Lonnie J; Rondinone, Adam Justin; Wang, Wei; Li, Dr. Yi-Liang; Madden, Andrew; Mosher, Jennifer J; Hu, Michael Z.; Suresh, Anil K; Rawn, Claudia J; Jung, Hyunsung; Lauf, Robert J; Phelps, Tommy Joe

    2013-01-01

    We report microbially facilitated synthesis of cadmium sulfide (CdS) nanostructured particles (NP) using anaerobic, metal-reducing Thermoanaerobacter sp. The extracellular CdS crystallites were <10 nm in size with yields of ~3 g/L of growth medium/month with demonstrated reproducibility and scalability up to 24 L. During synthesis, Thermoanaerobacter cultures reduced thiosulfate and sulfite salts to H2S, which reacted with Cd2+ cations to produce thermodynamically favored NP in a single step at 65oC with catalytic nucleation on the cell surfaces. Photoluminescence (PL) analysis of dry CdS NP revealed an exciton-dominated PL peak at 440 nm, having a narrow full width at half maximum of 10 nm. A PL spectrum of CdS NP produced by dissimilatory sulfur reducing bacteria was dominated by features associated with radiative exciton relaxation at the surface. High reproducibility of CdS NP PL features important for scale-up conditions was confirmed from test tubes to 24L batches at a small fraction of the manufacturing cost associated with conventional inorganic NP production processes.

  19. ZnO Nanorod Thermoplastic Polyurethane Nanocomposites: Morphology and Shape Memory Performance

    SciTech Connect (OSTI)

    Koerner, H.; Kelley, J; George, J; Drummy, L; Mirau, P; Bell, N; Hsu, J; Vaia, R

    2009-01-01

    The impact of dispersed alkylthiol-modified ZnO nanorods, as a function of rod aspect ratio and concentration, on the shape memory character of a thermoplastic polyurethane with low hard-segment density (LHS-TPU) is examined relative to the enhanced performance occurring for carbon nanofiber (CNF) dispersion. Solution blending resulted in uniform dispersion within the LHS-TPU of the ZnO nanorods at low volume (weight) fractions (<2.9% v/v (17.75% w/w)). Tensile modulus enhancements were modest though, comparable to values observed for spherical nanofillers. Shape memory characteristics, which in this LHS-TPU result when strain-induced crystallites retard the entropic recovery of the deformed chains, were unchanged for these low volume fraction ZnO nanocomposites. Higher ZnO loadings (12% v/v (50% w/w)) exhibited clustering of ZnO nanorods into a mesh-like structure. Here, tensile modulus and shape recovery characteristics were improved, although not as great as seen for comparable CNF addition. Wide angle X-ray diffraction and NMR revealed that the addition of ZnO nanorods did not impact the inherent strain induced crystallization of the LHS-TPU, which is in contrast to the impact of CNFs and emphasizes the impact of interactions at the polymer-nanoparticle interface. Overall, these findings reinforce the hypothesis that the shape memory properties of polymer nanocomposites are governed by the extent to which nanoparticle addition, via nanoparticle aspect ratio, hierarchical morphology, and interfacial interactions, impacts the molecular mechanism responsible for trapping elastic strain.

  20. Characteristics of ZnO nanostructures produced with [DMIm]BF{sub 4} using ultrasonic radiation

    SciTech Connect (OSTI)

    Rahman, I. B. Abdul; Ayob, M. T. M.; Ishak, I. S.; Mohd Lawi, R. L.; Isahak, W. N. R. W.; Hamid, M. H. N. Abd; Othman, N. K.; Radiman, S.

    2012-11-27

    Great interests in metallic oxides have emerged because of the promising properties of these materials for various applications such as solar cells and sensors. ZnO nanostructures with different morphologies were successfully synthesized from Zn(CH{sub 3}COO){sub 2} Bullet 2H{sub 2}O, NaOH and room temperature ionic liquid (RTIL) 1-decyl-3-methylimidazolium tetrafluoroborate, [DMIm][BF{sub 4}] with ultrasound irradiation. Parameters such as the effect of sonication time (30, 60 and 90 minutes) and Zn(Ac){sub 2} precursor to [DMIm][BF{sub 4}] ratios of 3:5, 5:5 and 5:3 were investigated. X-ray diffraction patterns revealed that the ZnO nanocrystals were hexagonal zincite crystalline in structure. The band gap energies (E{sub g}) were estimated to be 3.35-3.55 eV from the UV-Visible spectrum. The solution with the highest ratio of Zn was analysed with photoluminescence spectroscopy, which exhibited peaks at 362, 403, 468 and 539 nm, at room temperature. The micrographs of field emission scanning electron microscopy and transmission electron microscopy showed that the synthesis products were spherical (30-60 nm), spindle ({approx}10 Multiplication-Sign 70 nm for width Multiplication-Sign length) and whisker-like (100-200 nm), with their dimensions decreasing systematically with increased sonication time. Chemical compositions were approximated at 1:1 for Zn and O, estimated by electron dispersive x-ray spectrum.

  1. Surface Modification of ZnO Using Triethoxysilane-Based Molecules

    SciTech Connect (OSTI)

    Allen, C. G.; Baker, D. J.; Albin, J. M.; Oertli, H. E.; Gillaspie, D. T.; Olson, D. C.; Furtak, T. E.; Collins, R. T.

    2008-12-01

    Zinc oxide (ZnO) is an important material for hybrid inorganic-organic devices in which the characteristics of the interface can dominate both the structural and electronic properties of the system. These characteristics can be modified through chemical functionalization of the ZnO surface. One of the possible strategies involves covalent bonding of the modifier using silane chemistry. Whereas a significant body of work has been published regarding silane attachments to glass and SiO{sub 2}, there is less information about the efficacy of this method for controlling the surface of metal oxides. Here we report our investigation of molecular layers attached to polycrystalline ZnO through silane bonding, controlled by an amine catalyst. The catalyst enables us to use triethoxysilane precursors and thereby avoid undesirable multilayer formation. The polycrystalline surface is a practical material, grown by sol-gel processing, that is under active exploration for device applications. Our study included terminations with alkyl and phenyl groups. We used water contact angles, infrared spectroscopy, and X-ray photoemission spectroscopy to evaluate the modified surfaces. Alkyltriethoxysilane functionalization of ZnO produced molecular layers with submonolayer coverage and evidence of disorder. Nevertheless, a very stable hydrophobic surface with contact angles approaching 106{sup o} resulted. Phenyltriethoxysilane was found to deposit in a similar manner. The resulting surface, however, exhibited significantly different wetting as a result of the nature of the end group. Molecular layers of this type, with a variety of surface terminations that use the same molecular attachment scheme, should enable interface engineering that optimizes the chemical selectivity of ZnO biosensors or the charge-transfer properties of ZnO-polymer interfaces found in oxide-organic electronics.

  2. Study of Even-Even/Odd-Even/Odd-Odd Nuclei in Zn-Ga-Ge Region in the Proton-Neutron IBM/IBFM/IBFFM

    SciTech Connect (OSTI)

    Yoshida, N.; Brant, S.; Zuffi, L.

    2009-08-26

    We study the even-even, odd-even and odd-odd nuclei in the region including Zn-Ga-Ge in the proton-neutron IBM and the models derived from it: IBM2, IBFM2, IBFFM2. We describe {sup 67}Ga, {sup 65}Zn, and {sup 68}Ga by coupling odd particles to a boson core {sup 66}Zn. We also calculate the beta{sup +}-decay rates among {sup 68}Ge, {sup 68}Ga and {sup 68}Zn.

  3. Passivation of an isoelectronic impurity by atomic hydrogen: The case of ZnTe:O

    SciTech Connect (OSTI)

    Felici, Marco; Polimeni, Antonio; Capizzi, Mario; Nabetani, Y.; Okuno, T.; Aoki, K.; Kato, T.; Matsumoto, T.; Hirai, T.

    2006-03-06

    We investigated the optical properties of ZnTe:O/GaAs before and after atomic hydrogen irradiation. Oxygen incorporation gives rise to energy levels associated with single O atoms, O-O pairs, and O clusters, and to a blueshift of the energy gap of the material with respect to that of pure ZnTe/GaAs. All of these effects disappear progressively after irradiation with H, which also leads to an increase in the tensile strain of the epilayer. These observations provide experimental evidence of H-induced passivation of an isoelectronic impurity in II-VI alloys.

  4. Evolution of quasiparticle states with and without a Zn impurity in doped

    Office of Scientific and Technical Information (OSTI)

    122 iron pnictides (Journal Article) | SciTech Connect Evolution of quasiparticle states with and without a Zn impurity in doped 122 iron pnictides Citation Details In-Document Search Title: Evolution of quasiparticle states with and without a Zn impurity in doped 122 iron pnictides Authors: Pan, Lihua ; Li, Jian ; Tai, Yuan-Yen ; Graf, Matthias J. ; Zhu, Jian-Xin ; Ting, C. S. Publication Date: 2014-10-01 OSTI Identifier: 1180664 Grant/Contract Number: AC52-06NA25396 Type: Publisher's

  5. Hierarchical ZnO Structures Templated with Amino Acid Based Surfactants

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Hierarchical ZnO Structures Templated with Amino Acid Based Surfactants Citation Details In-Document Search Title: Hierarchical ZnO Structures Templated with Amino Acid Based Surfactants Authors: Kim, S H ; Satcher, J H ; Han, T Y Publication Date: 2011-05-27 OSTI Identifier: 1184130 Report Number(s): LLNL-JRNL-485258 DOE Contract Number: DE-AC52-07NA27344 Resource Type: Journal Article Resource Relation: Journal Name: Microporous and Mesoporous Materials,

  6. Native point defects and doping in ZnGeN 2 (Journal Article) | DOE PAGES

    Office of Scientific and Technical Information (OSTI)

    Native point defects and doping in ZnGeN 2 This content will become publicly available on April 11, 2017 « Prev Next » Title: Native point defects and doping in ZnGeN 2 Authors: Skachkov, Dmitry ; Punya Jaroenjittichai, Atchara ; Huang, Ling-yi ; Lambrecht, Walter R. L. Publication Date: 2016-04-11 OSTI Identifier: 1246761 Type: Publisher's Accepted Manuscript Journal Name: Physical Review B Additional Journal Information: Journal Volume: 93; Journal Issue: 15; Journal ID: ISSN 2469-9950

  7. Preparation and characterization of nanodiamond cores coated with a thin Ni-Zn-P alloy film

    SciTech Connect (OSTI)

    Wang Rui; Ye Weichun; Ma Chuanli; Wang Chunming

    2008-02-15

    Nanodiamond cores coated with a thin Ni-Zn-P alloy film were prepared by an electroless deposition method under the conditions of tin chloride sensitization and palladium chloride activation. The prepared materials were analyzed by Fourier transform infrared (FTIR) spectrometry and X-ray diffraction (XRD). The nanostructure of the materials was then characterized by transmission electron microscopy (TEM). The alloy film composition was characterized by Energy Dispersive X-ray (EDX) analysis. The results indicated the approximate composition 49.84%Ni-37.29%Zn-12.88%P was obtained.

  8. Diameter Control and Photoluminescence of ZnO Nanorods from Trialkylamines

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Andelman, Tamar; Gong, Yinyan; Neumark, Gertrude; O'Brien, Stephen

    2007-01-01

    A novel solution method to control the diameter of ZnO nanorods is reported. Small diameter (2-3 nm) nanorods were synthesized from trihexylamine, and large diameter (50–80 nm) nanorods were synthesized by increasing the alkyl chain length to tridodecylamine. The defect (green) emission of the photoluminescence (PL) spectra of the nanorods varies with diameter, and can thus be controlled by the diameter control. The small ZnO nanorods have strong green emission, while the large diameter nanorods exhibit a remarkably suppressed green band. We show that this observation supports surface oxygen vacancies as the defect that gives rise to the green emission.

  9. A Reversible Structural Phase Transition in ZnV2O6 at High Pressures

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect A Reversible Structural Phase Transition in ZnV2O6 at High Pressures Citation Details In-Document Search Title: A Reversible Structural Phase Transition in ZnV2O6 at High Pressures Authors: Tang, R. ; Li, Y. ; Han, D. ; Li, H. ; Zhao, Y. ; Gao, C. ; Zhu, P. ; Wang, X. Publication Date: 2014-05-22 OSTI Identifier: 1162417 Report Number(s): BNL--106361-2014-JA Journal ID: ISSN 1932--7447 DOE Contract Number: DE-AC02-98CH10886 Resource Type: Journal Article

  10. Evolution of crystal structure during the initial stages of ZnO atomic layer deposition

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Boichot, R.; Tian, L.; Richard, M. -I.; Crisci, A.; Chaker, A.; Cantelli, V.; Coindeau, S.; Lay, S.; Ouled, T.; Guichet, C.; et al

    2016-01-05

    In this study, a complementary suite of in situ synchrotron X-ray techniques is used to investigate both structural and chemical evolution during ZnO growth by atomic layer deposition. Focusing on the first 10 cycles of growth, we observe that the structure formed during the coalescence stage largely determines the overall microstructure of the film. Furthermore, by comparing ZnO growth on silicon with a native oxide with that on Al2O3(001), we find that even with lattice-mismatched substrates and low deposition temperatures, the crystalline texture of the films depend strongly on the nature of the interfacial bonds.

  11. The dependence of ZnO photoluminescence efficiency on excitation conditions and defect densities

    SciTech Connect (OSTI)

    Simmons, Jay G.; Liu, Jie; Foreman, John V.; Everitt, Henry O.

    2013-11-11

    The quantum efficiencies of both the band edge and deep-level defect emission from annealed ZnO powders were measured as a function of excitation fluence and wavelength from a tunable sub-picosecond source. A simple model of excitonic decay reproduces the observed excitation dependence of rate constants and associated trap densities for all radiative and nonradiative processes. The analysis explores how phosphor performance deteriorates as excitation fluence and energy increase, provides an all-optical approach for estimating the number density of defects responsible for deep-level emission, and yields new insights for designing efficient ZnO-based phosphors.

  12. New tetragonal derivatives of cubic NaZn{sub 13}-type structure: RNi{sub

    Office of Scientific and Technical Information (OSTI)

    6}Si{sub 6} compounds, crystal structure and magnetic ordering (R=Y, La, Ce, Sm, Gd-Yb) (Journal Article) | SciTech Connect New tetragonal derivatives of cubic NaZn{sub 13}-type structure: RNi{sub 6}Si{sub 6} compounds, crystal structure and magnetic ordering (R=Y, La, Ce, Sm, Gd-Yb) Citation Details In-Document Search Title: New tetragonal derivatives of cubic NaZn{sub 13}-type structure: RNi{sub 6}Si{sub 6} compounds, crystal structure and magnetic ordering (R=Y, La, Ce, Sm, Gd-Yb) Novel

  13. Discovery of a ternary pseudobrookite phase in the earth-abundant TiZnO

    Office of Scientific and Technical Information (OSTI)

    system (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Discovery of a ternary pseudobrookite phase in the earth-abundant TiZnO system Citation Details In-Document Search Title: Discovery of a ternary pseudobrookite phase in the earth-abundant TiZnO system Authors: Perry, Nicola H. ; Stevanovic, Vladan ; Lime, Linda Y. ; Mason, Thomas O. [1] ; CSM) [2] ; NWU) [2] ; MIT) [2] + Show Author Affiliations Stanford ( Publication Date: 2016-03-18 OSTI Identifier:

  14. Native point defects and doping in ZnGeN 2 (Journal Article) | SciTech

    Office of Scientific and Technical Information (OSTI)

    Connect SciTech Connect Search Results Journal Article: Native point defects and doping in ZnGeN 2 Citation Details In-Document Search This content will become publicly available on April 11, 2017 Title: Native point defects and doping in ZnGeN 2 Authors: Skachkov, Dmitry ; Punya Jaroenjittichai, Atchara ; Huang, Ling-yi ; Lambrecht, Walter R. L. Publication Date: 2016-04-11 OSTI Identifier: 1246761 Type: Publisher's Accepted Manuscript Journal Name: Physical Review B Additional Journal

  15. Dielectronic recombination of Zn-like W 44 + from Cu-like W 45 + (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Dielectronic recombination of Zn-like W 44 + from Cu-like W 45 + Citation Details In-Document Search This content will become publicly available on June 23, 2016 Title: Dielectronic recombination of Zn-like W 44 + from Cu-like W 45 + Authors: Safronova, U. I. ; Safronova, A. S. ; Beiersdorfer, P. Publication Date: 2015-06-24 OSTI Identifier: 1188517 Grant/Contract Number: AC52-07NA27344; NA0001984 Type: Publisher's Accepted Manuscript Journal Name: Physical Review

  16. CASL - Mixing and non-stoichiometry in Fe-Ni-Cr-Zn-O spinel compounds:

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Density functional theory calculations Mixing and non-stoichiometry in Fe-Ni-Cr-Zn-O spinel compounds: Density functional theory calculations Mixing and non-stoichiometry in Fe-Ni-Cr-Zn-O spinel compounds: Density functional theory calculations D.A. Andersson and C.R. Stanek Materials Science and Technology Division Los Alamos National Laboratory Density functional theory (DFT) calculations have been employed to better understand the thermodynamic properties of AB2O4 (where A=Fe2+, Ni2+ or

  17. Interaction of light with the ZnO surface: Photon induced oxygen breathing, oxygen vacancies, persistent photoconductivity, and persistent photovoltage

    SciTech Connect (OSTI)

    Gurwitz, Ron; Cohen, Rotem; Shalish, Ilan

    2014-01-21

    ZnO surfaces adsorb oxygen in the dark and emit CO{sub 2} when exposed to white light, reminiscent of the lungs of living creatures. We find that this exchange of oxygen with the ambient affects the integrity of the ZnO surface. Thus, it forms a basis for several interesting surface phenomena in ZnO, such as photoconductivity, photovoltage, and gas sensing, and has a role in ZnO electrical conduction. Using x-ray photoelectron spectroscopy on ZnO nanowires, we observed a decomposition of ZnO under white light and formation of oxygen-depleted surface, which explains photoconductivity by the electron donation of oxygen vacancies. Our findings suggest that the observed decomposition of the ZnO lattice may only take place due to photon-induced reduction of ZnO by carbon containing molecules (or carbo-photonic reduction), possibly from the ambient gas, accounting in a consistent way for both the reduced demands on the energy required for decomposition and for the observed emission of lattice oxygen in the form of CO{sub 2}. The formation of oxygen-vacancy rich surface is suggested to induce surface delta doping, causing accumulation of electrons at the surface, which accounts for both the increase in conductivity and the flattening of the energy bands. Using surface photovoltage spectroscopy in ultra high vacuum, we monitored changes in the deep level spectrum. We observe a wide optical transition from a deep acceptor to the conduction band, which energy position coincides with the position of the so called green luminescence in ZnO. This green transition disappears with the formation of surface oxygen vacancies. Since the oxygen vacancies are donors, while the green transition involves surface acceptors, the results suggest that the initial emission of oxygen originates at the defect sites of the latter, thereby eliminating each other. This suggests that the green transition originates at surface Zn vacancy acceptors. Removing an oxygen atom from a Zn vacancy completes the vacancy to become a full ZnO molecule vacancy, which does not produce deep levels. Our results explain why ZnO finds use as an electrical detector for oxygen and for carbon containing gas molecules. They may also shed new light on photocatalytic uses of ZnO. It is suggested that similar surface phenomena may affect other semiconducting oxides.

  18. Wide-bandgap high-mobility ZnO thin-film transistors produced at room temperature

    SciTech Connect (OSTI)

    Fortunato, Elvira M.C.; Barquinha, Pedro M.C.; Pimentel, Ana C.M.B.G.; Goncalves, Alexandra M.F.; Marques, Antonio J.S.; Martins, Rodrigo F.P.; Pereira, Luis M.N.

    2004-09-27

    We report high-performance ZnO thin-film transistor (ZnO-TFT) fabricated by rf magnetron sputtering at room temperature with a bottom gate configuration. The ZnO-TFT operates in the enhancement mode with a threshold voltage of 19 V, a saturation mobility of 27 cm{sup 2}/V s, a gate voltage swing of 1.39 V/decade and an on/off ratio of 3x10{sup 5}. The ZnO-TFT presents an average optical transmission (including the glass substrate) of 80% in the visible part of the spectrum. The combination of transparency, high mobility, and room-temperature processing makes the ZnO-TFT a very promising low-cost optoelectronic device for the next generation of invisible and flexible electronics.

  19. Rotational and angular distributions of NO products from NO-Rg(Rg = He, Ne, Ar) complex photodissociation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Heather L. Holmes-Ross; Hall, Gregory E.; Valenti, Rebecca J.; Yu, Hua -Gen; Lawrance, Warren D.

    2016-01-29

    In this study, we present the results of an investigation into the rotational and angular distributions of the NO A~ state fragment following photodissociation of the NO-He, NO-Ne and NO-Ar van der Waals complexed excited via the A~ ← X~ transition. For each complex the dissociation is probed for several values of Ea, the available energy above the dissociation threshold.

  20. Enhanced performance of branched TiO{sub 2} nanorod based Mn-doped CdS and Mn-doped CdSe quantum dot-sensitized solar cell

    SciTech Connect (OSTI)

    Kim, Soo-Kyoung; Gopi, Chandu V. V. M.; Lee, Jae-Cheol; Kim, Hee-Je

    2015-04-28

    TiO{sub 2} branched nanostructures could be efficient as photoanodes for quantum dot-sensitized solar cells (QDSCs) due to their large surface area for QD deposition. In this study, Mn-doped CdS/Mn-doped CdSe deposited branched TiO{sub 2} nanorods were fabricated to enhance the photovoltaic performance of QDSCs. Mn doping in CdS and CdSe retards the recombination losses of electrons, while branched TiO{sub 2} nanorods facilitate effective electron transport and compensate for the low surface area of the nanorod structure. As a result, the charge-transfer resistance (R{sub CT}), electron lifetime (?{sub e}), and the amount of QD deposition were significantly improved with branched TiO{sub 2} nanorod based Mn-doped CdS/Mn-doped CdSe quantum dot-sensitized solar cell.

  1. Effect of swift heavy ion irradiation on bare and coated ZnS quantum dots

    SciTech Connect (OSTI)

    Chowdhury, S. Hussain, A.M.P.; Ahmed, G.A.; Singh, F.; Avasthi, D.K.; Choudhury, A.

    2008-12-01

    The present study compares structural and optical modifications of bare and silica (SiO{sub 2}) coated ZnS quantum dots under swift heavy ion (SHI) irradiation. Bare and silica coated ZnS quantum dots were prepared following an inexpensive chemical route using polyvinyl alcohol (PVA) as the dielectric host matrix. X-ray diffraction (XRD) and transmission electron microscopy (TEM) study of the samples show the formation of almost spherical ZnS quantum dots. The UV-Vis absorption spectra reveal blue shift relative to bulk material in absorption energy while photoluminescence (PL) spectra suggests that surface state and near band edge emissions are dominating in case of bare and coated samples, respectively. Swift heavy ion irradiation of the samples was carried out with 160 MeV Ni{sup 12+} ion beam with fluences 10{sup 12} to 10{sup 13} ions/cm{sup 2}. Size enhancement of bare quantum dots after irradiation has been indicated in XRD and TEM analysis of the samples which has also been supported by optical absorption spectra. However similar investigations on irradiated coated quantum dots revealed little change in quantum dot size and emission. The present study thus shows that the coated ZnS quantum dots are stable upon SHI irradiation compared to the bare one.

  2. Fabrication of stable, wide-bandgap thin films of Mg, Zn and O

    DOE Patents [OSTI]

    Katiyar, Ram S.; Bhattacharya, Pijush; Das, Rasmi R.

    2006-07-25

    A stable, wide-bandgap (approximately 6 eV) ZnO/MgO multilayer thin film is fabricated using pulsed-laser deposition on c-plane Al2O3 substrates. Layers of ZnO alternate with layers of MgO. The thickness of MgO is a constant of approximately 1 nm; the thicknesses of ZnO layers vary from approximately 0.75 to 2.5 nm. Abrupt structural transitions from hexagonal to cubic phase follow a decrease in the thickness of ZnO sublayers within this range. The band gap of the thin films is also influenced by the crystalline structure of multilayer stacks. Thin films with hexagonal and cubic structure have band-gap values of 3.5 and 6 eV, respectively. In the hexagonal phase, Mg content of the films is approximately 40%; in the cubic phase Mg content is approximately 60%. The thin films are stable and their structural and optical properties are unaffected by annealing at 750.degree. C.

  3. ZnO-PVA nanocomposite films for low threshold optical limiting applications

    SciTech Connect (OSTI)

    Viswanath, Varsha; Beenakumari, C.; Muneera, C. I. [Department of Physics, University of Kerala, Kariavattom, Trivandrum-695581, Kerala (India)

    2014-10-15

    Zinc oxide-PVA nanocomposite films were fabricated adopting a simple method based on solution-casting, incorporating small weight percentages (<1.2 wt%) of ZnO in PVA (?0.62510{sup ?3}M to 710{sup ?3}M), and their structure, morphology, linear and low threshold nonlinear optical properties were investigated. The films were characterized as nanostructured ZnO encapsulated between the molecules/chains of the semicrystalline host polymer PVA. The samples exhibited low threshold nonlinear absorption and negative nonlinear refraction, as studied using the Z-scan technique. A switchover from SA to RSA was observed as the concentration of ZnO was increased. The optical limiting of 632.8 nm CW laser light displayed by these nanocomposite films is also demonstrated. The estimated values of the effective coefficients of nonlinear absorption, nonlinear refraction and third-order nonlinear susceptibility, |?{sup (3)}|, compared to those reported for continuous wave laser light excitation, measure up to the highest among them. The results show that the ZnO-PVA nanocomposite films have great potential applications in future optical and photonic devices.

  4. XRD, Photoluminescence and Optical Absorption Investigations of Cobalt-doped ZnO

    SciTech Connect (OSTI)

    Sujinnapram, Supphadate; Onreabroy, Wandee; Nantawisarakul, Tuangrak

    2009-07-07

    Zn{sub 1-x}Co{sub x}O(with x = 0, 0.01, 0.10 and 0.20) were synthesized by solid-state reaction method sintered at 600 deg. C for 12 hours. The samples were studied by X-ray diffraction (XRD), optical absorption (UV-Vis) and Photoluminescence (PL). Structural analysis by Rietveld method using XRD showed that the peaks of secondary phase Co{sub 3}O{sub 4} with a cubic structure were visible in the high-doped sample (x = 0.1, 0.2), besides the main peaks of wurtzite-like structure the same as that of ZnO. Shift of the XRD peaks proved the incorporation of Co{sup 2+} into the ZnO lattice. The band gap energy decreased from 3.18 to 3.14 eV with the increasing of cobalt concentration. PL spectra at room temperature showed the blue emission with the peak around 412 nm. In addition, the intensity of the blue emission decreased upon increasing the Co concentration, which indicated their high structural, defects and optical quality in the ZnO.

  5. Structurally ordered Pt–Zn/C series nanoparticles as efficient anode catalysts for formic acid electrooxidation

    SciTech Connect (OSTI)

    Zhu, Jing; Zheng, Xin; Wang, Jie; Wu, Zexing; Han, Lili; Lin, Ruoqian; Xin, Huolin L.; Wang, Deli

    2015-09-15

    Controlling the size, composition, and structure of bimetallic nanoparticles is of particular interest in the field of electrocatalysts for fuel cells. In the present work, structurally ordered nanoparticles with intermetallic phases of Pt3Zn and PtZn have been successfully synthesized via an impregnation reduction method, followed by post heat-treatment. The Pt3Zn and PtZn ordered intermetallic nanoparticles are well dispersed on a carbon support with ultrasmall mean particle sizes of ~5 nm and ~3 nm in diameter, respectively, which are credited to the evaporation of the zinc element at high temperature. These catalysts are less susceptible to CO poisoning relative to Pt/C and exhibited enhanced catalytic activity and stability toward formic acid electrooxidation. The mass activities of the as-prepared catalysts were approximately 2 to 3 times that of commercial Pt at 0.5 V (vs. RHE). As a result, this facile synthetic strategy is scalable for mass production of catalytic materials.

  6. Structurally ordered Pt–Zn/C series nanoparticles as efficient anode catalysts for formic acid electrooxidation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhu, Jing; Zheng, Xin; Wang, Jie; Wu, Zexing; Han, Lili; Lin, Ruoqian; Xin, Huolin L.; Wang, Deli

    2015-09-15

    Controlling the size, composition, and structure of bimetallic nanoparticles is of particular interest in the field of electrocatalysts for fuel cells. In the present work, structurally ordered nanoparticles with intermetallic phases of Pt3Zn and PtZn have been successfully synthesized via an impregnation reduction method, followed by post heat-treatment. The Pt3Zn and PtZn ordered intermetallic nanoparticles are well dispersed on a carbon support with ultrasmall mean particle sizes of ~5 nm and ~3 nm in diameter, respectively, which are credited to the evaporation of the zinc element at high temperature. These catalysts are less susceptible to CO poisoning relative to Pt/Cmore » and exhibited enhanced catalytic activity and stability toward formic acid electrooxidation. The mass activities of the as-prepared catalysts were approximately 2 to 3 times that of commercial Pt at 0.5 V (vs. RHE). As a result, this facile synthetic strategy is scalable for mass production of catalytic materials.« less

  7. Hydrothermal Synthesis and Structural Characterization of Novel Zn-Triazole-Benzenedicarboxylate Frameworks

    SciTech Connect (OSTI)

    Park, Hyunsoo; Moureau, David M.; Parise, John B.

    2008-10-03

    Three new metal-organic coordination polymers were synthesized hydrothermally using Zn2+ ion, 1,2,4-triazole, and 1,4-benzenedicarboxylic acid (BDC): Zn5(H2O)2(C2H2N3)4(C8H4O4)3 {center_dot} 3.9H2O (1), Zn2(C2H2N3)2(C2H3N3)(C8H4O4) {center_dot} 2.5H2O (2), and Zn4(H2O)2(C2H2N3)4(C8H4O4)2 {center_dot} 14H2O (3). Their crystal structures were determined by single-crystal X-ray diffraction. Their thermal properties were examined by thermogravimetric analysis. Structure 1 crystallizes in the monoclinic P21/n space group with a = 10.192(2) {angstrom}, b = 17.764(4) {angstrom}, c = 24.437(5) {angstrom}, {beta} = 91.19(3){sup o}, and V = 4423.3(15) {angstrom}3. Structure 2 crystallizes in the triclinic P space group with a = 7.797(2) {angstrom}, b = 10.047(2) {angstrom}, c = 13.577(3) {angstrom}, {alpha} = 110.18(3){sup o}, {beta} = 105.46(3){sup o}, {gamma} = 93.90(3){sup o}, and V = 947.0(3) {angstrom}3. Structure 3 crystallizes in monoclinic P21/n space group with a = 13.475(3) {angstrom}, b = 26.949(5) {angstrom}, c = 13.509(3) {angstrom}, {beta} = 95.18(3){sup o}, and V = 4885.7(17) {angstrom}3. In structure 1, the units of the triazole-Zn polyhedra are linked by BDC in a zigzag fashion to create the stacking of phenyl groups along the a axis. In structure 2, both triazole and BDC bridge Zn polyhedra in the (011) plane, resulting in the eight-membered channels along the a axis. In the case of structure 3, the BDC links the Zn polyhedra along the b axis to form a pillared open framework. This structure is the most porous of the compounds presented in this work.

  8. Modeling Cu Migration in CdTe Solar Cells Under Device-Processing and Long-Term Stability Conditions: Preprint

    SciTech Connect (OSTI)

    Teeter, G.; Asher, S.

    2008-05-01

    An impurity migration model for systems with material interfaces is applied to Cu migration in CdTe solar cells. In the model, diffusion fluxes are calculated from the Cu chemical potential gradient. Inputs to the model include Cu diffusivities, solubilities, and segregation enthalpies in CdTe, CdS and contact materials. The model yields transient and equilibrium Cu distributions in CdTe devices during device processing and under field-deployed conditions. Preliminary results for Cu migration in CdTe photovoltaic devices using available diffusivity and solubility data from the literature show that Cu segregates in the CdS, a phenomenon that is commonly observed in devices after back-contact processing and/or stress conditions.

  9. Comparison of Minority Carrier Lifetime Measurements in Superstrate and Substrate CdTe PV Devices: Preprint

    SciTech Connect (OSTI)

    Gessert, T. A.; Dhere, R. G.; Duenow, J. N.; Kuciauskas, D.; Kanevce, A.; Bergeson, J. D.

    2011-07-01

    We discuss typical and alternative procedures to analyze time-resolved photoluminescence (TRPL) measurements of minority carrier lifetime (MCL) with the hope of enhancing our understanding of how this technique may be used to better analyze CdTe photovoltaic (PV) device functionality. Historically, TRPL measurements of the fast recombination rate (t1) have provided insightful correlation with broad device functionality. However, we have more recently found that t1 does not correlate as well with smaller changes in device performance, nor does it correlate well with performance differences observed between superstrate and substrate CdTe PV devices. This study presents TRPL data for both superstrate and substrate CdTe devices where both t1 and the slower TRPL decay (t2) are analyzed. The study shows that changes in performance expected from small changes in device processing may correlate better with t2. Numerical modeling further suggests that, for devices that are expected to have similar drift field in the depletion region, effects of changes in bulk MCL and interface recombination should be more pronounced in t2. Although this technique may provide future guidance to improving CdS/CdTe device performance, it is often difficult to extract statistically precise values for t2, and therefore t2 data may demonstrate significant scatter when correlated with performance parameters.

  10. Static atomic displacements in a CdTe epitaxial layer on a GaAs substrate

    SciTech Connect (OSTI)

    Horning, R.D.; Staudenmann, J.

    1987-05-25

    A (001)CdTe epitaxial layer on a (001)GaAs substrate was studied by x-ray diffraction between 10 and 360 K. The CdTe growth took place at 380 /sup 0/C in a vertical gas flow metalorganic chemical vapor deposition reactor. Lattice parameters and integrated intensities of both the substrate and the epitaxial layer using the (00l) and (hhh) Bragg reflections reveal three important features. Firstly, the GaAs substrate does not exhibit severe strain after deposition and it is as perfect as a bulk GaAs. Secondly, the CdTe unit cell distorts tetragonally with a/sub perpendicular/>a/sub parallel/ below 300 K. The decay of the (00l) reflection intensities as a function of the temperature yields a Debye temperature of 142 K, the same value as for bulk CdTe. Thirdly, a temperature-dependent isotropic static displacement of the Cd and the Te atoms is introduced to account for the anomalous behavior of the (hhh) intensities.

  11. Investigation of nanocrystalline CdS/Si diode using complex impedance spectroscopy

    SciTech Connect (OSTI)

    El-Gendy, Y.A.; Umm Al-Qura University, University college, Physics Department, Alqunfoza ; Yahia, I.S.; Yakuphanoglu, F.

    2012-11-15

    Highlights: ? CdS/n-Si device was fabricated as a heterostructure. ? AFM was used to examine the structure of CdS/n-Si. ? Complex impedance Z?and Z?were calculated. ? AC conductivity was explained by the power law relation. ? CBH model was used to describe the AC conduction mechanism. -- Abstract: CdS/n-Si device was fabricated via depositing CdS thin film onto pre-cleaned n-silicon substrates. The atomic force microscope was used to examine the crystal size of the deposited films and its roughness. The AC conductivity and the real part of complex impedance Z?as a function of frequency at different temperatures were studied. The AC conductivity dependence of the applied frequency was explained on the basis of the power law relation. The bulk resistance has been calculated at different temperatures from the complex impedance Z?. The temperature dependence of capacitance for CdS/n-Si device at different frequencies was also investigated.

  12. Single-step in-situ synthesis and optical properties of ZnSe nanostructured dielectric nanocomposites

    SciTech Connect (OSTI)

    Dey, Chirantan; Rahaman Molla, Atiar; Tarafder, Anal; Karmakar, Basudeb; Kr Mishra, Manish; De, Goutam; Goswami, Madhumita; Kothiyal, G. P.

    2014-04-07

    This work provides the evidence of visible red photoluminescent light emission from ZnSe nanocrystals (NCs) grown within a dielectric (borosilicate glass) matrix synthesized by a single step in-situ technique for the first time and the NC sizes were controlled by varying only the concentration of ZnSe in glass matrix. The ZnSe NCs were investigated by UV-Vis optical absorption spectroscopy, Raman spectroscopy, and transmission electron microscopy (TEM). The sizes of the ZnSe NCs estimated from the TEM images are found to alter in the range of 2–53 nm. Their smaller sizes of the NCs were also calculated by using the optical absorption spectra and the effective mass approximation model. The band gap enlargements both for carrier and exciton confinements were evaluated and found to be changed in the range of 0–1.0 eV. The Raman spectroscopic studies showed blue shifted Raman peaks of ZnSe at 295 and 315 cm{sup −1} indicating phonon confinement effect as well as compressive stress effect on the surface atoms of the NCs. Red photoluminescence in ZnSe-glass nanocomposite reveals a broad multiple-peak structure due to overlapping of emission from NC size related electron-hole recombination (∼707 nm) and emissions from defects to traps, which were formed due to Se and Zn vacancies signifying potential application in photonics.

  13. Inversed relationship between CD44 variant and c-Myc due to oxidative stress-induced canonical Wnt activation

    SciTech Connect (OSTI)

    Yoshida, Go J. Saya, Hideyuki

    2014-01-10

    Highlights: CD44 variant810 and c-Myc are inversely expressed in gastric cancer cells. Redox-stress enhances c-Myc expression via canonical Wnt signal. CD44v, but not CD44 standard, suppresses redox stress-induced Wnt activation. CD44v expression promotes both transcription and proteasome degradation of c-Myc. Inversed expression pattern between CD44v and c-Myc is often recognized in vivo. -- Abstract: Cancer stem-like cells express high amount of CD44 variant8-10 which protects cancer cells from redox stress. We have demonstrated by immunohistochemical analysis and Western blotting, and reverse-transcription polymerase chain reaction, that CD44 variant8-10 and c-Myc tend to show the inversed expression manner in gastric cancer cells. That is attributable to the oxidative stress-induced canonical Wnt activation, and furthermore, the up-regulation of the downstream molecules, one of which is oncogenic c-Myc, is not easily to occur in CD44 variant-positive cancer cells. We have also found out that CD44v8-10 expression is associated with the turn-over of the c-Myc with the experiments using gastric cancer cell lines. This cannot be simply explained by the model of oxidative stress-induced Wnt activation. CD44v8-10-positive cancer cells are enriched at the invasive front. Tumor tissue at the invasive area is considered to be composed of heterogeneous cellular population; dormant cancer stem-like cells with CD44v8-10 {sup high}/ Fbw7 {sup high}/ c-Myc {sup low} and proliferative cancer stem-like cells with CD44v8-10 {sup high}/ Fbw7 {sup low}/ c-Myc {sup high}.

  14. Synthesis of monodispersed ZnAl{sub 2}O{sub 4} nanoparticles and their tribology properties as lubricant additives

    SciTech Connect (OSTI)

    Song, Xiaoyun; Zheng, Shaohua; Zhang, Jun; Li, Wei; Chen, Qiang; Cao, Bingqiang

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ? The preparation of ZnAl{sub 2}O{sub 4} nanoparticles was realized by hydrothermal method. ? After surface modification, ZnAl{sub 2}O{sub 4} nanoparticles of narrow size distribution can disperse in lubricating oil stably. ? The modified ZnAl{sub 2}O{sub 4} nanoparticles as lubricating oil additives exhibit good tribology properties. -- Abstract: Monodispersed spherical zinc aluminate spinel (ZnAl{sub 2}O{sub 4}) nanoparticles were synthesized via a solvothermal method and modified by oleic acid in cyclohexanol solution. The nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and infrared spectrum (IR). The dispersion ability of nanoparticles in lubricant oil was measured with optical absorbance spectrum. The results show that the modified nanoparticles are nearly monodispersed and can stably disperse in lubricant oil. The tribological properties of the ZnAl{sub 2}O{sub 4} nanoparticles as an additive in lubricant oil were evaluated with four-ball test and thrust-ring test. For comparison, ZnO and Al{sub 2}O{sub 3} nanoparticles as additive in lubricant oil were also tested respectively. The results show that ZnAl{sub 2}O{sub 4} nanoparticles exhibit better tribology properties in terms of anti-wear and anti-friction than ZnO or Al{sub 2}O{sub 3} nanoparticles. The anti-friction and anti-wear mechanisms were discussed and the lubricating effect of ZnAl{sub 2}O{sub 4} nanoparticles can be attributed to nano-bearings effect and tribo-sintering mechanism.

  15. The Effect Of ZnO Addition On Co/C Catalyst For Vapor And Aqueous Phase Reforming Of Ethanol

    SciTech Connect (OSTI)

    Davidson, Stephen; Sun, Junming; Hong, Yongchun; Karim, Ayman M.; Datye, Abhaya K.; Wang, Yong

    2014-02-05

    The effect of ZnO addition on the oxidation behavior of Co along with catalytic performance in vapor and aqueous phase reforming of ethanol were investigated on Co supported on carbon black (XC-72R). Carbon was selected to minimize the support interactions. Effect of ZnO addition during both vapor and aqueous phase reforming were compared at 250 °C. ZnO addition inhibited the reduction of cobalt oxides by H2 and created surface sites for H2O activation. During vapor phase reforming at 450 °C the redox of cobalt, driven by steam oxidation and H2 reduction, trended to an equilibrium of Co0/Co2+. ZnO showed no significant effect on cobalt oxidation, inferred from the minor changes of C1 product yield. Surface sites created by ZnO addition enhanced water activation and oxidation of surface carbon species, increasing CO2 selectivity. At 250 °C cobalt reduction was minimal, in situ XANES demonstrated that ZnO addition significantly facilitated oxidation of Co0 under vapor phase reforming conditions, demonstrated by lower C1 product yield. Sites introduced by ZnO addition improved the COx selectivity at 250 °C. Both Co/C and Co-ZnO/C rapidly oxidized under aqueous phase reaction conditions at 250 °C, showing negligible activity in aqueous phase reforming. This work suggests that ZnO affects the activation of H2O for Co catalysts in ethanol reforming.

  16. Synthesis and anion exchange properties of a Zn/Ni double hydroxide salt with a guarinoite structure

    SciTech Connect (OSTI)

    Delorme, F.; Seron, A.; Licheron, M.; Veron, E.; Giovannelli, F.; Beny, C.; Jean-Prost, V.; Martineau, D.

    2009-09-15

    In this study, the first route to synthesize a compound with the guarinoite structure (Zn,Co,Ni){sub 6}(SO{sub 4})(OH,Cl){sub 10}.5H{sub 2}O is reported. Zn/Ni guarinoite is obtained from the reaction of NiSO{sub 4}.7H{sub 2}O with solid ZnO in aqueous solution. The resulting green Zn/Ni guarinoite ((Zn{sub 3.52}Ni{sub 1.63})(SO{sub 4}){sub 1.33}(OH{sub 7.64}).4.67H{sub 2}O) was characterized by X-ray diffraction, infrared spectrometry, UV-Visible spectrometry and thermal analysis. It is shown that its structure is similar to the one described for the layered Zn sulfate hydroxide hydrate, i.e. brucite layers with 1/4 empty octahedra presenting tetrahedrally coordinated divalent atoms above and below the empty octahedra. Ni atoms are located in the octahedra and zinc atoms in tetrahedra and octahedra. In this structure the exchangeable anions are located at the apex of tetrahedra. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations show that the Zn/Ni guarinoite is composed of aggregates of hexagonal plates of several hundreds of nanometers. Due to its interest for industrial or environmental applications, the exchange of sulfate groups by carbonates has been investigated. Results show a limited exchange and a higher affinity of the Zn/Ni guarinoite for sulfates compared to carbonates. - Graphical abstract: SEM micrograph (secondary electrons) of the synthesized Zn/Ni guarinoite showing that aggregates are composed of small plate-like particles.

  17. Photocatalytic pure water splitting activities for ZnGa{sub 2}O{sub 4} synthesized by various methods

    SciTech Connect (OSTI)

    Zeng, Chunmei; Hu, Tao; Hou, Nianjun; Liu, Siyao; Gao, Wenliang; Cong, Rihong; Yang, Tao

    2015-01-15

    Highlights: High temperature solid state reaction, hydrothermal, sol-gel methods were applied. All ZnGa{sub 2}O{sub 4} samples show UV-light catalytic activities on pure water splitting. Bulk ZnGa{sub 2}O{sub 4} has a good photocatalytic activity per specific surface area. Sol-gel is a superior method to prepare nanosized ZnGa{sub 2}O{sub 4} with a high activity. The AQY for SG-ZnGa{sub 2}O{sub 4} is 2.6% for pure water splitting under 313 nm irradiation. - Abstract: We studied and compared the photocatalytic water splitting performances for ZnGa{sub 2}O{sub 4} prepared by high temperature solid state reaction (HTSSR), hydrothermal (HY) and sol-gel (SG) methods. HTSSR-ZnGa{sub 2}O{sub 4} has a relative large photocatalytic activity per surface area (1.6 ?mol/h/m{sup 2}) in pure water by UV irradiation due to its high crystallinity. The HY- and SG-samples both have small particle sizes (20?30 nm) and therefore high surface area (20 and 29 m{sup 2}/g, respectively), which leads to superior photocatalytic H{sub 2} evolution rates per unit mass (11.5 and 28.5 ?mol/h/g). The apparent quantum yield of SG-ZnGa{sub 2}O{sub 4} for pure water splitting under 313 nm irradiation is 2.6%. The existence of substantial surface defects is the major problem for HY- and SG-ZnGa{sub 2}O{sub 4}. Consequently, the usage of sacrificial agents could greatly enhance the activities and indeed the H{sub 2} evolution rates in 20 Vol. % methanol aqueous solution increase to 100 and 142 ?mol/h/g for HY- and SG-ZnGa{sub 2}O{sub 4}, respectively.

  18. Dielectric properties of a polar ZnSnO{sub 3} with LiNbO{sub 3}-type

    Office of Scientific and Technical Information (OSTI)

    structure (Journal Article) | SciTech Connect Dielectric properties of a polar ZnSnO{sub 3} with LiNbO{sub 3}-type structure Citation Details In-Document Search Title: Dielectric properties of a polar ZnSnO{sub 3} with LiNbO{sub 3}-type structure The dielectric properties of a polar LiNbO{sub 3}-type ZnSnO{sub 3} synthesized under high-pressure have been investigated with respect to the dielectric permittivity in the relative low frequency range of 10 kHz to 1 MHz and the SHG response at an

  19. Zn-Doping Dependence of Stripe Order in La1.905Ba0.095CuO4

    SciTech Connect (OSTI)

    Hucker, M.; Zimmermann, M.v.; Xu, Z.J.; Wen, J.S.; Gu, G.D.; Tian, W.; Zarestky, J.; Tranquada, J.M.

    2011-04-01

    The effect of Zn-doping on the stripe order in La{sub 1.905}Ba{sub 0.095}CuO{sub 4} has been studied by means of x-ray and neutron diffraction as well as magnetization measurements. While 1% Zn leads to an increase of the spin stripe order, it unexpectedly causes a wipe out of the visibility of the charge stripe order. A magnetic field of 10 Tesla applied along the c-axis has no reversing effect on the charge order. We compare this observation with the Zn-doping dependence of the crystal structure, superconductivity, and normal state magnetism.

  20. Zn-doped and undoped SnO{sub 2} nanoparticles: A comparative structural, optical and LPG sensing properties study

    SciTech Connect (OSTI)

    Mishra, R.K.; Sahay, P.P.

    2012-12-15

    Graphical abstract: The X-ray diffraction (XRD) analyses confirm that all the materials prepared are polycrystalline SnO{sub 2} possessing tetragonal rutile structure. On Zn-doping, the crystallite size has been found to decrease from 25 nm (undoped sample) to 13 nm (1 at% Zn-doped sample). Display Omitted Highlights: ? Zn-doped SnO{sub 2} nanoparticles show smaller crystallite size (1117 nm). ? Optical band gap in SnO{sub 2} nanoparticles increases on Zn-doping. ? 2 at% Zn-doped sample show minimum room temperature resistivity. ? LPG response of the Zn-doped SnO{sub 2} nanoparticles increases considerably. ? 1 at% Zn-doped sample shows maximum response (87%) at 300 C to 1 vol% concentration. -- Abstract: SnO{sub 2} nanoparticles were prepared by the co-precipitation method with SnCl{sub 4}5H{sub 2}O as the starting material and Zn(CH{sub 3}COO){sub 2}2H{sub 2}O as the source of dopant. All the materials prepared have been found to be polycrystalline SnO{sub 2} possessing tetragonal rutile structure with crystallite sizes in the range 1125 nm. Optical analyses reveal that for the SnO{sub 2} nanoparticles, both undoped and Zn-doped, direct transition occurs with the bandgap energies in the range 3.053.41 eV. Variation in the room temperature resistivity of the SnO{sub 2} nanoparticles as a function of dopant concentration has been explained on the basis of two competitive processes: (i) replacement of Sn{sup 4+} ion by an added Zn{sup 2+} ion, and (ii) ionic compensation of Zn{sup 2+} by the formation of oxygen vacancies. Among all the samples examined for LPG sensing, the 1 at% Zn-doped sample exhibits fast and maximum response (?87%) at 300 C for 1 vol% concentration of LPG in air.

  1. Role of polycrystallinity in CdTe and CuInSe sub 2 photovoltaic cells

    SciTech Connect (OSTI)

    Sites, J.R. )

    1991-01-01

    The polycrystalline nature of thin-film CdTe and CuInSe{sub 2} solar cells continues to be a major factor in several individual losses that limit overall cell efficiency. This report describes progress in the quantitative separation of these losses, including both measurement and analysis procedures. It also applies these techniques to several individual cells to help document the overall progress with CdTe and CuInSe{sub 2} cells. Notably, CdTe cells from Photon Energy have reduced window photocurrent losses to 1 mA/Cm{sup 2}; those from the University of South Florida have achieved a maximum power voltage of 693 mV; and CuInSe{sub 2} cells from International Solar Electric Technology have shown a hole density as high as 7 {times} 10{sup 16} cm{sup {minus}3}, implying a significant reduction in compensation. 9 refs.

  2. Toroidally Asymmetric Distributions of Hydrocarbon (CD) Emission and Chemical Sputtering Sources in DIII-D

    SciTech Connect (OSTI)

    Groth, M; Brooks, N H; Fenstermacher, M E; Lasnier, C J; McLean, A G; Watkins, J G

    2006-05-16

    Measurements in DIII-D show that the carbon chemical sputtering sources along the inner divertor and center post are toroidally periodic and highest at the upstream tile edge. Imaging with a tangentially viewing camera and visible spectroscopy were used to monitor the emission from molecular hydrocarbons (CH/CD) at 430.8 nm and deuterium neutrals in attached and partially detached divertors of low-confinement mode plasmas. In contrast to the toroidally periodic CD distribution, emission from deuterium neutrals was observed to be toroidally symmetric along the inner strike zone. The toroidal distribution of the measured tile surface temperature in the inner divertor correlates with that of the CD emission, suggesting larger parallel particle and heat fluxes to the upstream tile edge, either due to toroidal tile gaps or height steps between adjacent tiles.

  3. Structural and electrical properties of TiO{sub 2}/ZnO core–shell nanoparticles synthesized by hydrothermal method

    SciTech Connect (OSTI)

    Vlazan, P.; Ursu, D.H.; Irina-Moisescu, C.; Miron, I.; Sfirloaga, P.; Rusu, E.

    2015-03-15

    TiO{sub 2}/ZnO core–shell nanoparticles were successfully synthesized by hydrothermal method in two stages: first stage is the hydrothermal synthesis of ZnO nanoparticles and second stage the obtained ZnO nanoparticles are encapsulated in TiO{sub 2}. The obtained ZnO, TiO{sub 2} and TiO{sub 2}/ZnO core–shell nanoparticles were investigated by means of X-ray diffraction, transmission electron microscopy, Brunauer, Emmett, Teller and resistance measurements. X-ray diffraction analysis revealed the presence of both, TiO{sub 2} and ZnO phases in TiO{sub 2}/ZnO core–shell nanoparticles. According to transmission electron microscopy images, ZnO nanoparticles have hexagonal shapes, TiO{sub 2} nanoparticles have a spherical shape, and TiO{sub 2}/ZnO core–shell nanoparticles present agglomerates and the shape of particles is not well defined. The activation energy of TiO{sub 2}/ZnO core–shell nanoparticles was about 101 meV. - Graphical abstract: Display Omitted - Highlights: • TiO{sub 2}/ZnO core–shell nanoparticles were synthesized by hydrothermal method. • TiO{sub 2}/ZnO core–shell nanoparticles were investigated by means of XRD, TEM and BET. • Electrical properties of TiO{sub 2}/ZnO core–shell nanoparticles were investigated. • The activation energy of TiO{sub 2}/ZnO core–shell nanoparticles was about E{sub a} = 101 meV.

  4. Emission switching in carbon dots coated CdTe quantum dots driving by pH

    Office of Scientific and Technical Information (OSTI)

    dependent hetero-interactions (Journal Article) | SciTech Connect Emission switching in carbon dots coated CdTe quantum dots driving by pH dependent hetero-interactions Citation Details In-Document Search Title: Emission switching in carbon dots coated CdTe quantum dots driving by pH dependent hetero-interactions Due to the different emission mechanism between fluorescent carbon dots and semiconductor quantum dots (QDs), it is of interest to explore the potential emission in

  5. Intrinsic Surface Passivation of CdTe (Journal Article) | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Intrinsic Surface Passivation of CdTe Citation Details In-Document Search Title: Intrinsic Surface Passivation of CdTe Authors: Reese, Matthew O. ; Perkins, Craig L. ; Burst, James M. ; Farrell, Stuart ; Barnes, Teresa M. ; Johnston, Steve W. ; Kuciauskas, Darius ; Gessert, Timothy A. ; Metzger, Wyatt K. Publication Date: 2015-10-21 OSTI Identifier: 1225933 Report Number(s): NREL/JA-5K00-64478 Journal ID: ISSN 0021-8979 DOE Contract Number: AC36-08GO28308 Resource Type: Journal Article Resource

  6. Optimal packing size of non-ligated CdSe nanoclusters for microstructure synthesis

    SciTech Connect (OSTI)

    Tefera, Anteneh G.; Mochena, Mogus D.; Johnson, Elijah; Dickerson, James

    2014-09-14

    Structural and electrostatic properties of nanoclusters of CdSe of diameter 1–2 nm are studied with first principle calculations to determine the optimal size for synthesizing microstructures. Based on robustness of the core structure, i.e., the retention of tetrahedral geometry, hexagonal ring structure, and overall wu{sup ¨}rtzite structure to surface relaxations, we conclude that nanoclusters of ~2 nm diameter are the best candidates to form a dense microstructure with minimal interstitial space. Se-terminated surfaces retain a zigzag structure as Se atoms are pulled out and Cd atoms are pulled in due to relaxation, therefore, are best suited for inter-nanocluster formations.

  7. Small-Molecule CD4-Mimics: Structure-Based Optimization of HIV-1 Entry

    Office of Scientific and Technical Information (OSTI)

    Inhibition (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Small-Molecule CD4-Mimics: Structure-Based Optimization of HIV-1 Entry Inhibition Citation Details In-Document Search Title: Small-Molecule CD4-Mimics: Structure-Based Optimization of HIV-1 Entry Inhibition Authors: Melillo, Bruno ; Liang, Shuaiyi ; Park, Jongwoo ; Schön, Arne ; Courter, Joel R. ; LaLonde, Judith M. ; Wendler, Daniel J. ; Princiotto, Amy M. ; Seaman, Michael S. ; Freire, Ernesto ;

  8. Director's CD-3b Readiness Review of the MINERvA Project

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    3b Readiness Review of the MINERvA Project Main INjector ExpeRiment v-A June 11, 2007 | Overview | CD-3b Documentation| Other Documents| Link to the Directorate Web Page for this Review Overview of Charge and Experiment MINERvA Overview (pdf) Review Agenda (pdf) Review Charge (pdf) DOE CD-3b Scorecard (pdf with links) Review Presentations by MINERvA Project Team Project Overview (pdf) Scintillators (WBS 1.0) WLS Fibers (WBS 2.0) and Clear Fiber Cables (WBS 4.0) (pdf) Phototubes (WBS 6.0) PMT

  9. Visible Light Photocatalysis via CdS/TiO2Nanocomposite Materials

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Srinivasan, Sesha S.; Wade, Jeremy; Stefanakos, Elias K.

    2006-01-01

    Nanostructured colloidal semiconductors with heterogeneous photocatalytic behavior have drawn considerable attention over the past few years. This is due to their large surface area, high redox potential of the photogenerated charge carriers, and selective reduction/oxidation of different classes of organic compounds. In the present paper, we have carried out a systematic synthesis of nanostructured CdS-TiO2via reverse micelle process. The structural and microstructural characterizations of the as-prepared CdS-TiO2nanocomposites are determined using XRD and SEM-EDS techniques. The visible light assisted photocatalytic performance is monitored by means of degradation of phenol in water suspension.

  10. Direct Observation of Energy-Gap Scaling Law in CdSe Quantum Dots with Positrons

    SciTech Connect (OSTI)

    Denison, Arthur Blanchard; Weber, M. H.; Lynn, K. G.; Barbiellini, B.; Sterne, P. A.

    2002-07-01

    CdSe quantum dot samples with sizes in the range of 1.8~6 nm in diameter were examined by positron annihilation spectroscopy. The results were compared to data obtained for single-crystal bulk CdSe. Evidence is provided that the positrons annihilate within the nanospheres. The annihilation line shape shows a smearing at the boundary of the Jones zone proportional to the widening of the band gap due to a reduction in the size of the quantum dots. The data confirm that the change in the band gap is inversely proportional to the square of the quantum dot diameter.

  11. COLLOQUIUM: Functional capabilities and design of the ITER EC H&CD system |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Princeton Plasma Physics Lab 17, 2016, 4:15pm to 5:30pm Colloquia MBG Auditorium, PPPL (284 cap.) COLLOQUIUM: Functional capabilities and design of the ITER EC H&CD system Dr. Mark Henderson ITER Organization A 24MW Electron Cyclotron (EC) system operating at 170 GHz and 3600 s pulse length is to be installed on ITER. The EC plant shall deliver 20MW of this power to the plasma for Heating and Current Drive (H&CD) applications. The EC system is designed for plasma initiation, central

  12. Neutrino-nucleus scattering of {sup 95,97}Mo and {sup 116}Cd

    SciTech Connect (OSTI)

    Ydrefors, E.; Almosly, W.; Suhonen, J.

    2013-12-30

    Accurate knowledge about the nuclear responses to supernova neutrinos for relevant nuclear targets is important both for neutrino detection and for astrophysical applications. In this paper we discuss the cross sections for the charged-current neutrino-nucleus scatterings off {sup 95,97}Mo and {sup 116}Cd. The microscopic quasiparticle-phonon model is adopted for the odd-even nuclei {sup 95,97}Mo. In the case of {sup 116}Cd we present cross sections both for the Bonn one-boson-exchange potential and self-consistent calculations based on modern Skyrme interactions.

  13. Preparation and physical properties of antiperovskite-type compounds CdNCo{sub 3-z}Ni{sub z} (0{<=}z{<=}3)

    SciTech Connect (OSTI)

    He Bing; Dong Cheng; Yang Lihong; Ge Linhui; Chen Hong

    2011-08-15

    A series of CdNCo{sub 3-z}Ni{sub z} (0{<=}z{<=}3) samples were prepared from CdO and metal powders under NH{sub 3} atmosphere at 743 K. The structural and physical properties were investigated by means of X-ray powder diffraction, temperature dependent resistivity and magnetic measurements. X-ray powder diffraction results show that CdNCo{sub 3} is a new ternary nitride with antiperovskite structure, and it can form a complete solid solution series with CdNNi{sub 3}. Both CdNCo{sub 3} and CdNNi{sub 3} samples show metallic temperature dependent resistivity and exhibit a Fermi liquid behavior below 50 K. All samples are ferromagnetic, and their coercivity and remanence decrease as the Ni content increases. The temperature dependence of the magnetization of the CdNCo{sub 3-z}Ni{sub z} samples can be well fitted to the combination of a Bloch term and a Curie-Weiss term. The CdNCo{sub 3} sample is ferromagnet with coercivity of 240 Oe at room-temperature. In contrast to the paramagnetism previously reported, our CdNNi{sub 3} sample exhibits very soft and weak ferromagnetism. - Graphical Abstract: CdNCo{sub 3} is a new ternary nitride with antiperovskite structure, and it can form a complete solid solution series with CdNNi{sub 3}. Highlights: > CdNCo{sub 3-z}Ni{sub z} (0{<=}z{<=}3) samples were synthesized by solid-gas reactions. > CdNCo{sub 3} is a new ternary antiperovskite nitride, and it can form a complete solid solution series with CdNNi{sub 3}. > Both CdNCo{sub 3} and CdNNi{sub 3} samples show metallic behavior and exhibit a Fermi liquid behavior below 50 K. > Magnetic measurements show that CdNCo{sub 3} and CdNNi{sub 3} exhibit ferromagnetic and weak ferromagnetic behavior, respectively.

  14. Morphology, electrical, and optical properties of heavily doped ZnTe:Cu thin films

    SciTech Connect (OSTI)

    El Akkad, Fikry; Abdulraheem, Yaser

    2013-11-14

    We report on a study of the physical properties of ZnTe:Cu films with Cu content up to ∼12 at. % prepared using rf magnetron sputtering. The composition and lateral homogeneities are studied using X-ray photoelectron spectroscopy (XPS). Atomic force microscopy measurements on films deposited at different substrate temperatures (up to 325 °C) yielded activation energy of 12 kJ/mole for the grains growth. The results of XPS and electrical and optical measurements provide evidence for the formation of the ternary zinc copper telluride alloy in films containing Cu concentration above ∼4 at. %. The XPS results suggest that copper is incorporated in the alloy with oxidation state Cu{sup 1+} so that the alloy formula can be written Zn{sub 1−y}Cu{sub y} Te with y = 2−x, where x is a parameter measuring the stoichiometry in the Cu site. The formation of this alloy causes appreciable shift in the binding energies of the XPS peaks besides an IR shift in the energy band gap. Detailed analysis of the optical absorption data revealed the presence of two additional transitions, besides the band gap one, originating from the Γ{sub 8} and Γ{sub 7} (spin-orbit) valence bands to a donor level at ∼0.34 eV below the Γ{sub 6} conduction band. This interpretation yields a value for the valence band splitting energy Δ≅ 0.87 eV independent of copper concentration. On the other hand, the mechanism of formation of the alloy is tentatively explained in terms of a point defect reaction in which substitutional Cu defect Cu{sub Zn} is also created. Assuming that substitutional Cu is the dominant acceptor in the Zn rich alloy as in ZnTe, its formation energy was determined to be 1.7 eV close to the theoretical value (1.41 eV) in ZnTe.

  15. Comment on 'The diatomic dication CuZn{sup 2+} in the gas phase' [J. Chem. Phys. 135, 034306 (2011)

    SciTech Connect (OSTI)

    Fiser, Jiri; Diez, Reinaldo Pis; Franzreb, Klaus; Alonso, Julio A.

    2013-02-21

    In this Comment, the density functional theory (DFT) calculations carried out by Diez et al. [J. Chem. Phys. 135, 034306 (2011)] are revised within the framework of the coupled-cluster single double triple method. These more sophisticated calculations allow us to show that the {sup 2}{Sigma}{sup +} electronic ground state of CuZn{sup 2+}, characterized as the metastable ground state by DFT calculations, is a repulsive state instead. The {sup 2}{Delta} and {sup 2}{Pi} metastable states of CuZn{sup 2+}, on the other hand, should be responsible for the formation mechanism of the dication through the near-resonant electron transfer CuZn{sup +}+ Ar{sup +}{yields} CuZn{sup 2+}+ Ar reaction.

  16. Physical deoxygenation of graphene oxide paper surface and facile in situ synthesis of graphene based ZnO films

    SciTech Connect (OSTI)

    Ding, Jijun; Wang, Minqiang Zhang, Xiangyu; Ran, Chenxin; Shao, Jinyou; Ding, Yucheng

    2014-12-08

    In-situ sputtering ZnO films on graphene oxide (GO) paper are used to fabricate graphene based ZnO films. Crystal structure and surface chemical states are investigated. Results indicated that GO paper can be effectively deoxygenated by in-situ sputtering ZnO on them without adding any reducing agent. Based on the principle of radio frequency magnetron sputtering, we propose that during magnetron sputtering process, plasma streams contain large numbers of electrons. These electrons not only collide with argon atoms to produce secondary electrons but also they are accelerated to bombard the substrates (GO paper) resulting in effective deoxygenation of oxygen-containing functional groups. In-situ sputtering ZnO films on GO paper provide an approach to design graphene-semiconductor nanocomposites.

  17. Dielectric properties of a polar ZnSnO{sub 3} with LiNbO{sub...

    Office of Scientific and Technical Information (OSTI)

    ZnSnOsub 3 exhibits the maximum SHG efficiency of approximately 50 times that of quartz. ... second harmonic generation (SHG) efficiency of approximately 50 times that of quartz. ...

  18. Charge transport properties of p-CdTe/n-CdTe/n{sup +}-Si diode-type nuclear radiation detectors based on metalorganic vapor-phase epitaxy-grown epilayers

    SciTech Connect (OSTI)

    Niraula, M.; Yasuda, K.; Wajima, Y.; Yamashita, H.; Tsukamoto, Y.; Suzuki, Y.; Matsumoto, M.; Takai, N.; Tsukamoto, Y.; Agata, Y.

    2013-10-28

    Charge transport properties of p-CdTe/n-CdTe/n{sup +}-Si diode-type nuclear radiation detectors, fabricated by growing p-and n-type CdTe epilayers on (211) n{sup +}-Si substrates using metalorganic vapor-phase epitaxy (MOVPE), were studied by analyzing current-voltage characteristics measured at various temperatures. The diode fabricated shows good rectification properties, however, both forward and reverse biased currents deviate from their ideal behavior. The forward current exhibits typical feature of multi-step tunneling at lower biases; however, becomes space charge limited type when the bias is increased. On the other hand, the reverse current exhibits thermally activated tunneling-type current. It was found that trapping centers at the p-CdTe/n-CdTe junction, which were formed due to the growth induced defects, determine the currents of this diode, and hence limit the performance of the nuclear radiation detectors developed.

  19. Interactions of aqueous amino acids and proteins with the (110) surface of ZnS in molecular dynamics simulations

    SciTech Connect (OSTI)

    Nawrocki, Grzegorz; Cieplak, Marek

    2014-03-07

    The growing usage of nanoparticles of zinc sulfide as quantum dots and biosensors calls for a theoretical assessment of interactions of ZnS with biomolecules. We employ the molecular-dynamics-based umbrella sampling method to determine potentials of mean force for 20 single amino acids near the ZnS (110) surface in aqueous solutions. We find that five amino acids do not bind at all and the binding energy of the remaining amino acids does not exceed 4.3 kJ/mol. Such energies are comparable to those found for ZnO (and to hydrogen bonds in proteins) but the nature of the specificity is different. Cysteine can bind with ZnS in a covalent way, e.g., by forming the disulfide bond with S in the solid. If this effect is included within a model incorporating the Morse potential, then the potential well becomes much deeperthe binding energy is close to 98 kJ/mol. We then consider tryptophan cage, a protein of 20 residues, and characterize its events of adsorption to ZnS. We demonstrate the relevance of interactions between the amino acids in the selection of optimal adsorbed conformations and recognize the key role of cysteine in generation of lasting adsorption. We show that ZnS is more hydrophobic than ZnO and that the density profile of water is quite different than that forming near ZnOit has only a minor articulation into layers. Furthermore, the first layer of water is disordered and mobile.

  20. Id1 expression promotes peripheral CD4{sup +} T cell proliferation and survival upon TCR activation without co-stimulation

    SciTech Connect (OSTI)

    Liu, Chen; Jin, Rong; Wang, Hong-Cheng; Tang, Hui; Liu, Yuan-Feng; Qian, Xiao-Ping; Sun, Xiu-Yuan; Ge, Qing; Sun, Xiao-Hong; Zhang, Yu

    2013-06-21

    Highlights: •Id1 expression enables naïve T cell proliferation without anti-CD28 co-stimulation. •Id1 expression facilitates T cells survival when stimulated with anti-CD3. •Elevation of IL-2 production by Id1 contributes increased proliferation and survival. •Id1 potentiates NF-κB activation by anti-CD3 stimulation. -- Abstract: Although the role of E proteins in the thymocyte development is well documented, much less is known about their function in peripheral T cells. Here we demonstrated that CD4 promoter-driven transgenic expression of Id1, a naturally occurring dominant-negative inhibitor of E proteins, can substitute for the co-stimulatory signal delivered by CD28 to facilitate the proliferation and survival of naïve CD4{sup +} cells upon anti-CD3 stimulation. We next discovered that IL-2 production and NF-κB activity after anti-CD3 stimulation were significantly elevated in Id1-expressing cells, which may be, at least in part, responsible for the augmentation of their proliferation and survival. Taken together, results from this study suggest an important role of E and Id proteins in peripheral T cell activation. The ability of Id proteins to by-pass co-stimulatory signals to enable T cell activation has significant implications in regulating T cell immunity.

  1. Synthesis of monodispersed CdSe nanocrystals in poly(styrene-alt-maleic anhydride) at room temperature

    SciTech Connect (OSTI)

    Liu, S.H.; Qian, X.F.; Yuan, J.Y.; Yin, J.; He, R.; Zhu, Z.K

    2003-07-14

    Nanocomposite of CdSe/poly(styrene-alt-maleic anhydride) (PSM) was successfully prepared via an in situ reaction process at room temperature and ambient pressure. Transmission electron microscopy (TEM) analysis revealed that CdSe nanoparticles with a small size and narrow size distribution were obtained. The obtained nanocomposite was also characterized by FT-IR, XRD, ultraviolet-visible, and fluorescence spectroscopy.

  2. High Resolution Dopant Profiles Revealed by Atom Probe Tomography and STEM-EBIC for CdTe Based Solar Cells

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Poplawsky, Jonathan D.; Li, Chen; Paudel, Naba; Guo, Wei; Yan, Yanfa; Pennycook, Stephen J.

    2016-01-01

    Segregated elements and their diffusion profiles within grain boundaries and interfaces resulting from post deposition heat treatments are revealed using atom probe tomography (APT), scanning transmission electron microscopy (STEM), and electron beam induced current (EBIC) techniques. The results demonstrate how these techniques complement each other to provide conclusive evidence for locations of space charge regions and mechanisms that create them at the nanoscale. Most importantly, a Cl dopant profile that extends ~5 nm into CdTe grains interfacing the CdS is shown using APT and STEM synergy, which has been shown to push the pn-junction into the CdTe layer indicative ofmore » a homojunction (revealed by STEM EBIC). In addition, Cu and Cl concentrations within grain boundaries within several nms and µms from the CdS/CdTe interface are compared, Na segregation of <0.1% is detected, and S variations of ~1–3% are witnessed between CdTe grains close to the CdS/CdTe interface. The segregation and diffusion of these elements directly impacts on the material properties, such as band gap energy and n/p type properties. Optimization of the interfacial and grain boundary doping will lead to higher efficiency solar cells.« less

  3. High Resolution Dopant Profiles Revealed by Atom Probe Tomography and STEM-EBIC for CdTe Based Solar Cells

    SciTech Connect (OSTI)

    Poplawsky, Jonathan D.; Li, Chen; Paudel, Naba; Guo, Wei; Yan, Yanfa; Pennycook, Stephen J.

    2016-01-01

    Segregated elements and their diffusion profiles within grain boundaries and interfaces resulting from post deposition heat treatments are revealed using atom probe tomography (APT), scanning transmission electron microscopy (STEM), and electron beam induced current (EBIC) techniques. The results demonstrate how these techniques complement each other to provide conclusive evidence for locations of space charge regions and mechanisms that create them at the nanoscale. Most importantly, a Cl dopant profile that extends ~5 nm into CdTe grains interfacing the CdS is shown using APT and STEM synergy, which has been shown to push the pn-junction into the CdTe layer indicative of a homojunction (revealed by STEM EBIC). In addition, Cu and Cl concentrations within grain boundaries within several nms and µms from the CdS/CdTe interface are compared, Na segregation of <0.1% is detected, and S variations of ~1–3% are witnessed between CdTe grains close to the CdS/CdTe interface. The segregation and diffusion of these elements directly impacts on the material properties, such as band gap energy and n/p type properties. Optimization of the interfacial and grain boundary doping will lead to higher efficiency solar cells.

  4. Prolactin receptor attenuation induces zinc pool redistribution through ZnT2 and decreases invasion in MDA-MB-453 breast cancer cells

    SciTech Connect (OSTI)

    Bostanci, Zeynep; Alam, Samina; Soybel, David I.; Kelleher, Shannon L.

    2014-02-15

    Prolactin receptor (PRL-R) activation regulates cell differentiation, proliferation, cell survival and motility of breast cells. Prolactin (PRL) and PRL-R over-expression are strongly implicated in breast cancer, particularly contributing to tumor growth and invasion in the more aggressive estrogen-receptor negative (ER?) disease. PRL-R antagonists have been suggested as potential therapeutic agents; however, mechanisms through which PRL-R antagonists exert their actions are not well-understood. Zinc (Zn) is a regulatory factor for over 10% of the proteome, regulating critical cell processes such as proliferation, cell signaling, transcription, apoptosis and autophagy. PRL-R signaling regulates Zn metabolism in breast cells. Herein we determined effects of PRL-R attenuation on cellular Zn metabolism and cell function in a model of ER-, PRL-R over-expressing breast cancer cells (MDA-MB-453). PRL-R attenuation post-transcriptionally increased ZnT2 abundance and redistributed intracellular Zn pools into lysosomes and mitochondria. ZnT2-mediated lysosomal Zn sequestration was associated with reduced matrix metalloproteinase 2 (MMP-2) activity and decreased invasion. ZnT2-mediated Zn accumulation in mitochondria was associated with increased mitochondrial oxidation. Our results suggest that PRL-R antagonism in PRL-R over-expressing breast cancer cells may reduce invasion through the redistribution of intracellular Zn pools critical for cellular function. - Highlights: PRL-R attenuation increased ZnT2 expression. PRL-R attenuation increased lysosomal and mitochondrial Zn accumulation. PRL-R attenuation decreased MMP-2 and invasion. PRL-R antagonists may modulate lysosomal and mitochondrial Zn pools.

  5. Defect-induced magnetism in cobalt-doped ZnO epilayers

    SciTech Connect (OSTI)

    Ciatto, G.; Fonda, E.; Trolio, A. Di; Alippi, P.; Varvaro, G.; Bonapasta, A. Amore; Polimeni, A.; Capizzi, M.

    2014-02-21

    We used a synergic Co-edge X-ray absorption spectroscopy (XAS) and density functional theory calculations approach to perform a study of defects which could account for the room temperature ferromagnetism of ZnCoO, an oxide of great potential interest in semiconductor spintronics. Our results suggest that a key role is played by specific defect complexes in which O vacancies are located close to the Co atoms. Extended defects such as Co clusters have a marginal function, although we observe their formation at the epilayer surface under certain growth conditions. We also show preliminary results of the study of hydrogen-induced defects in ZnCoO epilayers deliberately hydrogen irradiated via a Kaufman source. Hydrogen was in fact predicted to mediate a ferromagnetic spin-spin interaction between neighboring magnetic impurities.

  6. ZnO buffer layer for metal films on silicon substrates

    DOE Patents [OSTI]

    Ihlefeld, Jon

    2014-09-16

    Dramatic improvements in metallization integrity and electroceramic thin film performance can be achieved by the use of the ZnO buffer layer to minimize interfacial energy between metallization and adhesion layers. In particular, the invention provides a substrate metallization method utilizing a ZnO adhesion layer that has a high work of adhesion, which in turn enables processing under thermal budgets typically reserved for more exotic ceramic, single-crystal, or metal foil substrates. Embodiments of the present invention can be used in a broad range of applications beyond ferroelectric capacitors, including microelectromechanical systems, micro-printed heaters and sensors, and electrochemical energy storage, where integrity of metallized silicon to high temperatures is necessary.

  7. The magnetic ordering in high magnetoresistance Mn-doped ZnO thin films

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Venkatesh, S.; Baras, A.; Lee, J. -S.; Roqan, I. S.

    2016-03-24

    Here, we studied the nature of magnetic ordering in Mn-doped ZnO thin films that exhibited ferromagnetism at 300 K and superparamagnetism at 5 K. We directly inter-related the magnetisation and magnetoresistance by invoking the polaronpercolation theory and variable range of hopping conduction below the metal-to-insulator transition. By obtaining a qualitative agreement between these two models, we attribute the ferromagnetism to the s-d exchange-induced spin splitting that was indicated by large positive magnetoresistance (~40 %). Low temperature superparamagnetism was attributed to the localization of carriers and non-interacting polaron clusters. This analysis can assist in understanding the presence or absence of ferromagnetismmore » in doped/un-doped ZnO.« less

  8. Compositional and Structural Study of Gd Implanted ZnO Films

    SciTech Connect (OSTI)

    Murmu, Peter P.; Kennedy, John V.; Markwitz, Andreas; Ruck, Ben J.

    2009-07-23

    We report a compositional and structural study of ZnO films implanted with 30 keV Gd ions. The depth profile of the implanted ions, measured by Rutherford backscattering spectrometry, matches predictions of DYNAMIC-TRIM calculations. However, after annealing at temperatures above 550 deg. C the Gd ions are observed to migrate towards the bulk, and at the same time atomic force microscope images of the film surfaces show significant roughening. Raman spectroscopy shows that the annealed films have a reduced number of crystalline defects. The overall results are useful for developing an implantation-annealing regime to produce well characterized samples to investigate magnetism in the ZnO:Gd system.

  9. Density-functional Monte-Carlo simulation of CuZn order-disorder transition

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khan, Suffian N.; Eisenbach, Markus

    2016-01-25

    We perform a Wang-Landau Monte Carlo simulation of a Cu0.5Zn0.5 order-disorder transition using 250 atoms and pairwise atom swaps inside a 5 x 5 x 5 BCC supercell. Each time step uses energies calculated from density functional theory (DFT) via the all-electron Korringa-Kohn- Rostoker method and self-consistent potentials. Here we find CuZn undergoes a transition from a disordered A2 to an ordered B2 structure, as observed in experiment. Our calculated transition temperature is near 870 K, comparing favorably to the known experimental peak at 750 K. We also plot the entropy, temperature, specific-heat, and short-range order as a function ofmore » internal energy.« less

  10. Study on structural, optical properties of solvothermally synthesized Ni doped CdS nanorods

    SciTech Connect (OSTI)

    Kaur, Kamaldeep Verma, N. K.

    2015-05-15

    Undoped and alkali metal i.e Ni doped CdS nanorods (Cd{sub x}Ni{sub 1-x}S) with (x = 0.0, 0.3,) has been synthesized by using a convenient solvothermal technique. In order to confirm the structure of the synthesized nanorods X-ray diffraction (XRD) has been done which reveals the formation of hexagonal phase of the dilute magnetic semiconducting nanorods having size of undoped 27.79nm and doped 17.49nm. Energy dispersive X-ray analysis depicts the presence of elements Cd, Ni and S in their stoichiometric ratio. Optical behavior of undoped and doped nanorods has been investigated. UV-visible spectra show the blue shift in the band gap, as compared to the bulk CdS which may be due the quantum confinement occurs in the nanostructures. Morphological analysis has been done with the help of Transmission electron microscope which confirms the polycrystalline nature of the synthesized nanorods.

  11. Low-temperature photoluminescence analysis of CdTeSe crystals for radiation-detector applications

    SciTech Connect (OSTI)

    YANG G.; Roy, U. N.; Bolotnikov, A. E.; Cui, Y.; Camarda, G.S.; Hossain, A.; and James, R. B.

    2015-10-05

    Goal: Understanding the changes of material defects in CdTeSe following annealing. Experimental results and discussions: Infrared (IR) transmission microscopy; current-voltage measurements (Highlight: Improvement of resistivity of un-doped crystals after annealing); low-temperature photoluminescence (PL) spectrum of as-grown and annealed samples.

  12. Investigation of deep level defects in CdTe thin films

    SciTech Connect (OSTI)

    Shankar, H.; Castaldini, A.; Dauksta, E.; Medvid, A.; Cavallini, A.

    2014-02-21

    In the past few years, a large body of work has been dedicated to CdTe thin film semiconductors, as the electronic and optical properties of CdTe nanostructures make them desirable for photovoltaic applications. The performance of semiconductor devices is greatly influenced by the deep levels. Knowledge of parameters of deep levels present in as-grown materials and the identification of their origin is the key factor in the development of photovoltaic device performance. Photo Induced Current Transient Spectroscopy technique (PICTS) has proven to be a very powerful method for the study of deep levels enabling us to identify the type of traps, their activation energy and apparent capture cross section. In the present work, we report the effect of growth parameters and LASER irradiation intensity on the photo-electric and transport properties of CdTe thin films prepared by Close-Space Sublimation method using SiC electrical heating element. CdTe thin films were grown at three different source temperatures (630, 650 and 700 C). The grown films were irradiated with Nd:YAG LASER and characterized by Photo-Induced Current Transient Spectroscopy, Photocurrent measurementand Current Voltage measurements. The defect levels are found to be significantly influenced by the growth temperature.

  13. Synthesis and characterization of Cr-doped ZnO nanorod-array photocatalysts with improved activity

    SciTech Connect (OSTI)

    Chang, Chi-Jung Yang, Tsung-Lin; Weng, Yu-Ching

    2014-06-01

    Immobilized photocatalysts with high catalytic activity under UV light were prepared by growing Cr-doped ZnO nanorods on glass substrates by a hydrothermal method. The effects of Cr dopant on the surface texture, crystallinity, surface chemistry, and photoinduced charge separation and their relation with the photocatalytic degradation of Cr-doped ZnO were investigated by scanning electron microscopy, diffuse reflectance spectra, photoelectrochemical scanning electrochemical microscopy, and X-ray photoemission spectroscopy. Adding the appropriate amount of Cr dopant is a powerful way to enhance the separation of charge carriers in ZnO photocatalyst. The photocatalytic activity was improved due to the increase in surface oxygen vacancies, the separation of charge carriers, modification of the band gap, and the large surface area of the doped ZnO nanorod photocatalyst. - Graphical abstract: Photoinduced charge separation and its relation with the photocatalytic degradation activity of Cr-doped ZnO were investigated by photoelectrochemical scanning electrochemical microscopy. - Highlights: Cr dopant enhances separation of charge carries in ZnO nanorod photocatalyst. Photoinduced charge carries separation monitored by PEC-SECM. The higher the photocurrent is, the higher the photocatalytic activity is. Degradation of DB86 dye solutions under visible light finished within 50 min. Higher activity due to more oxygen vacancy, tuned band gap and more surface area.

  14. Photocatalytic reduction of aqueous mercury(II) using multi-walled carbon nanotubes/Pd-ZnO nanocomposite

    SciTech Connect (OSTI)

    Mohamed, R.M.; Abdel Salam, Mohamed

    2014-02-01

    Highlights: MWCNT/Pd-ZnO were used for photocatalytic reduction of Hg{sup 2+}. Photocatalytic reduction of Hg{sup 2+} was dependent on wt% of MWCNT, reaction time, and weight of catalyst. Catalyst re-use revealed the present photocatalyst remain effective and active after five, cycles. - Abstract: Pd-ZnO nanocatalyst supported on multi-walled carbon nanotubes was successfully synthesized via a modified solgel method, and the prepared photocatalyst was used for the environmental remediation of aqueous Hg(II) via photocatalytic reduction under visible light. The prepared MWCNTs/Pd/ZnO nanocomposite photocatalyst was characterized using X-ray diffraction, BrunauerEmmettTeller (BET), transmission electron microscopy, and UVvis spectra (UVvis). The results showed that both Pd and ZnO nanoparticles were well dispersed over the MWCNTs, and a uniform nanocomposite was formed. The results also illustrated that Pd doping can eliminate the recombination of electron-hole pairs in the catalyst, and the presence of MWCNTs in ZnO composite can change surface properties to achieve sensitivity to visible light. The results demonstrated that optimum mass ratio of CNT:ZnO:Pd were 0.04:1.0:0.08, which resulted in the exceptional performance of the photocatalyst to reduce about 100% of Hg(II) in a 100 mg L solution within 30 min.

  15. Anisotropic hot deformed magnets prepared from Zn-coated MRE-Fe-B ribbon powder (MRE?=?Nd?+?Y?+?Dy)

    SciTech Connect (OSTI)

    Tang, W; Zhou, L; Sun, K W; Dennis, K W; Kramer, M J; Anderson, I E; McCallum, R W

    2014-05-07

    Milled melt-spun ribbon flake of MRE-Fe-B coated with Zn coating using a vapor transport technique was found to have significant increase in coercivity without degrading the magnetization when the Zn thickness and heat treatment were optimized. Magnetic measurements show that 0.51?wt.?% Zn coating increases the coercivity about 1?kOe over the initial ribbon powder. After vacuum hot deformation (VHD), the VHD magnet with Zn coating of 0.5?wt.?% results in a nearly 3?kOe higher coercivity than an un-coated alloy magnet. An optimized VHD magnet with 0.5?wt.?% Zn coating obtains a coercivity of 11.2?kOe and (BH)max of 23.0 MGOe, respectively. SEM and TEM microstructures analysis demonstrates that the Zn coating on the surface of ribbon powder has diffused along the intergranular boundaries after the ribbon powder was annealed at 750?C for 30?min or was hot deformed at 700750?C.

  16. Effect of surface adsorption and non-stoichiometry on the workfunction of ZnO surfaces: A first principles study

    SciTech Connect (OSTI)

    Sun, Wei; Li, Yun; Jha, Jitendra Kumar; Shepherd, Nigel D.; Du, Jincheng

    2015-04-28

    ZnO has been actively studied for potential usage as a transparent conducting oxide (TCO) for a variety of applications including organic light emitting diodes and solar cells. In these applications, fine-tuning the workfunction of ZnO is critical for controlling interfacial barriers and improving the charge injection (or outcoupling) efficiencies. We have performed plane wave periodic density functional theory calculations to investigate the effect of different surface absorbents and surface defects (including surface non-stoichiometry) on the workfunction of ZnO. The aim was to understand the underlying mechanism of workfunction changes, in order to engineer specific workfunction modifications. Accurate calculations of workfunctions of polar surfaces were achieved by introducing balancing pseudo charges on one side of the surface to remove the dipolar effect. It was found that increasing the surface coverage of hydrocarbons (-CH{sub 3}) decreased the workfunction, while adsorption of highly electronegative-F and -CF{sub 3} groups and increases in surface O/Zn ratio increased the workfunction of ZnO. The increase of workfunction was found to be directly correlated to the enhancement variation of surface dipole moment due to adsorptions or other surface modifications. Introducing surface absorbents that increase surface dipole moment can be an effective way to increase workfunction in ZnO TCOs.

  17. Nature of red luminescence band in research-grade ZnO single crystals: A self-activated configurational transition

    SciTech Connect (OSTI)

    Chen, Y. N.; Xu, S. J. Zheng, C. C.; Ning, J. Q.; Ling, F. C. C.; Anwand, W.; Brauer, G.; Skorupa, W.

    2014-07-28

    By implanting Zn{sup +} ions into research-grade intentionally undoped ZnO single crystal for facilitating Zn interstitials (Zn{sub i}) and O vacancies (V{sub O}) which is revealed by precise X-Ray diffraction rocking curves, we observe an apparent broad red luminescence band with a nearly perfect Gaussian lineshape. This red luminescence band has the zero phonon line at ?2.4 eV and shows distinctive lattice temperature dependence which is well interpreted with the configurational coordinate model. It also shows a low kick out thermal energy and small thermal quenching energy. A self-activated optical transition between a shallow donor and the defect center of Zn{sub i}-V{sub O} complex or V{sub Zn}V{sub O} di-vacancies is proposed to be responsible for the red luminescence band. Accompanied with the optical transition, large lattice relaxation simultaneously occurs around the center, as indicated by the generation of multiphonons.

  18. Photovoltaic effect in an indium-tin-oxide/ZnO/BiFeO{sub 3}/Pt heterostructure

    SciTech Connect (OSTI)

    Fan, Zhen; Yao, Kui E-mail: msewangj@nus.edu.sg; Wang, John E-mail: msewangj@nus.edu.sg

    2014-10-20

    We have studied the photovoltaic effect in a metal/semiconductor/ferroelectric/metal heterostructure of In{sub 2}O{sub 3}-SnO{sub 2}/ZnO/BiFeO{sub 3}/Pt (ITO/ZnO/BFO/Pt) multilayer thin films. The heterolayered structure shows a short-circuit current density (J{sub sc}) of 340??A/cm{sup 2} and an energy conversion efficiency of up to 0.33% under blue monochromatic illumination. The photovoltaic mechanism, specifically in terms of the major generation site of photo-excited electron-hole (e-h) pairs and the driving forces for the separation of e-h pairs, is clarified. The significant increase in photocurrent of the ITO/ZnO/BFO/Pt compared to that of ITO/BFO/Pt is attributed to the abundant e-h pairs generated from ZnO. Ultraviolet photoelectron spectroscopy reveals the energy band alignment of ITO/ZnO/BFO/Pt, where a Schottky barrier and an n{sup +}-n junction are formed at the BFO/Pt and ZnO/BFO interfaces, respectively. Therefore, two built-in fields developed at the two interfaces are constructively responsible for the separation and transport of photo-excited e-h pairs.

  19. Changes induced in a ZnS:Cr-based electroluminescent waveguide structure by intrinsic near-infrared laser radiation

    SciTech Connect (OSTI)

    Vlasenko, N. A. Oleksenko, P. F.; Mukhlyo, M. A.; Veligura, L. I.

    2013-08-15

    The causes of changes that occur in a thin-film electroluminescent metal-insulator-semiconductor-insulator-metal waveguide structure based on ZnS:Cr (Cr concentration of {approx}4 Multiplication-Sign 10{sup 20} cm{sup -3}) upon lasing ({lambda} Almost-Equal-To 2.6 {mu}m) and that induce lasing cessation are studied. It is established that lasing ceases because of light-scattering inhomogeneities formed in the structure and, hence, optical losses enhance. The origin of the inhomogeneities and the causes of their formation are clarified by studying the surface topology and the crystal structure of constituent layers of the samples before and after lasing. The studies are performed by means of atomic force microscopy and X-ray radiography. It is shown that a substantial increase in the sizes of grains on the surface of the structure is the manifestation of changes induced in the ZnS:Cr film by recrystallization. Recrystallization is initiated by local heating by absorbed laser radiation in existing Cr clusters and quickened by a strong electric field (>1 MV cm{sup -1}). The changes observed in the ZnS:Cr film are as follows: the textured growth of ZnS crystallites, an increase in the content of Cr clusters, and the appearance of some CrS and a rather high ZnO content. Some ways for improving the stability of lasing in the ZnS:Cr-based waveguide structures are proposed.

  20. Crystal structure and physical properties of quaternary clathrates Ba{sub 8}Zn{sub x}Ge{sub 46-x-y}Si{sub y}, Ba{sub 8}(Zn,Cu){sub x}Ge{sub 46-x} and Ba{sub 8}(Zn,Pd){sub x}Ge{sub 46-x}

    SciTech Connect (OSTI)

    Nasir, Navida; Grytsiv, Andriy; Melnychenko-Koblyuk, Nataliya; Rogl, Peter; Bednar, Ingeborg; Bauer, Ernst

    2010-10-15

    Three series of vacancy-free quaternary clathrates of type I, Ba{sub 8}Zn{sub x}Ge{sub 46-x-y}Si{sub y}, Ba{sub 8}(Zn,Cu){sub x}Ge{sub 46-x}, and Ba{sub 8}(Zn,Pd){sub x}Ge{sub 46-x}, have been prepared by reactions of elemental ingots in vacuum sealed quartz at 800 {sup o}C. In all cases cubic primitive symmetry (space group Pm3n, a{approx}1.1 nm) was confirmed for the clathrate phase by X-ray powder diffraction and X-ray single crystal analyses. The lattice parameters show a linear increase with increase in Ge for Ba{sub 8}Zn{sub x}Ge{sub 46-x-y}Si{sub y}. M atoms (Zn, Pd, Cu) preferably occupy the 6d site in random mixtures. No defects were observed for the 6d site. Site preference of Ge and Si in Ba{sub 8}Zn{sub x}Ge{sub 46-x-y}Si{sub y} has been elucidated from X-ray refinement: Ge atoms linearly substitute Si in the 24k site whilst a significant deviation from linearity is observed for occupation of the 16i site. A connectivity scheme for the phase equilibria in the 'Ba{sub 8}Ge{sub 46}' corner at 800 {sup o}C has been derived and a three-dimensional isothermal section at 800 {sup o}C is presented for the Ba-Pd-Zn-Ge system. Studies of transport properties carried out for Ba{sub 8{l_brace}}Cu,Pd,Zn{r_brace}{sub x}Ge{sub 46-x} and Ba{sub 8}Zn{sub x}Si{sub y}Ge{sub 46-x-y} evidenced predominantly electrons as charge carriers and the closeness of the systems to a metal-to-insulator transition, fine-tuned by substitution and mechanical processing of starting material Ba{sub 8}Ge{sub 43}. A promising figure of merit, ZT {approx}0.45 at 750 K, has been derived for Ba{sub 8}Zn{sub 7.4}Ge{sub 19.8}Si{sub 18.8}, where pricey germanium is exchanged by reasonably cheap silicon. - Graphical abstract: Quaternary phase diagram of Ba-Pd-Zn-Ge system at 800 {sup o}C.