National Library of Energy BETA

Sample records for reynard hor se

  1. Roadmap: Horticulture Bachelor of Applied Horticulture [AS-BAH-HOR

    E-Print Network [OSTI]

    Sheridan, Scott

    Roadmap: Horticulture ­ Bachelor of Applied Horticulture [AS-BAH-HOR] College of Arts and Sciences This roadmap is a recommended semester-by-semester plan of study for this major. However, courses is taken twice, in summer 1 and 2 #12;Roadmap: Horticulture ­ Bachelor of Applied Horticulture [AS

  2. De de se

    E-Print Network [OSTI]

    Anand, Pranav

    2006-01-01

    In this dissertation, I argue against a unitary treatment of individual de se ascription. Based on consideration of Yoruba logophors and English dream-report pronouns, I show that one mechanism is best analyzed as binding ...

  3. Audit unto others hor ellipsis

    SciTech Connect (OSTI)

    Maday, J.H. Jr.

    1992-05-01

    My first encounter with a quality assurance auditor is reminiscent of an old Dodge commercial. You remember The old sheriff, masked in mirrored sunglasses, paunch hanging over his gun belt, prophesying, You're in a heap o' trouble boy '' Well, my auditor could have been kin to the sheriff; they had the same posture, attitude, and mirrored sunglasses. Plus, my auditor wore a black leather vest and sported a Buffalo Bill'' goatee. While certainly memorable, both gentlemen were far from pleasant. I'm fairly certain that the compliance auditor of old deserved this perceived association with his law enforcement counterpart. Both believed in enforcing the letter of the law, or their interpretations of it. Neither seemed capable of exercising interpretive powers, but instead relied on winning through intimidation, possibly with an eye toward claiming some version of a monthly Quota Award. Is the auditor of today any better perceived Because this first encounter of the worst kind'' made a lasting impression on me, I have dedicated considerable time and effort trying to avoid being perceived as another sheriff when I conduct audits. In my auditing career, I am determined to capitalize on each opportunity to turn negative situations, as experienced by the auditee, into meaningful opportunities for improved performance. I want to treat the auditee the way I want to be treated when I am being audited. (author)

  4. PHaSe-EFRC

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTechtail.Theory of rare Kaonforsupernovae model (JournalHearingsHuman CapitalOmega LaserPHaSe

  5. Solon SE | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page| Open Energy Information Serbia-Enhancing Capacity forSiliciumEnergy Inc Jump to:Solergy PowerSolisSolmicSolomonSE

  6. Wedding Reception Menu Hors d' Oeuvres Buffet

    E-Print Network [OSTI]

    Collett Jr., Jeffrey L.

    vegetable platters with dips Coffee, decaf coffee, hot tea, iced tea, and ice water Select six items from include mixed field green platters with a choice of dressings, starch, seasonal vegetable, rolls, butter, coffee, decaf coffee, hot tea, iced tea, and ice water. Winter Park Mediterranean Herbed Chicken Sautéed

  7. Audit unto others{hor_ellipsis}

    SciTech Connect (OSTI)

    Maday, J.H. Jr.

    1992-05-01

    My first encounter with a quality assurance auditor is reminiscent of an old Dodge commercial. You remember? The old sheriff, masked in mirrored sunglasses, paunch hanging over his gun belt, prophesying, ``You`re in a heap o` trouble boy!`` Well, my auditor could have been kin to the sheriff; they had the same posture, attitude, and mirrored sunglasses. Plus, my auditor wore a black leather vest and sported a ``Buffalo Bill`` goatee. While certainly memorable, both gentlemen were far from pleasant. I`m fairly certain that the compliance auditor of old deserved this perceived association with his law enforcement counterpart. Both believed in enforcing the letter of the law, or their interpretations of it. Neither seemed capable of exercising interpretive powers, but instead relied on winning through intimidation, possibly with an eye toward claiming some version of a monthly Quota Award. Is the auditor of today any better perceived? Because this ``first encounter of the worst kind`` made a lasting impression on me, I have dedicated considerable time and effort trying to avoid being perceived as another sheriff when I conduct audits. In my auditing career, I am determined to capitalize on each opportunity to turn negative situations, as experienced by the auditee, into meaningful opportunities for improved performance. I want to treat the auditee the way I want to be treated when I am being audited. (author)

  8. Galp associa se melhor escola de petrleo

    E-Print Network [OSTI]

    Instituto de Sistemas e Robotica

    juntaram-se à Galp para criar o ISPG, que se associou à Heriot Watt University para criar um mestrado em de uma parceria entre o ISPG e a Heriot Watt University, considera- da a melhor instituição de qualificado e de I&D deste sector para as operações que desenvolve em muitos países lusófo- nos, como Brasil

  9. University Ave SE University Ave W

    E-Print Network [OSTI]

    Thomas, David D.

    University Ave SE University Ave W Service Layer Credits: Sources: Esri, DeLorme, NAVTEQ, USGS, Intermap, i UV55 ")280 University Ave. Ramp Major Access Routes University Ave. Ramp §¨¦35W §¨¦94 ")280 Date: 5/30/2014 #12;, , , , , , , ""A TCF Bank Stadium Access Routes University Ave. Ramp University Ave SE Service

  10. REPRESENTATIVE COURSE SEQUENCE SOFTWARE ENGINEERING (SE)

    E-Print Network [OSTI]

    Huang, Haiying

    REPRESENTATIVE COURSE SEQUENCE SOFTWARE ENGINEERING (SE) Freshman Year First Semester Second Semester Second Semester CSE 3310 ­ Fundamentals of Software CSE 3302 ­ Programming Languages Engineering CSE 3320 ­ Operating Systems CSE 3315 ­ Theoretical Concepts in CSE CSE 4310 ­ Software Engineering

  11. Enriched $^{82}$Se for the LUCIFER experiment

    E-Print Network [OSTI]

    J. W. Beeman; F. Bellini; P. Benetti; L. Cardani; N. Casali; D. Chiesa; M. Clemenza; I. Dafinei; S. Di Domizio; F. Ferroni; L. Gironi; A. Giuliani; C. Gotti; M. Laubenstein; M. Maino; S. Nagorny; S. Nisi; C. Nones; F. Orio; L. Pagnanini; L. Pattavina; G. Pessina; G. Piperno; S. Pirro; E. Previtali; C. Rusconi; K. Schäffner; C. Tomei; M. Vignati

    2015-08-07

    The LUCIFER project aims at deploying the first array of enriched scintillating bolometers for the investigation of neutrinoless double-beta decay of $^{82}$Se. The matrix which embeds the source is an array of ZnSe crystals, where enriched $^{82}$Se is used as decay isotope. The radiopurity of the initial components employed for manufacturing crystals, that can be operated as bolometers, is crucial for achieving a null background level in the region of interest for double-beta decay investigations. In this work, we evaluated the radioactive content in 2.5 kg of 96.3% enriched $^{82}$Se metal, measured with a high-purity germanium detector at the Gran Sasso deep underground laboratory. The limits on internal contaminations of primordial decay chain elements of $^{232}$Th, $^{238}$U and $^{235}$U are respectively: $<$61 $\\mu$Bq/kg, $<$110 $\\mu$Bq/kg and $<$74 $\\mu$Bq/kg at 90% C.L.. The extremely low-background conditions in which the measurement was carried out and the high radiopurity of the $^{82}$Se allowed us to establish the most stringent lower limits on the half-lives of the double-beta decay of $^{82}$Se to 0$^+_1$, 2$^+_2$ and 2$^+_1$ excited states of $^{82}$Kr of 3.4$\\cdot$10$^{22}$ y, 1.3$\\cdot$10$^{22}$ y and 1.0$\\cdot$10$^{22}$ y, respectively, with a 90% C.L..

  12. ARCHITECTURE OVERVIEW TIPSTER SE/CM

    E-Print Network [OSTI]

    ARCHITECTURE OVERVIEW TIPSTER SE/CM tipster@fipster.org THE TIPSTER ARCHITECTURE The TIPSTER Architecture is a software architecture for providing Document Detection (i.e. Document Retrieval and Message Routing) and Information Extraction functions to text handling applications. The high level architecture

  13. Enriched $^{82}$Se for the LUCIFER experiment

    E-Print Network [OSTI]

    Beeman, J W; Benetti, P; Cardani, L; Casali, N; Chiesa, D; Clemenza, M; Dafinei, I; Di Domizio, S; Ferroni, F; Gironi, L; Giuliani, A; Gotti, C; Laubenstein, M; Maino, M; Nagorny, S; Nisi, S; Nones, C; Orio, F; Pagnanini, L; Pattavina, L; Pessina, G; Piperno, G; Pirro, S; Previtali, E; Rusconi, C; Schäffner, K; Tomei, C; Vignati, M

    2015-01-01

    The LUCIFER project aims at deploying the first array of enriched scintillating bolometers for the investigation of neutrinoless double-beta decay of $^{82}$Se. The matrix which embeds the source is an array of ZnSe crystals, where enriched $^{82}$Se is used as decay isotope. The radiopurity of the initial components employed for manufacturing crystals, that can be operated as bolometers, is crucial for achieving a null background level in the region of interest for double-beta decay investigations. In this work, we evaluated the radioactive content in 2.5 kg of 96.3% enriched $^{82}$Se metal, measured with a high-purity germanium detector at the Gran Sasso deep underground laboratory. The limits on internal contaminations of primordial decay chain elements of $^{232}$Th, $^{238}$U and $^{235}$U are respectively: $<$61 $\\mu$Bq/kg, $<$110 $\\mu$Bq/kg and $<$74 $\\mu$Bq/kg at 90% C.L.. The extremely low-background conditions in which the measurement was carried out and the high radiopurity of the $^{82}$...

  14. NPS-SE-10-003 POSTGRADUATE

    E-Print Network [OSTI]

    NPS-SE-10-003 NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA INTEGRATED PROJECT An Integrated Command and Control Architecture Concept for Unmanned Systems in the Year of 2030 By Omari D Buckley reporting burden for this collection of information is estimated to average 1 hour per response, including

  15. Q Cells SE | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIX ECoop Inc Jump to:Newberg,Energy LLCALLETE Inc dEAPrysmianPvT Capital GmbhQ Cells SE

  16. Scientific Achievement Networks of highly photoresponsive crystalline GaSe

    E-Print Network [OSTI]

    Geohegan, David B.

    Scientific Achievement Networks of highly photoresponsive crystalline GaSe nanosheets a crystalline GaSe target was adjusted to directly grow networks of interconnected triangular GaSe crystalline nanosheets of ~ 200 nm size (inset shows atomic

  17. Reaction kinetics of a-CuInSe2 formation from an In2Se3/CuSe bilayer precursor film

    E-Print Network [OSTI]

    Anderson, Timothy J.

    with Ga or S are proven absorber materials for high efficiency thin film solar cells. Interestingly CIGS system using the stacked elemental film precursors (e.g. glass/Cu/In/Se, glass/Cu/Se, glass

  18. SE-72/AS-72 generator system based on Se extraction/ As reextraction

    DOE Patents [OSTI]

    Fassbender, Michael Ernst; Ballard, Beau D

    2013-09-10

    The preparation of a .sup.72Se/.sup.72As radioisotope generator involves forming an acidic aqueous solution of an irradiated alkali bromide target such as a NaBr target, oxidizing soluble bromide in the solution to elemental bromine, removing the elemental bromine, evaporating the resulting solution to a residue, removing hydrogen chloride from the residue, forming an acidic aqueous solution of the residue, adding a chelator that selectively forms a chelation complex with selenium, and extracting the chelation complex from the acidic aqueous solution into an organic phase. As the .sup.72Se generates .sup.72As in the organic phase, the .sup.72As may be extracted repeatedly from the organic phase with an aqueous acid solution.

  19. 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.

  20. 31P Solid State NMR Studies of Metal Selenophosphates Containing [P2Se6]4-, [P4Se10]4-, [PSe4]3-, [P2Se7]4-, and [P2Se9]4-Ligands

    E-Print Network [OSTI]

    Weliky, David

    31P Solid State NMR Studies of Metal Selenophosphates Containing [P2Se6]4-, [P4Se10]4-, [PSe4]3-, [P2Se7]4-, and [P2Se9]4- Ligands Christian G. Canlas, Mercouri G. Kanatzidis, and David P. Weliky P solid-state nuclear magnetic resonance (NMR) spectra of 12 metal-containing selenophosphates have

  1. 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.

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

    SciTech Connect (OSTI)

    Valverde-Chávez, D. A.; Sutara, F.; Hernández-Calderón, 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.

  3. CuInSe/sub 2/-based photoelectrochemical cells: their use in characterization of thin CuInSe/sub 2/ films, and as photovoltaic cells per se

    SciTech Connect (OSTI)

    Cahen, D.; Chen, Y.W.; Ireland, P.J.; Noufi, R.; Turner, J.A.; Rincon, C.; Bachmann, K.J.

    1984-05-01

    Photoelectrochemistry has been employed to characterize the p-CuInSe/sub 2/ component of the CdS/CuInSe/sub 2/ on-metal and a nonaqueous electrolyte containing a redox couple not specifically adsorbed onto the semiconductor, we can test the films for photovoltaic activity and obtain effective electronic properties of them, before CdS deposition, in a nondestructive manner. Electrochemical decomposition of CuInSe/sub 2/ was investigated in acetonitrile solutions to determine the mechanism of decomposition (n and p) in the dark and under illumination. Electrochemical, solution chemical and surface analyses confirmed at the light-assisted decomposition of CuInSe/sub 2/ resulted in metal ions and elemental chalcogen. On the basis of the results from the electrochemical decomposition, and studies on the solid state chemistry of the (Cu/sub 2/Se)/sub x/(In/sub 2/Se/sub 3/)/sub 1-x/ system and surface analyses, the CuInSe/sub 2//polyiodide interface was stabilized and up to 11.7% conversion efficiencies were obtained.

  4. Thermoelectric transport of Se-rich Ag{sub 2}Se in normal phases and phase transitions

    SciTech Connect (OSTI)

    Mi, Wenlong; Lv, Yanhong; Qiu, Pengfei; Shi, Xun E-mail: cld@mail.sic.ac.cn; Chen, Lidong E-mail: cld@mail.sic.ac.cn; Zhang, Tiansong

    2014-03-31

    Small amount of Se atoms are used to tune the carrier concentrations (n{sub H}) and electrical transport in Ag{sub 2}Se. Significant enhancements in power factor and thermoelectric figure of merit (zT) are observed in the compositions of Ag{sub 2}Se{sub 1.06} and Ag{sub 2}Se{sub 1.08}. The excessive Se atoms do not change the intrinsically electron-conducting character in Ag{sub 2}Se. The detailed analysis reveals the experiment optimum carrier concentration in Ag{sub 2}Se is around 5?×?10{sup 18}?cm{sup ?3}. We also investigate the temperature of maximum zT and the thermoelectric transport during the first order phase transitions using the recently developed measurement system.

  5. Glass formation and the third harmonic generation of Cu{sub 2}Se–GeSe{sub 2}–As{sub 2}Se{sub 3} glasses

    SciTech Connect (OSTI)

    Reshak, A. H.; Klymovych, O. S.; Zmiy, O. F.; Myronchuk, G. L.; Zamuruyeva, O. V.; Alahmed, Z. A.; Chyský, J.; Bila, Jiri; Kamarudin, H.

    2014-10-14

    We have performed the investigation of the nonlinear optical properties namely the third harmonic generation (THG) of the glass-formation region in the Cu{sub 2}Se–GeSe{sub 2}–As{sub 2}Se{sub 3} system. The samples were synthesized by direct single-temperature method from high-purity elementary substances. We have found that the value of disorder parameter ? depends on the composition of the glassy alloys. The measurements show that increasing the Cu{sub 2}Se concentration leads to increased slope of the absorption edge, which may be explained by the decrease of the height of random potential relief for the electrons in the tails of the state density which border the band edges. A very sharp increase in the THG at low temperature was observed. Significant enhancement in THG was obtained with decreasing the energy gap, which agreed well with the nonlinear optical susceptibilities obtained from other glasses.

  6. www.medicine.gu.se Minnesanteckningar forskarutbildningsutskottet, inst. fr medicin

    E-Print Network [OSTI]

    www.medicine.gu.se Minnesanteckningar forskarutbildningsutskottet, inst. för medicin 2015 inflammationsforskning hälsas välkommen som ny ledamot i FUU. Per Ladenvall vid avd. för molekylär och klinisk medicin

  7. 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.

  8. ME/SE 740 Vision, Robotics & Planning Spring 2009

    E-Print Network [OSTI]

    Lin, Xi

    ME/SE 740 ­ Vision, Robotics & Planning Spring 2009 Professor Pierre Dupont, Room 408, 110 Cummington Street 353-9596 pierre@bu.edu Required Text: A Mathematical Introduction to ROBOTIC MANIPULATION://www.engin.umich.edu/group/ctm/basic/basic.html #12;ME/SE 740 ­ Vision, Robotics & Planning 1/22/20092 Course Topics: 1. Introduction: · Historical

  9. APS/DPP 111207-se 1 University Fusion Association Meeting

    E-Print Network [OSTI]

    Eckstrand for Office of Fusion Energy Sciences Fusion Energy Sciences Program Update www.ofes.fusion.doe.gov U.S. Department of Energy's Office of Science #12;APS/DPP 111207-se 2 Topics · Budget status/DPP 111207-se 3 FY 2008 Fusion Energy Sciences Congressional Budget Request 144.6 146.3 20.8 311.7 FY 2007

  10. Approved Module Information for SE4031, 2014/5 Module Title/Name: Extended Integrative Option Module Code: SE4031

    E-Print Network [OSTI]

    Neirotti, Juan Pablo

    Approved Module Information for SE4031, 2014/5 Module Title/Name: Extended Integrative Option Module Code: SE4031 School: Engineering and Applied Science Module Type: Standard Module New Module? No Module Credits: 30 Module Management Information Module Leader Name Trevor Oliver Email Address t

  11. Optical Probing of metamagnetic phases in epitaxial EuSe

    SciTech Connect (OSTI)

    Galgano, G. D.; Henriques, A. B.; Bauer, G.; Springholz, G.

    2011-12-23

    EuSe is a wide gap magnetic semiconductors with a potential for applications in proof-of-concept spintronic devices. When the temperature is lowered, EuSe goes through sharp transitions between a variety of magnetic phases and is thus described as metamagnetic. The purpose of the present investigation is to correlate the magnetic order to the sharp dichroic doublet, discovered recently in high quality thin epitaxial layers of EuSe, grown by molecular beam epitaxy. We report detailed measurements of the doublet positions and intensities as a function of magnetic field in low temperatures, covering several magnetic phases.

  12. Enhanced thermoelectric power and electronic correlations in RuSe?

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

    Wang, Kefeng; Wang, Aifeng; Tomic, A.; Wang, Limin; Abeykoon, A. M. Milinda; Dooryhee, E.; Billinge, S. J.L.; Petrovic, C.

    2015-03-03

    We report the electronic structure, electric and thermal transport properties of Ru??xIrxSe? (x ? 0.2). RuSe? is a semiconductor that crystallizes in a cubic pyrite unit cell. The Seebeck coefficient of RuSe? exceeds -200 µV/K around 730 K. Ir substitution results in the suppression of the resistivity and the Seebeck coefficient, suggesting the removal of the peaks in density of states near the Fermi level. Ru?.?Ir?.?Se? shows a semiconductor-metal crossover at about 30 K. The magnetic field restores the semiconducting behavior. Our results indicate the importance of the electronic correlations in enhanced thermoelectricity of RuSb?.

  13. Hot exciton transport in ZnSe quantum wells

    E-Print Network [OSTI]

    Zhao, Hui; Moehl, Sebastian; Wachter, Sven; Kalt, Heinz

    2002-02-01

    The in-plane transport of excitons in ZnSe quantum wells is investigated directly by microphotoluminescence in combination with a solid immersion lens. Due to the strong Froehlich coupling, the initial kinetic energy of the excitons is well...

  14. 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.

  15. Magneto-optical characterizations of FeTe???Se??? thin...

    Office of Scientific and Technical Information (OSTI)

    in the two thin films. Compared with bulk crystals, FeTeSe thin film demonstrates not only higher Tc, but also much larger Jc, which is attractive for...

  16. Computando lo aspero Por que se cuelgan las computadoras?

    E-Print Network [OSTI]

    Figueira, Santiago

    ejemplo 0 + 1 = 1. Tambi´en puedo al 1 sumarle 1 y obtener el 2: (0 + 1) + 1 = 2 recursi´on: una funci´on que se llama a s´i misma. Por ejemplo, a la funci´on suma se puede definir como: suma(m, n) = n si m´olo un peque~no n´umero de s´imbolos reciben atenci´on (en el ejemplo, 2). Hay una cantidad finita de s

  17. Synthesis and properties of new CdSe-AgI-As{sub 2}Se{sub 3} chalcogenide glasses

    SciTech Connect (OSTI)

    Kassem, M.; ULCO, LPCA, EAC CNRS 4493 F-59140 Dunkerque ; Le Coq, D.; Fourmentin, M.; Hindle, F.; Bokova, M.; Cuisset, A.; Masselin, P.; Bychkov, E.; ULCO, LPCA, EAC CNRS 4493 F-59140 Dunkerque

    2011-02-15

    Research highlights: {yields} Determination of the glass-forming region in the pseudo-ternary CdSe-AgI-As{sub 2}Se{sub 3} system. {yields} Characterization of macroscopic properties of the new CdSe-AgI-As{sub 2}Se{sub 3} glasses. {yields} Far infrared transmission of chalcogenide glasses. {yields} Characterization of the total conductivity of CdSe-AgI-As{sub 2}Se{sub 3} glasses. -- Abstract: The glass-forming region in the pseudo-ternary CdSe-AgI-As{sub 2}Se{sub 3} system was determined. Measurements including differential scanning calorimetry (DSC), density, and X-ray diffraction were performed. The effect resulting from the addition of CdSe or AgI has been highlighted by examining three series of different base glasses. The characteristic temperatures of the glass samples, including glass transition (T{sub g}), crystallisation (T{sub x}), and melting (T{sub m}) temperatures are reported and used to calculate their {Delta}T = T{sub x} - T{sub g} and their Hruby, H{sub r} = (T{sub x} - T{sub g})/(T{sub m} - T{sub x}), criteria. Evolution of the total electrical conductivity {sigma} and the room temperature conductivity {sigma}{sub 298} was also studied. The terahertz transparency domain in the 50-600 cm{sup -1} region was pointed for different chalcogenide glasses (ChGs) and the potential of the THz spectroscopy was suggested to obtain structural information on ChGs.

  18. Giant Piezoelectricity in Monolayer Group IV Monochalcogenides: SnSe, SnS, GeSe and GeS

    E-Print Network [OSTI]

    Fei, Ruixiang; Li, Ju; Yang, Li

    2015-01-01

    We predict enormous piezoelectric effects in intrinsic monolayer group IV monochalcogenides (MX, M=Sn or Ge, X=Se or S), including SnSe, SnS, GeSe and GeS. Using first-principle simulations based on the modern theory of polarization, we find that their characteristic piezoelectric coefficients are about two orders of magnitude larger than those of other 2D materials, such as MoS2 and GaSe, and bulk quartz and AlN which are widely used in industry. This enhancement is a result of the unique "puckered" D2h symmetry and weaker chemical bonds of monolayer group IV monochalcogenides. Given the achieved experimental advances in fabrication of monolayers, their flexible character and ability to withstand enormous strain, these 2D structures with giant piezoelectric effects may be promising for a broad range of applications, such as nano-sized sensors, piezotronics, and energy harvesting in portable electronic devices.

  19. Excited-State Relaxation in PbSe Quantum Dots

    SciTech Connect (OSTI)

    An, J. M.; Califano, M.; Franceschetti, A.; Zunger, A.

    2008-01-01

    In solids the phonon-assisted, nonradiative decay from high-energy electronic excited states to low-energy electronic excited states is picosecond fast. It was hoped that electron and hole relaxation could be slowed down in quantum dots, due to the unavailability of phonons energy matched to the large energy-level spacings ('phonon-bottleneck'). However, excited-state relaxation was observed to be rather fast ({le}1 ps) in InP, CdSe, and ZnO dots, and explained by an efficient Auger mechanism, whereby the excess energy of electrons is nonradiatively transferred to holes, which can then rapidly decay by phonon emission, by virtue of the densely spaced valence-band levels. The recent emergence of PbSe as a novel quantum-dot material has rekindled the hope for a slow down of excited-state relaxation because hole relaxation was deemed to be ineffective on account of the widely spaced hole levels. The assumption of sparse hole energy levels in PbSe was based on an effective-mass argument based on the light effective mass of the hole. Surprisingly, fast intraband relaxation times of 1-7 ps were observed in PbSe quantum dots and have been considered contradictory with the Auger cooling mechanism because of the assumed sparsity of the hole energy levels. Our pseudopotential calculations, however, do not support the scenario of sparse hole levels in PbSe: Because of the existence of three valence-band maxima in the bulk PbSe band structure, hole energy levels are densely spaced, in contradiction with simple effective-mass models. The remaining question is whether the Auger decay channel is sufficiently fast to account for the fast intraband relaxation. Using the atomistic pseudopotential wave functions of Pb{sub 2046}Se{sub 2117} and Pb{sub 260}Se{sub 249} quantum dots, we explicitly calculated the electron-hole Coulomb integrals and the P {yields} S electron Auger relaxation rate. We find that the Auger mechanism can explain the experimentally observed P {yields} S intraband decay time scale without the need to invoke any exotic relaxation mechanisms.

  20. se de doctorat en informatique Comprendre le Web cach

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    niveau à l'aide de telles descriptions. Abstract e hidden Web (also known as deep or invisible Web'informations, complexité Keywords: hidden Web, deep Web, databases, information extraction, complexity tel-00198150,versionèse de doctorat en informatique Comprendre le Web caché Understanding the Hidden Web Pierre

  1. MINIREVIEW / MINISYNTHE` SE The role of chromatin structure in regulating

    E-Print Network [OSTI]

    Krebs, Jocelyn E.

    within many stress-induced promoters, such as stress re- sponse elements and heat shock elements, allow. Key words: chromatin, transcription, stress response, heat shock. Re´sume´ : Toutes les cellules, quMINIREVIEW / MINISYNTHE` SE The role of chromatin structure in regulating stress

  2. ctualmente se afronta una im-portante prdida de biodiversi-

    E-Print Network [OSTI]

    Figuerola, Jordi

    a los medios de comunicación y sean cada vez más tratadas en la prensa científica, no son un fenómeno enfermedades con nuestras actividades por encima del nivel que se daba en siglos ante- riores. Por último y percepción pública sobre la necesidad de conservar el medio natural (¿no sería mejor ma- tar a todos los

  3. www.medicine.gu.se Minnesanteckningar Forskarutbildningsutskottet, inst. fr medicin

    E-Print Network [OSTI]

    www.medicine.gu.se Minnesanteckningar ­ Forskarutbildningsutskottet, inst. för medicin 2015, forskare vid avd. för molekylär och klinisk medicin hälsas välkommen som ny ledamot i FUU. Pauline ersätter informerade om hur antagningarna granskas vid avd. för molekylär och klinisk medicin. De vanligaste bristerna

  4. Transformation toughening in an antiferroelectric ceramic *, S.E. Younga

    E-Print Network [OSTI]

    Hong, Wei

    1 Transformation toughening in an antiferroelectric ceramic X. Tana, *, S.E. Younga , Y.H. Seob , J of the crystal symmetry, dielectric constant, field-induced polarization, and Raman spectrum on ceramic Pb0.99Nb0 is demonstrated in the antiferroelectric ceramic with both indentation fracture and R-curve experiments

  5. 2030 SE Marine Science Drive Newport, Oregon 973665-5296

    E-Print Network [OSTI]

    Wright, Dawn Jeannine

    2030 SE Marine Science Drive Newport, Oregon 973665-5296 Telephone 541-867-0100 Fax 541-867-0138 Web Page http://hmsc.oregonstate.edu Oregon State University Hatfield Marine Science Center 2006.....................................2 Coastal Oregon Marine Experiment Station...........................2 OSU-COMES Seafood Research

  6. Quantum confined acceptors and donors in InSe nanosheets

    SciTech Connect (OSTI)

    Mudd, G. W.; Patanè, A. Makarovsky, O.; Eaves, L.; Kudrynskyi, Z. R.; Kovalyuk, Z. D.; Fay, M. W.; Zólyomi, V.; Falko, V.

    2014-12-01

    We report on the radiative recombination of photo-excited carriers bound at native donors and acceptors in exfoliated nanoflakes of nominally undoped rhombohedral ?-polytype InSe. The binding energies of these states are found to increase with the decrease in flake thickness, L. We model their dependence on L using a two-dimensional hydrogenic model for impurities and show that they are strongly sensitive to the position of the impurities within the nanolayer.

  7. Does MoSE cope with inland tsunamis hazard?

    E-Print Network [OSTI]

    Panza, Giuliano Francesco; Romanelli, Fabio

    2014-01-01

    In this work we use morphostructural zonation and pattern recognition techniques to identify a potential seismic source located inland very near Venice, and then we evaluate how a tsunami wave generated from this source can affect the MoSE gates if they are standing up (closed) during the tsunami event. From our simulation we get both peaks and troughs as first arrivals: the behavior of the barriers in these two situations could be a very important design matter.

  8. Perlick: Order (2013-SE-14001) | Department of Energy

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousMathematicsEnergyInterested PartiesBuilding energy codes havePUBLICofPatriciaOrder (2013-SE-14001)

  9. Perlick: Proposed Penalty (2013-SE-14001) | Department of Energy

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousMathematicsEnergyInterested PartiesBuilding energy codes havePUBLICofPatriciaOrder (2013-SE-14001)Proposed

  10. Metal contacts on ZnSe and GaN

    SciTech Connect (OSTI)

    Duxstad, K J [Univ. of California, Berkeley, CA (United States). Materials Science and Mineral Engineering

    1997-05-01

    Recently, considerable interest has been focused on the development of blue light emitting materials and devices. The focus has been on GaN and ZnSe, direct band gap semiconductors with bands gaps of 3.4 and 2.6 eV, respectively. To have efficient, reliable devices it is necessary to have thermally and electrically stable Ohmic contacts. This requires knowledge of the metal-semiconductor reaction behavior. To date few studies have investigated this behavior. Much information has accumulated over the years on the behavior of metals on Si and GaAs. This thesis provides new knowledge for the more ionic wide band gap semiconductors. The initial reaction temperatures, first phases formed, and phase stability of Pt, Pd, and Ni on both semiconductors were investigated. The reactions of these metals on ZnSe and GaN are discussed in detail and correlated with predicted behavior. In addition, comparisons are made between these highly ionic semiconductors and Si and GaAs. The trends observed here should also be applicable to other II-VI and III-Nitride semiconductor systems, while the information on phase formation and stability should be useful in the development of contacts for ZnSe and GaN devices.

  11. APdCu(Se2)(Se3) (A ) K and Rb): New Quaternary Copper Palladium Polyselenides with Unusual Metal-Selenium Coordination

    E-Print Network [OSTI]

    Li, Jing

    APdCu(Se2)(Se3) (A ) K and Rb): New Quaternary Copper Palladium Polyselenides with Unusual Metal structurally characterized quaternary copper palladium polychalcogenides with a (Se2)2- and a (Se3)2- fragment ) K and Rb), which are the first quaternary copper palladium polychalcogenides obtained

  12. Bi-Se doped with Cu, p-type semiconductor

    DOE Patents [OSTI]

    Bhattacharya, Raghu Nath; Phok, Sovannary; Parilla, Philip Anthony

    2013-08-20

    A Bi--Se doped with Cu, p-type semiconductor, preferably used as an absorber material in a photovoltaic device. Preferably the semiconductor has at least 20 molar percent Cu. In a preferred embodiment, the semiconductor comprises at least 28 molar percent of Cu. In one embodiment, the semiconductor comprises a molar percentage of Cu and Bi whereby the molar percentage of Cu divided by the molar percentage of Bi is greater than 1.2. In a preferred embodiment, the semiconductor is manufactured as a thin film having a thickness less than 600 nm.

  13. Sunshine Lighting: Order (2014-SE-54008) | Department of Energy

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIX E LIST OF APPLICABLEStatutory Authority forPerk | DepartmentOrder (2014-SE-54008)

  14. Victory: Order (2015-SE-42033) | Department of Energy

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIX E LIST OF APPLICABLEStatutoryinEnable LowNewsEnergyOrder (2015-SE-42033) Victory:

  15. Victory: Proposed Penalty (2015-SE-42033) | Department of Energy

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIX E LIST OF APPLICABLEStatutoryinEnable LowNewsEnergyOrder (2015-SE-42033)

  16. 1.0 Espa,cos de Banach de se,c"oes de um fibrado vetorial. Definiremos nesta se,c"ao v'arios espa,cos vetoriais de se,c"oes de um fibr*

    E-Print Network [OSTI]

    Tausk, Daniel Victor

    1.0 Espa,cos de Banach de se,c"oes de um fibrado vetorial. Definiremos nesta se,c"ao v'arios espa,cos vetoriais de se,c"oes de um fibr* *ado vetorial sobre uma variedade compacta (possivelmente com bordo). Definiremos normas nestes esp* *a,cos mediante as quais eles se tornar"ao espa,cos de

  17. Geometric Tracking Control of a Quadrotor UAV on SE(3)

    E-Print Network [OSTI]

    Lee, Taeyoung; McClamroch, N Harris

    2010-01-01

    This paper provides new results for the tracking control of a quadrotor unmanned aerial vehicle (UAV). The UAV has four input degrees of freedom, namely the magnitudes of the four rotor thrusts, that are used to control the six translational and rotational degrees of freedom, and to achieve asymptotic tracking of four outputs, namely, three position variables for the vehicle center of mass and the direction of one vehicle body-fixed axis. A globally defined model of the quadrotor UAV rigid body dynamics is introduced as a basis for the analysis. A nonlinear tracking controller is developed on the special Euclidean group SE(3) and it is shown to have desirable closed loop properties that are almost global. Several numerical examples, including an example in which the quadrotor recovers from being initially upside down, illustrate the versatility of the controller.

  18. Fluorescence quenching of CdSe quantum dots on graphene

    SciTech Connect (OSTI)

    Guo, Xi Tao; Hua Ni, Zhen, E-mail: zhni@seu.edu.cn; Yan Nan, Hai; Hui Wang, Wen [Department of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189 (China)] [Department of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189 (China); Yan Liao, Chun [Physics Department, National Photoelectric Technology and Functional Materials and Application of Science and Technology International Cooperation Base, Northwest University, Xi'an 710069 (China)] [Physics Department, National Photoelectric Technology and Functional Materials and Application of Science and Technology International Cooperation Base, Northwest University, Xi'an 710069 (China); Zhang, Yan; Wei Zhao, Wei [Jiangsu Key Laboratory for Design and Fabrication of Micro-Nano Biomedical Instruments, School of Mechanical Engineering, Southeast University, Nanjing 211189 (China)] [Jiangsu Key Laboratory for Design and Fabrication of Micro-Nano Biomedical Instruments, School of Mechanical Engineering, Southeast University, Nanjing 211189 (China)

    2013-11-11

    We studied systematically the fluorescence quenching of CdSe quantum dots (QDs) on graphene and its multilayers, as well as graphene oxide (GO) and reduced graphene oxide (rGO). Raman intensity of QDs was used as a quantitatively measurement of its concentration in order to achieve a reliable quenching factor (QF). It was found that the QF of graphene (?13.1) and its multilayers is much larger than rGO (?4.4), while GO (?1.5) has the lowest quenching efficiency, which suggests that the graphitic structure is an important factor for quenching the fluorescence of QDs. It was also revealed that the QF of graphene is not strongly dependent on its thicknesses.

  19. 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)

    Hernández-Calderón, 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.

  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. Secretary Chu to Lead Delegation to SE4All, CEM Conferences in...

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

    to Lead Delegation to SE4All, CEM Conferences in London Secretary Chu to Lead Delegation to SE4All, CEM Conferences in London April 9, 2012 - 10:13am Addthis WASHINGTON, DC - Later...

  2. Sbado 10.11.2012 English | Deutsch | Franais | Italiano | Espaol | Portugus | | | Fazer login | Cadastre-se

    E-Print Network [OSTI]

    Barbosa, Marcia C. B.

    dispararam contra drone dos EUA 09 Novembro, 2012 - 16:57 O sobrinho de George W. Bush, meio hispânico, se

  3. SE2NN11 Neural Networks Part B Dr Richard Mitchell, 2014 1

    E-Print Network [OSTI]

    Mitchell, Richard

    SE2NN11 ­ Neural Networks ­ Part B © Dr Richard Mitchell, 2014 1 p1 RJM 16/09/14 SE2NN11 Neural Networks ­ Part B © Dr Richard Mitchell 2014 SE2NN11 Neural Networks : Part B In Part B of the course, I Networks Including Stochastic Diffusion Search p2 RJM 16/09/14 SE2NN11 Neural Networks ­ Part B © Dr

  4. Energy relaxation in CdSe nanocrystals: the effects of morphology and film preparation

    E-Print Network [OSTI]

    Ruan, Xiulin

    solar cells. harvesting light energy with CdSe nanocrystals molecularly linked to mesoscopic TiO2 filmsEnergy relaxation in CdSe nanocrystals: the effects of morphology and film preparation Bryan T time-resolved absorption spectroscopy is used to investigate exciton dynamics in CdSe nanocrystal films

  5. DISSERTATION ANTICIPATED PERFORMANCE OF Cu(In,Ga)Se2 SOLAR CELLS IN THE

    E-Print Network [OSTI]

    Sites, James R.

    i DISSERTATION ANTICIPATED PERFORMANCE OF Cu(In,Ga)Se2 SOLAR CELLS IN THE THIN-FILM LIMIT Submitted ENTITLED `ANTICIPATED PERFORMANCE OF Cu(In,Ga)Se2 SOLAR CELLS IN THE THIN-FILM LIMIT' BE ACCEPTED(In,Ga)Se2 SOLAR CELLS IN THE THIN-FILM LIMIT The demand for alternative sources of energy is rapidly

  6. Method of synthesizing and growing copper-indium-diselenide (CuInSe/sub 2/) crystals

    DOE Patents [OSTI]

    Ciszek, T.F.

    1984-11-29

    A process for preparing CuInSe/sub 2/ crystals includes melting a sufficient quantity of B/sub 2/O/sub 2/ along with stochiometric quantities of Cu, In, and Se in a crucible in a high-pressure atmosphere of inert gas to encapsulate the CuInSe/sub 2/ melt and confine the Se to the crucible. Additional Se in the range of 1.8 to 2.2% over the stochiometric quantity is preferred to make up for small amounts of Se lost in the process. The melt can then be cooled slowly to form the crystal as direct solidification, or the crystal can be grown by inserting a seed crystal through the B/sub 2/O/sub 3/ encapsulate into contact with the CuInSe/sub 2/ melt and withdrawing the seed upwardly to grow the crystal thereon from the melt.

  7. Observation and Measurement of Se-79 in SRS High-Level Tank Fission Product Waste

    SciTech Connect (OSTI)

    Dewberry, R.A.

    2000-08-21

    The authors report the first observation of confirmed Se-79 activity in Savannah River Site high level fission product waste. Se-79 was measured after a seven step chemical treatment to remove interfering activity from Cs-137, Sr-90, and plutonium at levels 105 times higher than the observed Se-79 content and to remove Tc-99 at levels 300 times higher than observed Se-79. Se-79 was measured by liquid scintillation beta-decay counting after specific tests to eliminate uncertainties from possible contributions from Tc-99, Pm-147, Sm-151, Zr-93, or Pu-241, whose beta-decay spectra could appear similar to that of Se-79, and whose content would be expected at levels near or greater than Se-79.

  8. SLU, Box 58, SE-230 53Alnarp, Sverige tel: +46 (0)40-4150 00 Org.nr 202100-2817 info@slu.se

    E-Print Network [OSTI]

    .slu.se 1(7) FUSE- Future Urban Sustainable Environments Caroline Dahl, projektledare STRATEGISK PLAN Strategisk plan för FUSE verksamhetsperiod 2013-2016 Projektnamn: Future Urban Sustainable Environment, FUSE

  9. ADVANCES IN SE-79 ANALYSES ON SAVANNAH RIVER SITE RADIOACTIVE WASTE MATRICES

    SciTech Connect (OSTI)

    Diprete, D; C Diprete, C; Ned Bibler, N; Cj Bannochie, C; Michael Hay, M

    2009-03-16

    Waste cleanup efforts underway at the United States Department of Energy's (DOE) Savannah River Site (SRS) in South Carolina, as well as other DOE nuclear sites, have created a need to characterize {sup 79}Se in radioactive waste inventories. Successful analysis of {sup 79}Se in high activity waste matrices is challenging for a variety of reasons. As a result of these unique challenges, the successful quantification of {sup 79}Se in the types of matrices present at SRS requires an extremely efficient and selective separation of {sup 79}Se from high levels of interfering radionuclides. A robust {sup 79}Se radiochemical separation method has been developed at the Savannah River National Laboratory (SRNL) which is routinely capable of successfully purifying {sup 79}Se from a wide range of interfering radioactive species. In addition to a dramatic improvements in the Kd, ease, and reproducibility of the analysis, the laboratory time has been reduced from several days to only 6 hours.

  10. Enhanced ripening behavior of Mg-doped CdSe quantum dots

    E-Print Network [OSTI]

    Kim, Tae-Geun

    In this study, CdO and Mg acetate were added into a mixture of paraffin oil and oleic acid (45:5) by 5 and 1 mEnhanced ripening behavior of Mg-doped CdSe quantum dots Yun-Mo Sung,a) Woo-Chul Kwak, and Woong November 2007; accepted 24 March 2008) Pure CdSe and Mg-doped CdSe nanocrystal quantum dots were

  11. Hot-pressed ceramic Cr2+ :ZnSe gain-switched

    E-Print Network [OSTI]

    Mirov, Sergey B.

    Hot-pressed ceramic Cr2+ :ZnSe gain-switched laser A. Gallian, V. V. Fedorov, and S. B. Mirov: The technology of hot-pressed Cr2+ :ZnSe ceramic preparation is reported. Comparative gain-switched lasing of hot­pressed ceramic and CVD grown Cr2+ :ZnSe samples with slope efficiencies up to 10 % and output energies up to 2 m

  12. DISSERTATION DEVICE PHYSICS OF Cu(In,Ga)Se2 THIN-FILM SOLAR CELLS

    E-Print Network [OSTI]

    Sites, James R.

    OF Cu(In,Ga)Se2 THIN-FILM SOLAR CELLS Thin-film solar cells have the potential to be an important contributor to the global energy demand by the mid-21st-century. Cu(In,Ga)Se2 (CIGS) solar cells, which haveDISSERTATION DEVICE PHYSICS OF Cu(In,Ga)Se2 THIN-FILM SOLAR CELLS Submitted by Markus Gloeckler

  13. BASIN VER DE GREAT ER ANETH BU G BAR KER DOME HOR SESH OE UTE DOME

    Gasoline and Diesel Fuel Update (EIA)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustments (Billion Cubic Feet) Wyoming Dry NaturalPrices1 Table 1.101 (Million Short6 Macroeconomic88.04WBOE

  14. BASIN VER DE GREAT ER ANETH BU G BAR KER DOME HOR SESH OE UTE DOME

    Gasoline and Diesel Fuel Update (EIA)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustments (Billion Cubic Feet) Wyoming Dry NaturalPrices1 Table 1.101 (Million Short6 Macroeconomic88.04WBOEGas

  15. BASIN VER DE GREAT ER ANETH BU G BAR KER DOME HOR SESH OE UTE DOME

    Gasoline and Diesel Fuel Update (EIA)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustments (Billion Cubic Feet) Wyoming Dry NaturalPrices1 Table 1.101 (Million Short6

  16. Mechanical and electronic-structure properties of compressed CdSe tetrapod nanocrystals

    E-Print Network [OSTI]

    Schrier, Joshua; Lee, Byounghak; Wang, Lin-Wang

    2008-01-01

    Mechanical and electronic-structure properties of compressed94720 USA The coupling of mechanical and optical propertiestheoretical examination of the mechanical properties of CdSe

  17. Photovoltaic performance of ultra-small PbSe quantum dots

    E-Print Network [OSTI]

    Ma, Wanli

    2014-01-01

    Y; Alivisatos, AP, Photovoltaic Devices Employing TernaryPhotovoltaic performance of ultra-small PbSe quantum dotsquantum dot, solar cell, photovoltaic, quantum size effect

  18. Photovoltaic Devices Employing Ternary PbSxSe1-x Nanocrystals

    E-Print Network [OSTI]

    Alivisatos, A. Paul

    2009-01-01

    Photovoltaic Devices Employing Ternary PbS x Se 1-xalloy nanoparticles. Photovoltaic devices made using ternaryInformation for Efficient Photovoltaic Devices Employing

  19. PERFORMANCE OF CdSe TETRAPODS-GOLD AS NANOSTRUCTURE ELECTROCHEMICAL MATERIALS IN PHOTOVOLTAIC CELLS

    E-Print Network [OSTI]

    Natelson, Douglas

    PERFORMANCE OF CdSe TETRAPODS-GOLD AS NANOSTRUCTURE ELECTROCHEMICAL MATERIALS IN PHOTOVOLTAIC CELLS antenna arrays are assembled by coating on CdSe tetrapod templates; the rectifying barrier is formed and reduce the costs associated with conventional solar cells, including multi-bandgap materials [5

  20. Ultrafast Spectroscopy of CdSe Nanocrystals: Morphological and Environmental Effects on Nonradiative and Nonadiabatic Relaxation

    E-Print Network [OSTI]

    Xu, Xianfan

    Ultrafast Spectroscopy of CdSe Nanocrystals: Morphological and Environmental Effects of various morpholo- gies has been demonstrated in CdSe, such as quantum dots (QDs),3 quantum rods (QRs),4 devices and technologies have come to fruition, for example, nanocrystal solar cells (NCSC),7 lasers,8

  1. Volume 42, number 2 OPTICSCOMMUNICATIONS 15 June 1982 ELECTRON BEAM PUMPED CW Se II LASER ~

    E-Print Network [OSTI]

    Rocca, Jorge J.

    Volume 42, number 2 OPTICSCOMMUNICATIONS 15 June 1982 ELECTRON BEAM PUMPED CW Se II LASER ~ J of singlyionized seleniumusingan electron beam to excite a He-Se mixture. The variation of the laser output power as a function of the electron beam dischargeparameters is reported. Recently we obtained cw laser radiation from

  2. Superconductivity in Strong Spin Orbital Coupling Compound Sb2Se3

    E-Print Network [OSTI]

    Shen, Guoyin

    Superconductivity in Strong Spin Orbital Coupling Compound Sb2Se3 P. P. Kong1 , F. Sun1,3 , L. Y induce Sb2Se3 into a topological nontrivial state. Here, we report on the discovery of superconductivity superconductive at high pressures above 10 GPa proceeded by a pressure induced insulator to metal like transition

  3. Photovoltaic cells fabricated by electrophoretic deposition of CdSe nanocrystals

    E-Print Network [OSTI]

    Smith, Nathanael J.

    Photovoltaic cells fabricated by electrophoretic deposition of CdSe nanocrystals Nathanael J. Smith Electrophoretic deposition was used to deposit CdSe nanocrystals on TiO2 for use in photovoltaic cells formed. A solar cell constructed using electrophoretic deposition exhibited a photovoltaic response from

  4. ME/SE 762 Nonlinear Systems and Control Location: SOC B63

    E-Print Network [OSTI]

    Lin, Xi

    ME/SE 762 Nonlinear Systems and Control Location: SOC B63 Time: Tue & Thu 12-2 Instructor: Calin-4 #12;ME/SE 762 Nonlinear Systems and Control Prerequisites: a grad-level class on linear systems: · stability analysis of nonlinear systems (with emphasis on Lyapunov theory) · nonlinear feedback control

  5. Development of a Low Cost Insulated Foil Substrate for Cu(InGaSe)2 Photovoltaics

    SciTech Connect (OSTI)

    ERTEN ESER

    2012-01-22

    The project validated the use of stainless steel flexible substrate coated with silicone-based resin dielectric, developed by Dow Corning Corporation, for Cu(InGa)Se2 based photovoltaics. The projects driving force was the high performance of Cu(InGa)Se2 based photovoltaics coupled with potential cost reduction that could be achieved with dielectric coated SS web substrate.

  6. 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.

  7. Approved Module Information for SE12EM, 2014/5 Module Title/Name: Mathematics for 1st year Engineers Module Code: SE12EM

    E-Print Network [OSTI]

    Neirotti, Juan Pablo

    Engineers Module Code: SE12EM School: Engineering and Applied Science Module Type: Standard Module New (Enhanced Honours) Programmes in which available: BEng Mechanical Engineering Systems. BEng/MEng Electromechanical Engineering. BEng/MEng Mechanical Engineering. BEng Electrical Engineering Systems. BEng

  8. Module Information for SE0SLF, 2015/6 -APPROVED Module Title/Name: Systems and Logistics Foundations Module Code: SE0SLF

    E-Print Network [OSTI]

    Rebollo-Neira, Laura

    Module Information for SE0SLF, 2015/6 - APPROVED Module Title/Name: Systems and Logistics thinking and its role in engineering ? To provide students with a knowledge of the role of logistics in society Module Learning Outcomes: ? To describe the role of systems and logistics in engineering and wider

  9. SE HAN FINALIZADO LOS PREPARATIVOS PARA LA CONFERENCIA NACIONAL DE JUSTICIA MEDIOAMBIENTAL Y PROGRAMA DE FORMACIÓN 2013

    Broader source: Energy.gov [DOE]

    La National Environmental Justice Conference, Inc. (Conferencia de Justicia Medioambiental) se prepara para otro exitoso acontecimiento, ya que se aproxima la Conferencia Nacional de Justicia...

  10. 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.

  11. INCOSE Systems Engineering Handbook v3.2: Improving the Process for SE Practitioners

    SciTech Connect (OSTI)

    R. Douglas Hamelin; David D. Walden; Michael E. Krueger

    2010-07-01

    The INCOSE Systems Engineering Handbook is the official INCOSE reference document for understanding systems engineering (SE) methods and conducting SE activities. Over the years, the Handbook has evolved to accommodate advances in the SE discipline and now serves as the basis for the Certified Systems Engineering Professional (CSEP) exam. Due to its evolution, the Handbook had become somewhat disjointed in its treatment and presentation of SE topics and was not aligned with the latest version of International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC) 15288:2008, Systems and Software Engineering. As a result, numerous inconsistencies were identified that could confuse practitioners and directly impact the probability of success in passing the CSEP exam. Further, INCOSE leadership had previously submitted v3.1 of the Handbook to ISO/IEC for consideration as a Technical Report, but was told that the Handbook would have to be updated to conform with the terminology and structure of new ISO/IEC15288:2008, Systems and software engineering, prior to being considered. The revised INCOSE Systems Engineering Handbook v3.2 aligns with the structure and principles of ISO/IEC 15288:2008 and presents the generic SE life-cycle process steps in their entirety, without duplication or redundancy, in a single location within the text. As such, the revised Handbook v3.2 serves as a comprehensive instructional and reference manual for effectively understanding SE processes and conducting SE and better serves certification candidates preparing for the CSEP exam.

  12. Characterization of ZnSe scintillating bolometers for Double Beta Decay

    E-Print Network [OSTI]

    C. Arnaboldi; S. Capelli; O. Cremonesi; L. Gironi; M. Pavan; G. Pessina; S. Pirro

    2010-06-30

    ZnSe scintillating bolometers are good candidates for future Double Beta Decay searches, because of the 82Se high Q-value and thanks to the possibility of alpha background rejection on the basis of the scintillation signal. In this paper we report the characteristics and the anomalies observed in an extensive study of these devices. Among them, an unexpected high emission from alpha particles, accompanied with an unusual pattern of the light vs. heat scatter plot. The perspectives for the application of this kind of detectors to search for the Neutrinoless Double Beta Decay of 82Se are presented.

  13. Ann bay lodyans 11 / Se Bryant Freeman ("Tonton Liben") ki pare ti liv sa a

    E-Print Network [OSTI]

    Freeman, Bryant C.

    2000-01-01

    Liben”) ki pare ti liv sa a. [Lawrence, Kan.] : Institute of Haitian Studies ; [Port-au-Prince] : Bon Nouvèl : Fondasyon Alfa Lwès, 2000. Terms of Use: http://www2.ku.edu/~scholar/docs/license.shtml ANN BAY LODYANS 11 Se Bryant Freeman ("Tonton Liben...") ki pare ti liv sa a. AYITI SE PEP AYISYEN PM 7854 .H39 A56 2000 PM Enstiti Etid Ayisyen - Inivesite Kannzas Bon Nouvel Fondasyon Alfa Lwes 1997 YON PWASON KI RELE TEZEN Vwala se yon jennfi yo rele Wozilya ak yon jennjan yo rele Tezen ki...

  14. Ann bay lodyans 14 / Se Bryant Freeman ("Tonton Liben") ki pare ti liv sa a

    E-Print Network [OSTI]

    Freeman, Bryant C.

    2000-01-01

    Liben”) ki pare ti liv sa a. [Lawrence, Kan.] : Institute of Haitian Studies ; [Port-au-Prince] : Bon Nouvèl : Fondasyon Alfa Lwès, 2000. Terms of Use: http://www2.ku.edu/~scholar/docs/license.shtml fcjNlVfcHto" r ' K A N S A S L lBf iAH.r ANN BAY... LODYANS1 4 Se Bryant Freeman ("Tonton Liben") ki pare ti liv sa a. A 51* AYITI SE PEP AYISYEN PM 7854 .H39 A56 2000 v. 14 Enstiti Etid Ayisyen - Inivesite Kannzas Bon Nouvel Fondasyon Alfa Lwes 2000 YON TI PYE ZORANJ Se istwa yon ti fi ki...

  15. Lattice dynamics of BaFe2X3(X=S,Se) compounds

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

    Popovi?, Z. V.; Š?epanovi?, M.; Lazarevi?, N.; Opa?i?, M.; Radonji?, M. M.; Tanaskovi?, D.; Lei, Hechang; Petrovic, C.

    2015-02-27

    We present the Raman scattering spectra of the S=2 spin ladder compounds BaFe?X? (X=S,Se) in a temperature range between 20 and 400 K. Although the crystal structures of these two compounds are both orthorhombic and very similar, they are not isostructural. The unit cell of BaFe?S? (BaFe?Se?) is base-centered Cmcm (primitive Pnma), giving 18 (36) modes to be observed in the Raman scattering experiment. We have detected almost all Raman active modes, predicted by factor group analysis, which can be observed from the cleavage planes of these compounds. Assignment of the observed Raman modes of BaFe?S(Se)? is supported by themore »lattice dynamics calculations. The antiferromagnetic long-range spin ordering in BaFe?Se? below TN=255K leaves a fingerprint both in the A1g and B3g phonon mode linewidth and energy.« less

  16. Low-temperature ferromagnetic properties in Co-doped Ag{sub 2}Se nanoparticles

    SciTech Connect (OSTI)

    Yang, Fengxia E-mail: xia9020@hust.edu.cn; Yu, Gen; Han, Chong; Liu, Tingting; Zhang, Duanming; Xia, Zhengcai E-mail: xia9020@hust.edu.cn

    2014-01-06

    ?-Ag{sub 2}Se is a topologically nontrivial insulator. The magnetic properties of Co-doped Ag{sub 2}Se nanoparticles with Co concentrations up to 40% were investigated. The cusp of zero-field-cooling magnetization curves and the low-temperature hysteresis loops were observed. With increasing concentration of Co{sup 2+} ions mainly substituting Ag{sub I} sites in the Ag{sub 2}Se structure, the resistivity, Curie temperature T{sub c}, and magnetization increased. At 10?T, a sharp drop of resistance near T{sub c} was detected due to Co dopants. The ferromagnetic behavior in Co-doped Ag{sub 2}Se might result from the intra-layer ferromagnetic coupling and surface spin. This magnetic semiconductor is a promising candidate in electronics and spintronics.

  17. Enhanced Thermoelectric Power and Electronic Correlations in RuSe2

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

    Wang, Kefeng; Wang, Aifeng; Tomic, A.; Wang, Limin; Abeykoon, A.M. Milinda; Dooryhee, E.; Billinge, S. J.L.; Petrovic, C.

    2015-04-01

    We report the electronic structure, electric and thermal transport properties of Ru1-xIrxSe2 (x ? 0:2). RuSe2 is a semiconductor that crystallizes in a cubic pyrite unit cell. The Seebeck coefficient of RuSe2 exceeds -200 ?#22;V/K around 730 K. Ir substitution results in the suppression of the resistivity and the Seebeck coefficient, suggesting the removal of the peaks in density of states near the Fermi level. Ru0.8Ir0.2Se2 shows a semiconductor-metal crossover at about 30 K. The magnetic field restores the semiconducting behavior. Our results indicate the importance of the electronic correlations in enhanced thermoelectricity of RuSb2.

  18. Phonon properties of BaFe?X? (X=S, Se) spin ladder compounds

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

    Popovicq, Z. V.; Petrovic, C.; Scepanovic, M.; Lazarevic, N.; Opacic, M.; Radonjic, M. M.; Tanaskovic, D.; Lei, Hechang

    2015-02-27

    We present the Raman scattering spectra of the S=2 spin ladder compounds BaFe?X? (X=S,Se) in a temperature range between 20 and 400 K. Although the crystal structures of these two compounds are both orthorhombic and very similar, they are not isostructural. The unit cell of BaFe?S? (BaFe?Se?) is base-centered Cmcm (primitive Pnma), giving 18 (36) modes to be observed in the Raman scattering experiment. We have detected almost all Raman active modes, predicted by factor group analysis, which can be observed from the cleavage planes of these compounds. Assignment of the observed Raman modes of BaFe?S(Se)? is supported by themore »lattice dynamics calculations. The antiferromagnetic long-range spin ordering in BaFe?Se? below TN=255K leaves a fingerprint both in the A1g and B3g phonon mode linewidth and energy.« less

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

    Office of Scientific and Technical Information (OSTI)

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

  20. Time resolved fluorescence of CdSe nanocrystals using single molecule spectroscopy

    E-Print Network [OSTI]

    Fisher, Brent R

    2005-01-01

    A wide variety of spectroscopic studies of CdSe nanocrystals (NCs) are presented in this thesis, all studying some aspect of the temporal evolution of NC fluorescence tinder different conditions. In particular the methods ...

  1. Synthesis and structural characterization of ZnTe/ZnSe core/shell tunable quantum dots

    E-Print Network [OSTI]

    Guan, Juan

    2008-01-01

    Colloidal semiconductor nanocrystals or quantum dots have attracted much attention recently with their unique optical properties. Here we present a novel approach to synthesize ZnTe/ZnSe core/shell tunable quantum dots. ...

  2. Efficient light emitting devices utilizing CdSe(ZnS) quantum dots in organic host matrices

    E-Print Network [OSTI]

    Coe-Sullivan, Seth (Seth Alexander)

    2002-01-01

    We demonstrate efficient electroluminescence from thin film structures containing core-shell CdSe(ZnS) quantum dots dispersed in molecular organic host materials. In the most efficient devices, excitons are created on the ...

  3. WEATHERIZATION INDUSTRIES SAVE ENERGY ST SE SALEM, OREGON 97301 (503) 5691381 WEATHERIZATIONALLIES@GMAIL.COM

    E-Print Network [OSTI]

    WEATHERIZATION INDUSTRIES SAVE ENERGY 565 21ST ST SE SALEM, OREGON 97301 · (503) 5691381 AND CONSERVATION COUNCIL'S CONSERVATION PLANNING ASSUMPTIONS Weatherization Industries Save Energy (WISE · WEATHERIZATIONALLIES@GMAIL.COM COMMENTS ON ACHIEVABLE SAVINGS: A RETROSPECTIVE LOOK AT THE NORTHWEST POWER

  4. Hidden Superlattice in Tl2(SC6H4S) and Tl2(SeC6H4Se) Solved from Powder X-ray Diffraction

    SciTech Connect (OSTI)

    K Stone; D Turner; M Singh; T Vaid; P Stephens

    2011-12-31

    The crystal structures of the isostructural title compounds poly[({mu}-benzene-1,4-dithiolato)dithallium], Tl{sub 2}(SC{sub 6}H{sub 4}S), and poly[({mu}-benzene-1,4-diselenolato)dithallium], Tl{sub 2}(SeC{sub 6}H{sub 4}Se), were solved by simulated annealing from high-resolution synchrotron X-ray powder diffraction. Rietveld refinements of an initial structure with one formula unit per triclinic cell gave satisfactory agreement with the data, but led to a structure with impossibly close non-bonded contacts. A disordered model was proposed to alleviate this problem, but an alternative supercell structure leads to slightly improved agreement with the data. The isostructural superlattice structures were confirmed for both compounds through additional data collection, with substantially better counting statistics, which revealed the presence of very weak superlattice peaks not previously seen. Overall, each structure contains Tl-S or Tl-Se two-dimensional networks, connected by phenylene bridges. The sulfur (or selenium) coordination sphere around each thallium is a highly distorted square pyramid or a 'see-saw' shape, depending upon how many Tl-S or Tl-Se interactions are considered to be bonds. In addition, the two compounds contain pairs of Tl{sup I} ions that interact through a closed-shell 'thallophilic' interaction: in the sulfur compound there are two inequivalent pairs of Tl atoms with Tl-Tl distances of 3.49 and 3.58 {angstrom}, while in the selenium compound those Tl-Tl interactions are at 3.54 and 3.63 {angstrom}.

  5. Thin-film Sb2Se3 photovoltaics with oriented one-dimensional ribbons and benign

    E-Print Network [OSTI]

    Sargent, Edward H. "Ted"

    to the substrate, and produced Sb2Se3 thin-film solar cells with a certified device efficiency of 5.6%. Our results are one of the major limiting factors for high-efficiency thin-film solar cells. We began with first cells based on inorganic absorbers, such as Si, GaAs, CdTe and Cu(In,Ga)Se2, permit a high device

  6. 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.

  7. Novel Approaches to Wide Bandgap CuInSe2 Based Absorbers

    SciTech Connect (OSTI)

    William N. Shafarman

    2011-04-28

    This project targeted the development of high performance wide bandgap solar cells based on thin film alloys of CuInSe2 to relax constraints on module design and enable tandem solar cell structures. This addressed goals of the Solar Energy Technologies Program for Next Generation PV to develop technology needed for higher thin film module efficiency as a means to reduce costs. Specific objectives of the research project were: 1) to develop the processes and materials required to improve the performance of wide bandgap thin film solar cells based on alloys of CuInSe2, and 2) to provide the fundamental science and engineering basis for the material, electronic, and device properties required to effectively apply these processes and materials to commercial manufacture. CuInSe2-based photovoltaics have established the highest efficiencies of the thin film materials at both the cell and module scales and are actively being scaled up to commercialization. In the highest efficiency cells and modules, the optical bandgap, a function of the CuInSe2-based alloy composition, is relatively low compared to the optimum match to the solar spectrum. Wider bandgap alloys of CuInSe2 produce higher cell voltages which can improve module performance and enable the development of tandem solar cells to boost the overall efficiency. A focus for the project was alloying with silver to form (AgCu)(InGa)Se2 pentenary thin films deposited by elemental co-evaporation which gives the broadest range of control of composition and material properties. This alloy has a lower melting temperature than Ag-free, Cu-based chalcopyrite compounds, which may enable films to be formed with lower defect densities and the (AgCu)(InGa)Se2 films give improved material properties and better device performance with increasing bandgap. A comprehensive characterization of optical, structural, and electronic properties of (AgCu)(InGa)Se2 was completed over the complete compositional range 0 ? Ga/(In+Ga) ? 1 and 0 ? Ag/(Ag+Cu) ? 1. Evidence of improved material quality includes reduced sub-bandgap optical absorption, sharper bandtails, and increased grain size with Ag addition. The Ag alloying was shown to increase the range of bandgaps over which solar cells can be fabricated without any drop-off in performance. With bandgap greater than 1.6 eV, in the range needed for tandem solar cells, (AgCu)(InGa)Se2 gave higher efficiency than other CuInSe2-based alloys. Using a simple single-stage co-evaporation process, a solar cell with 17.6% efficiency using a film with bandgap = 1.3 eV was achieved, demonstrating the viability of (AgCu)(InGa)Se2 for high efficiency devices. With a three-stage co-evaporation process for (AgCu)(InGa)Se2 deposition a device with efficiency = 13.0 % and VOC = 890 mV with JSC = 20.5 mA/cm2, FF = 71.3% was achieved. This surpasses the performance of other wide bandgap CuInSe2-based solar cells. Detailed characterization of the electronic properties of the materials and devices including the application of advanced admittance-based easements was completed.

  8. Electronic structure, irreversibility line and magnetoresistance of Cu0.3Bi2Se3 superconductor

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

    Hemian, Yi; Gu, Genda; Chen, Chao -Yu; Sun, Xuan; Xie, Zhuo -Jin; Feng, Ya; Liang, Ai -Ji; Peng, Ying -Ying; He, Shao -Long; Zhao, Lin; et al

    2015-06-01

    CuxBi2Se3 is a superconductor that is a potential candidate for topological superconductors. We report our laser-based angle-resolved photoemission measurement on the electronic structure of the CuxBi2Se3 superconductor, and a detailed magneto-resistance measurement in both normal and superconducting states. We find that the topological surface state of the pristine Bi2Se3 topological insulator remains robust after the Cu-intercalation, while the Dirac cone location moves downward due to electron doping. Detailed measurements on the magnetic field-dependence of the resistance in the superconducting state establishes an irreversibility line and gives a value of the upper critical field at zero temperature of ~4000 Oe formore »the Cu0.3Bi2Se3 superconductor with a middle point Tc of 1.9K. The relation between the upper critical field Hc2 and temperature T is different from the usual scaling relation found in cuprates and in other kinds of superconductors. Small positive magneto-resistance is observed in Cu0.3Bi2Se3 superconductors up to room temperature. As a result, these observations provide useful information for further study of this possible candidate for topological superconductors.« less

  9. Superconductivity in Strong Spin Orbital Coupling Compound Sb2Se3

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

    Kong, P. P.; Sun, F.; Xing, L. Y.; Zhu, J.; Zhang, S. J.; Li, W. M.; Liu, Q. Q.; Wang, X. C.; Feng, S. M.; Yu, X. H.; et al

    2015-02-17

    Recently, A2B3 type strong spin orbital coupling compounds such as Bi2Te3, Bi2Se3 and Sb2Te3 were theoretically predicated to be topological insulators and demonstrated through experimental efforts. The counterpart compound Sb2Se3 on the other hand was found to be topological trivial, but theoretical studies indicated that the pressure might induce Sb2Se3 into a topological nontrivial state. We report on the discovery of superconductivity in Sb2Se3 single crystal induced via pressure. Our experiments indicated that Sb2Se3 became superconductive at high pressures above 10 GPa proceeded by a pressure induced insulator to metal like transition at ~3 GPa which should be related tomore »the topological quantum transition. The superconducting transition temperature (TC) increased to around 8.0 K with pressure up to 40 GPa while it keeps ambient structure. High pressure Raman revealed that new modes appeared around 10 GPa and 20 GPa, respectively, which correspond to occurrence of superconductivity and to the change of TC slop as the function of high pressure in conjunction with the evolutions of structural parameters at high pressures.« less

  10. In-situ surface composition measurements of CuGaSe{sub 2} thin films

    SciTech Connect (OSTI)

    Fons, P.; Yamada, A.; Niki, S.; Oyanagi, H.

    1998-12-31

    Two CuGaSe{sub 2} films were grown by molecular beam epitaxy onto GaAs (001) substrates with varying Cu/Ga flux ratios under Se overpressure conditions. Growth was interrupted at predetermined times and the surface composition was measured using Auger electron spectroscopy after which growth was continued. After growth, the film composition was analyzed using voltage dependent electron microprobe spectroscopy. Film structure and morphology were also analyzed using x-ray diffraction and atomic force microscopy. The film with a Cu/Ga ratio larger than unity showed evidence of surface segregation of a second Cu-rich phase with a Cu/Se composition ratio slightly greater than unity. A second CuGaSe{sub 2} film with a Cu/Ga ratio of less than unity showed no change in surface composition with time and was also consistent with bulk composition measurements. Diffraction measurements indicated a high concentration of twins as well as the presence of domains with mixed c and a axes in the Ga-rich film. The Cu-rich films by contrast were single domain and had a narrower mosaics. High sensitivity scans along the [001] reciprocal axis did not exhibit any new peaks not attributable to either the substrate or the CuGaSe{sub 2} thin film.

  11. A Novel and Functional Single Layer Sheet of ZnSe

    SciTech Connect (OSTI)

    Zhou, Jia [ORNL; Sumpter, Bobby G [ORNL; Kent, Paul R [ORNL; Huang, Jingsong [ORNL

    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 to other group II-VI analogues.

  12. Charge-transfer dynamics in multilayered PbS and PbSe quantum dot architectures

    SciTech Connect (OSTI)

    Xu, F.; Ma, X.; Haughn, C. R.; Doty, M. F.; Cloutier, S. G.

    2014-02-03

    We demonstrate control of the charge transfer process in PbS and PbSe quantum dot assemblies. We first demonstrate efficient charge transfer from donor quantum dots to acceptor quantum dots in a multi-layer PbSe cascade structure. Then, we assemble type-I and type-II heterostructures using both PbS and PbSe quantum dots via careful control of the band alignment. In type-I structures, photo-generated carriers are transferred and localized in the smaller bandgap (acceptor) quantum dots, resulting in a significant luminescence enhancement. In contrast, a significant luminescence quenching and shorter emission lifetime confirms an efficient separation of photo-generated carriers in the type-II architecture.

  13. 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

  14. Substrate induced modulation of electronic, magnetic and chemical properties of MoSe{sub 2} monolayer

    SciTech Connect (OSTI)

    Wasey, A. H. M. Abdul; Chakrabarty, Soubhik; Das, G. P., E-mail: msgpd@iacs.res.in [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032 (India)

    2014-04-15

    Monolayer of MoSe{sub 2}, having a typical direct band gap of ?1.5 eV, is a promising material for optoelectronic and solar cell applications. When this 2D semiconductor is supported on transition metal substrates, such as Ni(111) and Cu(111), its electronic structure gets modulated. First principles density functional investigation shows the appearance of de-localized mid-gap states in the density of states. The work function of the semiconductor overlayer gets modified considerably, indicating n-type doping caused by the metal contacts. The charge transfer across the metal-semiconductor junction also significantly enhances the chemical reactivity of the MoSe{sub 2} overlayer, as observed by Hydrogen absorption. Furthermore, for Ni contact, there is a signature of induced magnetism in MoSe{sub 2} monolayer.

  15. 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.

  16. 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.

  17. 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.

  18. Two-step growth of two-dimensional WSe2/MoSe2 heterostructures

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

    Gong, Yongji; Lei, Sidong; Lou, Jun; Liu, Zheng; Vajtai, Robert; Zhou, Wu; Ajayan, Pullikel M.

    2015-08-03

    Two dimensional (2D) materials have attracted great attention due to their unique properties and atomic thickness. Although various 2D materials have been successfully synthesized with different optical and electrical properties, a strategy for fabricating 2D heterostructures must be developed in order to construct more complicated devices for practical applications. Here we demonstrate for the first time a two-step chemical vapor deposition (CVD) method for growing transition-metal dichalcogenide (TMD) heterostructures, where MoSe2 was synthesized first and followed by an epitaxial growth of WSe2 on the edge and on the top surface of MoSe2. Compared to previously reported one-step growth methods, thismore »two-step growth has the capability of spatial and size control of each 2D component, leading to much larger (up to 169 ?m) heterostructure size, and cross-contamination can be effectively minimized. Furthermore, this two-step growth produces well-defined 2H and 3R stacking in the WSe2/MoSe2 bilayer regions and much sharper in-plane interfaces than the previously reported MoSe2/WSe2 heterojunctions obtained from one-step growth methods. The resultant heterostructures with WSe2/MoSe2 bilayer and the exposed MoSe2 monolayer display rectification characteristics of a p-n junction, as revealed by optoelectronic tests, and an internal quantum efficiency of 91% when functioning as a photodetector. As a result, a photovoltaic effect without any external gates was observed, showing incident photon to converted electron (IPCE) efficiencies of approximately 0.12%, providing application potential in electronics and energy harvesting.« less

  19. Ann bay lodyans 13 / Se Bryant Freeman ("Tonton Liben") ki pare ti liv sa a

    E-Print Network [OSTI]

    Freeman, Bryant C.

    2000-01-01

    , li pa kite anyen deye. Mouche ale ak ni jwet zo li, ni kat li, ni boutey tafya, menm ti bout tanbou a li pa bliye mete. Konsa, kon mouche rive anwo a, li tabli yon jwet zo ak yon jwet kat, ansanm ak yon konmes kleren. Sa fe, pyes travay pa ka fet... sa a se yon danje piblik. Fok yo jwenn bout li. Depi Telisfo vini an, lanfe a vin tounen yon peyi pleziyis. Abitan yo pwofite fe parese. Men tou, Telisfo pa kite yo gen anyen, menm bout sigaret pa ka rete. Sa ki pi red, se chak jou yon moun...

  20. Ann bay lodyans 6 / se Bryant Freeman ("Tonton Liben") ki pare ti liv sa a

    E-Print Network [OSTI]

    Freeman, Bryant C.

    2000-01-01

    ("Tonton Liben") ki pare ti liv sa a. AYITI SE PEP AYISYEN PM 7 8 5 4 .H39 A 5 6 2 0 0 0 V . 6 Enstiti Etid Ayisyen - Inivesite Kannzas Bon Nouvel Fondasyon Alfa Lwes 1997 PINGALOT AK ELIFET Vwala te gen yon wa ki rele Pingalot. Men wa sa a... te yon neg sitelman rayisab tout peyi a t ap soufri. Nan peyi sa a te gen yon msye ki rele Elifet. Se te yon bon moun ki te konn travay di, e ki te fe ekonomi jous li rive monte yon gwo kay menm pi bel pase kay wa a. Konsa, Pingalot moveanpil...

  1. Potential thermoelectric performance from optimization of hole-doped Bi2Se3

    SciTech Connect (OSTI)

    Parker, David S [ORNL; Singh, David J [ORNL

    2011-01-01

    We present an analysis of the potential thermoelectric performance of hole-doped Bi2Se3, which is commonly considered to show inferior room temperature performance when compared to Bi2Te3. We find that if the lattice thermal conductivity can be reduced by nanostructuring techniques (as have been applied to Bi2Te3) the material may show optimized ZT values of unity or more in the 300 - 500 K temperature range and thus be suitable for cooling and moderate temperature waste heat recovery and thermoelectric solar cell applications. Central to this conclusion are the larger band gap and the relatively heavier valence bands of Bi2Se3.

  2. Ann bay lodyans 4 / se Bryant Freeman ("Tonton Liben") ki pare ti liv sa a

    E-Print Network [OSTI]

    Freeman, Bryant C.

    2000-01-01

    KU ScholarWorks | http://kuscholarworks.ku.edu Ann Bay Lodyans 4 se Bryant Freeman (“Tonton Liben”) ki pare ti liv sa a 2000 by Bryant C. Freeman, ed. This work has been made available by the University of Kansas Libraries’ Office of Scholarly... Freeman (“Tonton Liben”) ki pare ti liv sa a. [Lawrence, Kan.] : Institute of Haitian Studies ; [Port-au-Prince] : Bon Nouvèl : Fondasyon Alfa Lwès, 2000. Terms of Use: http://www2.ku.edu/~scholar/docs/license.shtml Tl CHAT: PI PITI PI RED Vwala se te...

  3. Ann bay lodyans 1 / se Bryant Freeman ("Tonton Liben") ki pare ti liv sa a

    E-Print Network [OSTI]

    Freeman, Bryant C.

    2000-01-01

    KU ScholarWorks | http://kuscholarworks.ku.edu Ann Bay Lodyans 1 se Bryant Freeman (“Tonton Liben”) ki pare ti liv sa a 2000 by Bryant C. Freeman, ed. This work has been made available by the University of Kansas Libraries’ Office of Scholarly... Freeman (“Tonton Liben”) ki pare ti liv sa a. [Lawrence, Kan.] : Institute of Haitian Studies ; [Port-au-Prince] : Bon Nouvèl : Fondasyon Alfa Lwès, 2000. Terms of Use: http://www2.ku.edu/~scholar/docs/license.shtml ANN BAY LODYANS 1 Se Bryant Freeman...

  4. Pair correlations in nuclei involved in neutrinoless double beta decay: 76Ge and 76Se

    E-Print Network [OSTI]

    S. J. Freeman; J. P. Schiffer; A. C. C. Villari; J. A. Clark; C. Deibel; S. Gros; A. Heinz; D. Hirata; C. L. Jiang; B. P. Kay; A. Parikh; P. D. Parker; J. Qian; K. E. Rehm; X. D. Tang; V. Werner; C. Wrede

    2007-03-23

    Precision measurements were carried out to test the similarities between the ground states of 76Ge and 76Se. The extent to which these two nuclei can be characterized as consisting of correlated pairs of neutrons in a BCS-like ground state was studied. The pair removal (p,t) reaction was measured at the far forward angle of 3 degrees. The relative cross sections are consistent (at the 5% level) with the description of these nuclei in terms of a correlated pairing state outside the N=28 closed shells with no pairing vibrations. Data were also obtained for 74Ge and 78Se.

  5. Ann bay lodyans 15 / Se Bryant Freeman ("Tonton Liben") ki pare ti liv sa a

    E-Print Network [OSTI]

    Freeman, Bryant C.

    2000-01-01

    Liben”) ki pare ti liv sa a. [Lawrence, Kan.] : Institute of Haitian Studies ; [Port-au-Prince] : Bon Nouvèl : Fondasyon Alfa Lwès, 2000. Terms of Use: http://www2.ku.edu/~scholar/docs/license.shtml ANN BAY LODYANS15 Se Bryant Freeman ("Tonton Liben...") ki pare ti liv sa a. H ^ AYITI SE PEP AYISYEN 2 0 0 0 Enstiti Etid Ayisyen - Inivesite Kannzas Bon Nouvel Fondasyon Alfa Lwes 2000 PM 7854 .H39 A56 2000 v. 15 YON KONTRA AK LEDJAB Vwala te gen yon malerez ki te deja gen douz pitit, e...

  6. Ann bay lodyans 5 / se Bryant Freeman ("Tonton Liben") ki pare ti liv sa a

    E-Print Network [OSTI]

    Freeman, Bryant C.

    2000-01-01

    Liben”) ki pare ti liv sa a. [Lawrence, Kan.] : Institute of Haitian Studies ; [Port-au-Prince] : Bon Nouvèl : Fondasyon Alfa Lwès, 2000. Terms of Use: http://www2.ku.edu/~scholar/docs/license.shtml ANN BAY LODYANS 5 Se Bryant Freeman ("Tonton Liben.... Tijo we yon tig ki te tonbe nan yon gwo twou. Li pa t kapab soti paske twou a fon. Kounye a tig la prizonye. Li di Tijo: "Ou se yon bon ti gason, ede m soti, souple." Tijo reponn: "Si mwen retire ou nan twou a, ou ap manje m." Tig la di: "O non...

  7. Ann bay lodyans 3 / se Bryant Freeman ("Tonton Liben") ki pare ti liv sa a

    E-Print Network [OSTI]

    Freeman, Bryant C.

    2000-01-01

    Liben”) ki pare ti liv sa a. [Lawrence, Kan.] : Institute of Haitian Studies ; [Port-au-Prince] : Bon Nouvèl : Fondasyon Alfa Lwès, 2000. Terms of Use: http://www2.ku.edu/~scholar/docs/license.shtml ANN BAY LODYANS 3 Se Bryant Freeman ("Tonton Liben...") ki pare ti liv sa a. AYITI SE PEP AYISYEN Enstiti Etid Ayisyen - Inivesite Kannzas Bon Nouvel Fondasyon Alfa Lwes 2000 PM 7854 • H39 A56 KUAN POU M JWENN KOB? Vwala te gen yon zarenyen ki te raze net. Li di nan tet li: "M bezwen jwenn kob...

  8. Ann bay lodyans 16 / Se Bryant Freeman ("Tonton Liben") ki pare ti liv sa a

    E-Print Network [OSTI]

    Freeman, Bryant C.

    2000-01-01

    ofisye yo. Genyen yon gwo pyano pou nou pote nan sal la." Pye Wolen, Senlwidino TET DESALIN Yon blan rantre an Ayiti. Li mande yon neg: "Fe m jwenn tet Jan Jak Desalin, pou souvni." Neg la, sa li gen pou fe, li rantre nan yon simitye, li pran yon... tet byen vit. Li pote I bay blan an. Blan an di konsa: "Sa a pa tet Desalin. Tet Desalin pa kapab piti konsa." Neg la di: "Sa a se tet Desalin le I te timoun!" 8 MANGO A Ml Se Bouki ak Malis ki t ap pwonmennen. Bouki di Malis: "Men yon pye mango...

  9. Method of fabricating high-efficiency Cu(In,Ga)(SeS).sub.2 thin films for solar cells

    DOE Patents [OSTI]

    Noufi, Rommel (Golden, CO); Gabor, Andrew M. (Boulder, CO); Tuttle, John R. (Denver, CO); Tennant, Andrew L. (Denver, CO); Contreras, Miguel A. (Golden, CO); Albin, David S. (Denver, CO); Carapella, Jeffrey J. (Evergreen, CO)

    1995-01-01

    A process for producing a slightly Cu-poor thin film of Cu(In,Ga)(Se,S).sub.2 comprises depositing a first layer of (In,Ga).sub.x (Se,S).sub.y followed by depositing just enough Cu+(Se,S) or Cu.sub.x (Se,S) to produce the desired slightly Cu-poor material. In a variation, most, but not all, (about 90 to 99%) of the (In,Ga).sub.x (Se,S).sub.y is deposited first, followed by deposition of all the Cu+(Se,S) or Cu.sub.x (Se,S) to go near stoichiometric, possibly or even preferably slightly Cu-rich, and then in turn followed by deposition of the remainder (about 1 to 10%) of the (In,Ga).sub.x (Se,S).sub.y to end with a slightly Cu-poor composition. In yet another variation, a small portion (about 1 to 10%) of the (In,Ga).sub.x (Se,S).sub.y is first deposited as a seed layer, followed by deposition of all of the Cu+(Se,S) or Cu.sub.x (Se,S) to make a very Cu-rich mixture, and then followed deposition of the remainder of the (In,Ga).sub.x (Se,S).sub.y to go slightly Cu-poor in the final Cu(In,Ga)(Se,S).sub.2 thin film.

  10. Method of fabricating high-efficiency Cu(In,Ga)(Se,S){sub 2} thin films for solar cells

    DOE Patents [OSTI]

    Noufi, R.; Gabor, A.M.; Tuttle, J.R.; Tennant, A.L.; Contreras, M.A.; Albin, D.S.; Carapella, J.J.

    1995-08-15

    A process for producing a slightly Cu-poor thin film of Cu(In,Ga)(Se,S){sub 2} comprises depositing a first layer of (In,Ga){sub x} (Se,S){sub y} followed by depositing just enough Cu+(Se,S) or Cu{sub x} (Se,S) to produce the desired slightly Cu-poor material. In a variation, most, but not all, (about 90 to 99%) of the (In,Ga){sub x} (Se,S){sub y} is deposited first, followed by deposition of all the Cu+(Se,S) or Cu{sub x} (Se,S) to go near stoichiometric, possibly or even preferably slightly Cu-rich, and then in turn followed by deposition of the remainder (about 1 to 10%) of the (In,Ga){sub x} (Se,S){sub y} to end with a slightly Cu-poor composition. In yet another variation, a small portion (about 1 to 10%) of the (In,Ga){sub x} (Se,S){sub y} is first deposited as a seed layer, followed by deposition of all of the Cu+(Se,S) or Cu{sub x} (Se,S) to make a very Cu-rich mixture, and then followed deposition of the remainder of the (In,Ga){sub x} (Se,S){sub y} to go slightly Cu-poor in the final Cu(In,Ga)(Se,S){sub 2} thin film. 5 figs.

  11. Analysis of chemically deposited CdSe and CdS thin films

    E-Print Network [OSTI]

    Osuji, R U

    2002-01-01

    We have successfully deposited quality polycrystalline thin films of CdSe and CdS on Corning 7059 glass slides by the electroless chemical bath technique at room temperature (~27 $^\\circ$C). X-ray analysis confirmed the successful deposition of CdSe and CdS thin films. Our grown CdSe film thickness ranged from 0.10 $\\mu$m. to 0.80 $\\pm$ 0.01 $\\mu$m and the CdS film thickness ranged from 0.10 $\\mu$m to 1.00 $\\pm$ 0.01 $\\mu$m. The scanning electron micrograph of the films reveals uniform film surface. The energy gaps, $E_g$ determined for our CdSe and CdS films have average values of 1.70 $\\pm$ 0.04 eV and 2.15 $\\pm$ 0.04 eV respectively. The films have high absorbance in the 0.35 $\\mu$m - 0.85 $\\mu$m range. These qualities make them suitable for use in thin film solar cell technology.

  12. DISTRIBUTED POSE AVERAGING IN CAMERA NETWORKS VIA CONSENSUS ON SE(3) Roberto Tron, Rene Vidal

    E-Print Network [OSTI]

    DISTRIBUTED POSE AVERAGING IN CAMERA NETWORKS VIA CONSENSUS ON SE(3) Roberto Tron, Ren´e Vidal distributed algorithms for esti- mating the average pose of an object viewed by a localized network of camera networks; pose estimation; consensus; optimization on manifolds. 1. INTRODUCTION Recent hardware

  13. SE-LEGO: Creating Metasearch Engines on Demand Zonghuan Wu, Vijay Raghavan,

    E-Print Network [OSTI]

    Meng, Weiyi

    SE-LEGO: Creating Metasearch Engines on Demand Zonghuan Wu, Vijay Raghavan, Chun Du, Komanduru Sai Keywords: Metasearch Engine, Metasearcher, search engine Extended Abstract As a system that provides unified access to multiple existing search systems, a metasearch engine can alleviate ordinary users from

  14. Long FRC Equilibrium and Stability Toward a Theory of S*/E Scaling D. C. Barnes*

    E-Print Network [OSTI]

    Washington at Seattle, University of

    Long FRC Equilibrium and Stability ­ Toward a Theory of S*/E Scaling D. C. Barnes* Los Alamos-reversed configurations (FRC's) is solved by an expansion in the small parameter (inverse elongation). The main results, to appear Phys. Plasmas]; 2) there are two classes of potentially unstable modes, transverse and axial, both

  15. T-558: Oracle Java SE and Java for Business Critical Patch Update Advisory- February 2011

    Broader source: Energy.gov [DOE]

    This Critical Patch Update contains 21 new security fixes for Oracle Java SE and Java for Business. 19 of these vulnerabilities may be remotely exploitable without authentication, i.e., may be exploited over a network without the need for a username and password.

  16. T-641: Oracle Java SE Critical Patch Update Advisory- June 2011

    Broader source: Energy.gov [DOE]

    This Critical Patch Update contains 17 new security fixes for Oracle Java SE - 5 apply to client and server deployments of Java SE, 11 apply to client deployments of Java SE only, and 1 applies to server deployments of Java SE only. All of these vulnerabilities may be remotely exploitable without authentication, i.e., may be exploited over a network without the need for a username and password. Oracle CVSS scores assume that a user running a Java applet or Java Web Start application has administrator privileges (typical on Windows). Where the user does not run with administrator privileges (typical on Solaris and Linux), the corresponding CVSS impact scores for Confidentiality, Integrity, and Availability are "Partial" instead of "Complete", and the corresponding CVSS Base score is 7.5 instead of 10 respectively. For issues in Deployment, fixes are only made available for JDK and JRE 6. Users should use the Java Web Start in JRE 6 and the new Java Plug-in introduced in 6 Update 10. CVE-2011-0862, CVE-2011-0873, CVE-2011-0815, CVE-2011-0817, CVE-2011-0863, CVE-2011-0864, CVE-2011-0802, CVE-2011-0814, CVE-2011-0871, CVE-2011-0786, CVE-2011-0788, CVE-2011-0866, CVE-2011-0868, CVE-2011-0872, CVE-2011-0867, CVE-2011-0869, and CVE-2011-0865

  17. FI 10 19 dcembre 2006 page Alan Turing se fraye un chemin jusqu'

    E-Print Network [OSTI]

    Teuscher, Christof

    FI 10 ­ 19 décembre 2006 ­ page Alan Turing se fraye un chemin jusqu'à la place de lPiccard,cheminJeanTschumi,avenueForel,rue RobertMercier,chemin, place ou rueAlanTuring. EtquefaisaitAlanTuringcheminfaisant?Leplus souvent,craqueurducodesecretdela machineEnigma?Certesexagéré,maisle succèsaplusieursparentsetAlanTuring estaumoinslegrandpèreoul

  18. R. Bchela,b, S.E. Pratsinisa, A. Baikerb Two-Nozzle Flame Synthesis of

    E-Print Network [OSTI]

    Daraio, Chiara

    R. Büchela,b, S.E. Pratsinisa, A. Baikerb Two-Nozzle Flame Synthesis of NOx Storage- Reduction and Bioengineering , ETH Zurich, CH-8092 Zurich, Switzerland NOx storage reduction (NSR) catalysts are used) the corresponding light-off Particle production NOx storage and reduction Objective 0 20 40 60 80 100 3) after

  19. Oceanography Vol.19, No. 3, Sept. 200664 Oceanography Vol.19, No. 3, Se64 Currents, Eddies,

    E-Print Network [OSTI]

    Rhode Island, University of

    Oceanography Vol.19, No. 3, Sept. 200664 Oceanography Vol.19, No. 3, Se64 Currents, Eddies. For a comprehensive re- view of the circulation in the region, see Chang et al. (2004). Oceanography Vol.19, No. 3 ThisarticlehasbeenpublishedinOceanography,Volume19,Number3,aquarterlyjournalofTheOceanographySociety.Copyright2006byTheOceanography

  20. Photovoltaic effect in InSe Application to Solar Energy Conversion

    E-Print Network [OSTI]

    Boyer, Edmond

    253 Photovoltaic effect in InSe Application to Solar Energy Conversion A. Segura, J. P. Guesdon, J are reported. Photovoltaic spectra are fitted with measured values oftransport and optical parameters. In possibilities as a material for photovoltaic cells. Transport in indium selenide shows a large ani- sotropy

  1. El tratamiento con cloro es un mtodo para desinfectar un pozo de agua. Se recomien-

    E-Print Network [OSTI]

    El tratamiento con cloro es un método para desinfectar un pozo de agua. Se recomien- da cuando un sistema de agua está contam- inado con bacterias. La contaminación puede ocurrir en la instalación del exceso de lluvia entran en el pozo. Si el agua subterránea constituye en sí la fuente de bacterias, el

  2. Al tratamiento del agua potable para mejo-rar su sanidad o calidad bacteriolgica se

    E-Print Network [OSTI]

    Al tratamiento del agua potable para mejo- rar su sanidad o calidad bacteriológica se le refiere desinfección usado por los proveedores locales para disminuir la contami- nación bacteriológica del agua. Este método tam- bién puede ser usado por los propietarios de pozos de agua particulares. Pozos de agua Los

  3. Molecular beam epitaxial growth of Bi{sub 2}Se{sub 3} nanowires and nanoflakes

    SciTech Connect (OSTI)

    Knebl, G. M. Gessler, J. R.; Kamp, M.; Höfling, S.

    2014-09-29

    Topological Insulators are in focus of immense research efforts and rapid scientific progress is obtained in that field. Bi{sub 2}Se{sub 3} has proven to be a topological insulator material that provides a large band gap and a band structure with a single Dirac cone at the ?-point. This makes Bi{sub 2}Se{sub 3} one of the most promising three dimensional topological insulator materials. While Bi{sub 2}Se{sub 3} nanowires and nanoflakes so far were fabricated with different methods and for different purposes, we here present the first Bi{sub 2}Se{sub 3} nanowires as well as nanoflakes grown by molecular beam epitaxy. The nanostructures were nucleated on pretreated, silicon (100) wafers. Altering the growth conditions nanoflakes could be fabricated instead of nanowires; both with high crystalline quality, confirmed by scanning electron microscopy as well as transmission electron microscopy. These nanostructures have promise for spintronic devices and Majorana fermion observation in contact to superconductor materials.

  4. Stability of S and Se induced reconstructions on GaP(001)(2×1) surface

    SciTech Connect (OSTI)

    Li , D. F.; Guo, Zhi C.; Xiao, Hai Yan; Zu, Xiaotao T.; Gao, Fei

    2010-10-15

    The structural and electronic properties of S- and Se- passivated GaP(001)(2×1) surfaces were studied using first-principles simulations. Our calculations showed that the most stable structure consists of a single chalcogen atom (S or Se) in the first crystal layer, which is bonded to two Ga atoms of the second layer, and the third P layer replaced by chalcogen atoms, similar to the passivation of GaAs(001)(2×1) surface by chalcogen atoms. The structural parameters were determined and the surface band characters and the local density of states were also analyzed. The results showed that the preferable structure has no surface states in the bulk band gap, but the energy band gaps of the S- and Se-adsorbed GaP(001) surfaces are 1.83eV and 1.63eV, respectively. The passivation effects for the S- and Se-adsorbed surfaces are similar to each other.

  5. A highly efficient (>6%) Cd1xMnxSe quantum dot sensitized solar cell

    E-Print Network [OSTI]

    Cao, Guozhong

    , suffer from high cost of manufacturing and installation. Now the focus is on next generation solar cellsA highly efficient (>6%) Cd1ÀxMnxSe quantum dot sensitized solar cell Jianjun Tian,*a Lili Lv,a Chengbin Fei,b Yajie Wang,b Xiaoguang Liua and Guozhong Cao*bc Quantum dot sensitized solar cells (QDSCs

  6. Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells

    E-Print Network [OSTI]

    Rockett, Angus

    Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells O. Lundberga,*, J. Lua , A conversion efficiency of solar cells made from this material [1]. One of the special qualities of the CIGS improve the solar cell performance. In many of the different CIGS fabrication techniques, an in depth

  7. Tetrapod localities from the Triassic of the SE of European Russia Valentin P. Tverdokhlebova

    E-Print Network [OSTI]

    Benton, Michael

    of the southern Urals area of European Russia. The first sites were found in the 1940s, and subsequent surveys B.V. All rights reserved. Keywords: Permian; Triassic; Tetrapod; Amphibian; Reptile; Russia; UralsTetrapod localities from the Triassic of the SE of European Russia Valentin P. Tverdokhlebova

  8. The Single Most Polymorphic STR Locus: SE33 Performance in U.S. Populations

    E-Print Network [OSTI]

    http://www.cstl.nist.gov/biotech/strbase john.butler@nist.gov http://www.dna.gov/research/nist Buenos of the SE33 repeat region. Poster available for download from STRBase: http://www.cstl.nist.gov/biotech Biotech, Ft. Lauderdale, FL). A total of 400 father-son sample pairs were provided by DNA Diagnostics

  9. Characterization of an FFDM unit based on a-Se direct conversion detector

    E-Print Network [OSTI]

    Lanconelli, Nico

    Characterization of an FFDM unit based on a-Se direct conversion detector Achille Albanese1 of this paper is to investigate the properties of a clinical FFDM unit (Giotto - Image MD, IMS Italy µm. The direct conversion of X-rays into charge provides excellent imaging performance. In this work

  10. U .Se Weather Bureau. Hurricane Daisy, September 30-October 7, 1062

    E-Print Network [OSTI]

    QC 945.2 U .Se Weather Bureau. Hurricane Daisy, September 30- October 7, 1062 #12;National Oceanic and Atmospheric Administration Weather Bureau Hurricane Series ERRATA NOTICE One-1387 November 6,2007 #12;OF COMMERCE WEATHER BUREAU LlBRARY JUL 0 5 2001 121 533 #12;HURRICANE DAISY SEPTEMBER

  11. Electrodeposition of CuGaSe2 from Thiocyanate-Containing Electrolytes

    E-Print Network [OSTI]

    Suni, Ian Ivar

    . Manuscript received September 8, 2010. Published December 2, 2010. CuInxGa1-xSe2 CIGS thin film solar cells- nation velocities.1 Thin film solar cells promise significant economic benefits, because the optical, electrochemical deposition methods may be significantly less expensive for scale-up of thin film solar cells,3

  12. Oceanography Vol.23, No.124 MouNtaiNs iN the se a

    E-Print Network [OSTI]

    Sandwell, David T.

    Oceanography Vol.23, No.124 MouNtaiNs iN the se a The Global seamount Census By Pau l We s sel , DaVi estimates for the global census of seamounts. BathyMetriC seaMouNt stuDies Bill Menard began the modern era

  13. Tunable White-Light-Emitting Mn-Doped ZnSe Nanocrystals Vijay Kumar Sharma,

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    Se-related blue emission (410 and 435 nm), Zn-related defect state green emission (520 nm), and Mn-dopant related for the purpose of generation of photometrically high quality white light while maintaining the energy efficiency is to combine red-, green-, and blue-emitting NCs in an appropriate ratio.1,2 However, when one simply mixes

  14. Hydrogen adsorption on Pd/TiFe (110) surface S.E. Kulkovaa

    E-Print Network [OSTI]

    Kim, Jai Sam

    Hydrogen adsorption on Pd/TiFe (110) surface S.E. Kulkovaa , S.V. Eremeeva,b,*, V.E. Egorushkinc February 2003 by E.L. Ivchenko Abstract Adsorption of hydrogen on the TiFe (110) surface covered. Electronic band structure 1. Introduction The TiFe alloy is an excellent material for hydrogen storage [1

  15. SE-CSE 2009: The Second International Workshop on Software Engineering for Computational Science and Engineering

    E-Print Network [OSTI]

    Carver, Jeffrey C.

    SE-CSE 2009: The Second International Workshop on Software Engineering for Computational Science with the development of Computational Science & Engineering (CS&E) software. This software includes: 1) Scientific, the development of CS&E software has historically attracted little attention from the software engineering

  16. MAE 130A / SE 101A (4 units) Mechanics I: Statics

    E-Print Network [OSTI]

    Fainman, Yeshaiahu

    MAE 130A / SE 101A (4 units) Mechanics I: Statics Class/Laboratory Schedule: four hours of lecture/Materials: 1. Beer and Johnston, Vector Mechanics for Engineers - Statics, McGraw-Hill, 2012, 10th ed. 2. Hibbeler, R.C., "Engineering Mechanics: Statics", Pearson Prentice Hall, 2010, 12th ed. Catalog Description

  17. Statistical Mechanics, CHEM 6481, Fall MWF 10:05-10:55am, MoSE 1224

    E-Print Network [OSTI]

    Sherrill, David

    Statistical Mechanics, CHEM 6481, Fall MWF 10:05-10:55am, MoSE 1224 Course website: T-Square Prerequisites: Advanced quantum mechanics (can be taken concurrently), advanced thermodynamics, multivariate" are considered background material. Required Text: "Introduction to Modern Statistical Mechanics," David Chandler

  18. To appear in JSiSE, 18(2), 2001 July 30, 2001

    E-Print Network [OSTI]

    Matsuda, Noboru

    To appear in JSiSE, 18(2), 2001 July 30, 2001 1. (Intelligent Tutoring System: ITS) () "" 2. Graesser (1995) Chi (2001 to appear) #12;Graesser Chi Graesser 70 Chi Graesser Chi ITS ITS "" 3. (Graesser , 2001 to appear) - Building Dialogue Systems for Tutoring

  19. Crystal structure of the new FeSe1-x superconductor 

    E-Print Network [OSTI]

    Margadonna S.; McDonald M.T.; Kasperkiewicz K.; Mizuguchi Y.; Takano Y.; Fitch A.N.; Suard E.; Prassides K.; Takabayashi Y.

    2008-01-01

    The newly discovered superconductor FeSe1-x (x approximate to 0.08, T-c(onset) approximate to 13.5 K at ambient pressure rising to 27 K at 1.48 GPa) exhibits a structural phase transition from tetragonal to orthorhombic ...

  20. Se cumple la regla de Hamilton? Cuando Charles Darwin propuso la teora de la evo-

    E-Print Network [OSTI]

    Machado, Carlos A.

    de reproducirse. En la naturaleza abundan las muestras de altruismo. Pensemos, por ejemplo, en los parentesco ("kin selection"). Esta tesis la esbozó, a mediados de los años se- senta, William Donald Hamilton reducción de comportamientos agre- sivos o de competencia entre congéneres. El núcleo central de dicha tesis

  1. Mn-Substituted Inorganic-Organic Hybrid Materials Based on ZnSe

    E-Print Network [OSTI]

    Li, Jing

    Mn-Substituted Inorganic-Organic Hybrid Materials Based on ZnSe: Nanostructures That May Lead research that deals with synthesis, characterization, and modification of organic-inorganic hybrid to integrate functional materials that utilize both electron charge and spin.1 Thus, the introduction

  2. Electronic structure of the Si(111):GaSe van der Waals-like surface termination

    E-Print Network [OSTI]

    Olmstead, Marjorie

    Electronic structure of the Si(111):GaSe van der Waals-like surface termination Reiner Rudolph-like surface termination has been determined by angle-resolved photoelectron spectroscopy using photons. This explains both the absence of a surface core-level shift in Si 2p photoelectron spectra of the terminated

  3. Deformation regime variations in an arcuate transpressional orogen (Ribeira belt, SE Brazil) imaged by anisotropy of

    E-Print Network [OSTI]

    Bascou, Jérôme

    Deformation regime variations in an arcuate transpressional orogen (Ribeira belt, SE Brazil) imaged Paulo, Brazil b Laboratoire de Tectonophysique, Universite´ de Montpellier II CNRS, Montpellier, France Instituto de Geocie^ncias, Universidade Federal de Minas Gerais, Minas Gerais, Brazil Received 23 September

  4. Holocene tephra from Iceland and Alaska in SE Greenland Shelf Sediments

    E-Print Network [OSTI]

    Stoner, Joseph

    Holocene tephra from Iceland and Alaska in SE Greenland Shelf Sediments ANNE JENNINGS1*, THORVALDURJW, UK 3 Faculty of Earth Sciences, University of Iceland, Askja, Sturlugata 7, Reykjavi´k 101, Iceland 4 College of Earth Ocean and Atmospheric Sciences, Oregon State University 104 COAS Admin Building

  5. Nanofabrication, Plasmon Enhanced Fluorescence and Photo-oxidation Kinetics of CdSe Nanoparticles 

    E-Print Network [OSTI]

    Chen, Jixin

    2011-08-08

    by these techniques include the metal nanoparticle arrays, and the self-assembled CdSe nanoring arrays. At the same time, the dissertation provides mechanisms and models to describe the physical and chemical nature of these techniques. The second area of this study...

  6. Summary for FT, IT and SE 20th IAEA Fusion Energy Conference

    E-Print Network [OSTI]

    Summary for FT, IT and SE 20th IAEA Fusion Energy Conference 1 - 6 November 2004 Vilamoura on Plasma Physics and controlled Nuclear Fusion Research has been changed to be IAEA Fusion Energy and should be moved to the ultimat goal of utilizing fusion energy for human being in near future

  7. MAE 130C / SE 101C (4 units) Mechanics III: Vibrations

    E-Print Network [OSTI]

    Fainman, Yeshaiahu

    MAE 130C / SE 101C (4 units) Mechanics III: Vibrations Class/Laboratory Schedule: four hours Textbooks/Materials: 1. S.S. Rao: Mechanical Vibrations, 4th ed., Prentice Hall, 2010 2. W.T. Thomson and M.D. Dahleh, Theory of Vibrations with Applications, 5th ed., Prentice Hall, 1997 3. L. Meirovitch

  8. Cu(In,Ga)Se2based Photovoltaics: Challenges and Opportunities

    E-Print Network [OSTI]

    Firestone, Jeremy

    Cu(In,Ga)Se2­based Photovoltaics: Challenges and Opportunities William Shafarman Institute of Energy Conversion University of Delaware #12;Thin Film Photovoltaics Potential for low cost PV using a Thickness K.Kim, et al., IEEE J. Photovoltaics, 3, 446 (2013). 2 µm, 60 min reaction 1 µm, 25 min reaction 0

  9. Contractional deformation of porous sandstone: Insights from the Aztec Sandstone, SE Nevada, USA

    E-Print Network [OSTI]

    Fossen, Haakon

    Contractional deformation of porous sandstone: Insights from the Aztec Sandstone, SE Nevada, USA Available online 19 March 2015 Keywords: Sevier thrusting Porous sandstone deformation Deformation bands Contractional deformation a b s t r a c t Contractional deformation of highly porous sandstones is poorly

  10. Study of light-induced vector changes in the local atomic structure of AsSe glasses by EXAFS

    E-Print Network [OSTI]

    Drabold, David

    Study of light-induced vector changes in the local atomic structure of As­Se glasses by EXAFS G changes in the local structure of As­Se glasses using extended X-ray ab- sorption fine structure (EXAFS

  11. Manufacturable CuIn(Ga)Se{sub 2}-based solar cells via development of co-sputtered CuInSe{sub 2} absorber layers

    SciTech Connect (OSTI)

    Dr. Ingrid Eisgruber

    1999-03-20

    Yield and reproducibility remain issues in CuIn(Ga)Se{sub 2} (CIGS) photovoltaic module fabrication. While small-area cells (<1 cm{sup 2}) over 18% efficient have been reported, the best large-area manufactured devices (>1 ft{sup 2}) are 11% efficient with about 60% yield. If improvements in large-area manufacturing can accomplish 15% efficiency and 90% yield, the result is a doubling in throughput leading to a reduction in cost per watt of over 50%. The challenge now facing the photovoltaics industry is to bring the efficiencies of small-area cells and large-area industrial modules closer together and to raise manufacturing yields.

  12. First-principles molecular-dynamics study of glassy As2Se3 Jun Li and D. A. Drabold

    E-Print Network [OSTI]

    Drabold, David

    static structure factor in the range 2­6 Å 1 . The preferred structural unit is pyramidal AsSe3 loosely on the cluster model8 consisting mostly of pyramidal AsSe3 molecules,9 and the other is the layer structure using a molecular model and several vibrational frequencies were assigned to pyramidal AsSe3

  13. Algorithmically scalable block preconditioner for fully implicit shallow water equations in CAM-SE

    SciTech Connect (OSTI)

    Lott, P Aaron [Lawrence Livermore National Laboratory (LLNL); Woodward, Carol [Lawrence Livermore National Laboratory (LLNL); Evans, Katherine J [ORNL

    2015-01-01

    Performing accurate and efficient numerical simulation of global atmospheric climate models is challenging due to the disparate length and time scales over which physical processes interact. Implicit solvers enable the physical system to be integrated with a time step commensurate with processes being studied. The dominant cost of an implicit time step is the ancillary linear system solves, so we have developed a preconditioner aimed at improving the efficiency of these linear system solves. Our preconditioner is based on an approximate block factorization of the linearized shallow-water equations and has been implemented within the spectral element dynamical core within the Community Atmospheric Model (CAM-SE). In this paper we discuss the development and scalability of the preconditioner for a suite of test cases with the implicit shallow-water solver within CAM-SE.

  14. Ann bay lodyans 7 / se Bryant Freeman ("Tonton Liben") ki pare ti liv sa a

    E-Print Network [OSTI]

    Freeman, Bryant C.

    2000-01-01

    la. Ti nonm Ian pa souke ko I tou. Wa a mete de men nan tet pou I rele. Konsa Wa a fe yo pran Malis, yo mete I nan yon sak, yo pandye I nan yon pyebwa annatandan yo voye I nan lanme. Malis t ap kalkile kisa pou I ta fe pou I chape, le de vole...." De vole yo tire oso, e se vole ki pi malen an ki antre nan sak la. Se konsa Malis rive chape anko. Sa gen kek jou depi yo te voye sak la nan lanme. Wa a t ap fe yon pwomnad, li pase devan kay Malis. Le I voye je I nan lakou a, sezisman manke touye...

  15. Yrast studies of {sup 80,82}Se using deep-inelastic reactions

    SciTech Connect (OSTI)

    Jones, G. A.; Regan, P. H.; Podolyak, Zs.; Gelletly, W.; Langdown, S. D. [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Yoshinaga, N. [Department of Physics, Saitama University, Saitama City 338-8570 (Japan); Higashiyama, K. [Department of Physics, Chiba Institute of Technology, Narashino, Chiba 275-0023 (Japan); De Angelis, G.; Gadea, A.; Axiotis, M.; Kroell, Th.; Marginean, N.; Martinez, T.; Napoli, D. R.; Tonev, D. [Istituto Nazionale di Fisica Nucleare (INFN), Laboratori Nazionali di Legnaro (Italy); Zhang, Y. H. [Institute of Modern Physics, CAS, Lanzhou (China); Ur, C. A.; Bazzacco, D.; Farnea, E.; Lenzi, S. [INFN Sezione di Padova (Italy)] (and others)

    2007-11-15

    We report the results of an experiment in which we studied the near-yrast states in selenium isotopes approaching N=50 following their population in multinucleon transfer reactions between a {sup 82}Se beam and a {sup 192}Os target. The level schemes for {sup 80,82}Se derived from the current work are compared with restricted-basis shell-model calculations and pair-truncated shell-model calculations. These provide a good description of the yrast sequences in these nuclei using a basis space limited to excitations in the {nu}(p{sub (3/2)},p{sub (1/2)},g{sub (9/2)}) and {pi}(f{sub (5/2)},p{sub (3/2)},p{sub (1/2)}) orbitals.

  16. CdS/PbSe heterojunction for high temperature mid-infrared photovoltaic detector applications

    SciTech Connect (OSTI)

    Weng, Binbin, E-mail: binbinweng@ou.edu, E-mail: shi@ou.edu; Qiu, Jijun; Zhao, Lihua; Chang, Caleb [The School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019 (United States); Shi, Zhisheng, E-mail: binbinweng@ou.edu, E-mail: shi@ou.edu [The School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019 (United States); Nanolight, Inc., Norman, Oklahoma 73069 (United States)

    2014-03-24

    n-CdS/p-PbSe heterojunction is investigated. A thin CdS film is deposited by chemical bath deposition on top of epitaxial PbSe film by molecular beam epitaxy on Silicon. Current-voltage measurements demonstrate very good junction characteristics with rectifying ratio of ?178 and ideality factor of 1.79 at 300?K. Detectors made with such structure exhibit mid-infrared spectral photoresponse at room temperature. The peak responsivity R{sub ?} and specific detectivity D{sup *} are 0.055?A/W and 5.482?×?10{sup 8}?cm·Hz{sup 1/2}/W at ??=?4.7??m under zero-bias photovoltaic mode. Temperature-dependent photoresponse measurements show abnormal intensity variation below ?200?K. Possible reasons for this phenomenon are also discussed.

  17. Magnetism in La?O?(Fe??xMnx)?Se? tuned by Fe/Mn ratio

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

    Lei, Hechang; Bozin, Emil S.; Llobet, A.; Ivanovski, V.; Koteski, V.; Belosevic-Cavor, J.; Cekic, B.; Petrovic, C.

    2012-09-01

    We report the evolution of structural and magnetic properties in La?O?(Fe??xMnx)?Se?. Heat capacity and bulk magnetization indicate an increased ferromagnetic component of the long-range magnetic order and possible increased degree of frustration. Atomic disorder on Fe(Mn) sites suppresses the temperature of the long-range order whereas intermediate alloys show a rich magnetic phase diagram.

  18. Statistical Mechanics of Disordered Systems, SoSe 2005 Timo Aspelmeier, Alexander K. Hartmann, Universitat Gottingen

    E-Print Network [OSTI]

    Hartmann, Alexander K.

    Statistical Mechanics of Disordered Systems, SoSe 2005 Timo Aspelmeier, Alexander K. Hartmann reserach! Statistics: most people leave our offices alive. Homepage: http://www.theorie.physik.uni-goe.de/~hartmann://www.theorie.physik.uni-goe.de/~aspel Alexander K. Hartmann Office A4.108 Phone +49-(0)551 39 5995 hartmann@physik.uni-goettingen.de http://www.theorie.physik.uni-goe.de/~hartmann

  19. Multinucleon Transfer Reactions to Study Single-Particle Evolution in Se Isotopes

    SciTech Connect (OSTI)

    Regan, P. H.; Jones, G. A.; Podolyak, Zs.; Gelletly, W.; Langdown, S. D. [Dept. of Physics, School of Electronics and Physical Sciences, Guildford, Surrey, UK (United Kingdom); Yoshinaga, N. [Department of Physics, Saitama University, Saitama City, 338-8570 (Japan); Higashiyama, K. [Department of Physics, University of Tokyo, Hongo, Tokyo, 113-0033 (Japan); De Angelis, G.; Gadea, A.; Axiotis, M.; Kroell, Th.; Marginean, N.; Martinez, T.; Napoli, D. R.; Rusu, C.; Tonev, D. [INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Zhang, Y. H. [INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Institute of Modern Physics, CAS, Lanzhou (China); Ur, C. A.; Bazzacco, D.; Farnea, E. [INFN, Sezione di Padova, Padova (Italy)] (and others)

    2006-03-13

    This contribution reports on the results of an experiment to study the near-yrast states in selenium isotopes around N=50, following their population in thick-target, multinucleon transfer reactions between an 82Se beam and a 192Os target. Discrete decays from states with spins of 20({Dirac_h}/2{pi}) and higher are clearly identified in the Os-like fragments. Information on the size of the energy gap between the f5/2 and p3/2 proton orbitals can be inferred from the spectroscopy of the N=48 isotone, 82Se. The experiment results for the level schemes for 80,82Se derived in the current work are compared with restricted-basis shell model calculations, which give a good description of the yrast sequences of these nuclei using a basis space limited to excitations in the (p3/2, p1/2, g9/2) neutron and (f5/2, p3/2, p1/2 ) proton orbitals.

  20. 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 3–4.5 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.

  1. X-ray irradiation induced changes in electron transport in stabilized a-Se photoconductors

    SciTech Connect (OSTI)

    Walornyj, M.; Kasap, S. O.

    2013-12-07

    We have examined the effect of high-dose x-ray irradiation on electron transport in stabilized amorphous selenium (a-Se) x-ray photoconductive films (of the type used in x-ray image detectors) by measuring the electron lifetime ?{sub e} through interrupted-field time-of-flight experiments. X-ray induced effects have been examined through two types of experiments. In recovery experiments, the a-Se was preirradiated with and without an applied field (5 V/?m) during irradiation with sufficient dose (typically ?20 Gy at 21 °C) to significantly reduce the electron lifetime by ?50%, and then the recovery of the lifetime was monitored as a function of time at three different temperatures, 10 °C, 21 °C, and 35 °C. The lifetime recovery kinetics was exponential with a relaxation time ?{sub r} that is thermally activated with an activation energy of 1.66 eV. ?{sub r} is a few hours at 21 °C and only a few minutes at 35 °C. In experiments examining the irradiation induced effects, the a-Se film was repeatedly exposed to x-ray radiation and the changes in the drift mobility and lifetime were monitored as a function of accumulated dose D. There was no observable change in the drift mobility. At 21 °C, the concentration of x-ray induced deep traps (or capture centers), N{sub d}, increases linearly with D (N{sub d} ? D) whereas at 35 °C, the recovery process prevents a linear increase in N{sub d} with D, and N{sub d} saturates. In all cases, even under high dose irradiation (?50 Gy), the lifetime was recoverable to its original equilibrium (pre-exposure) value within a few relaxation times.

  2. The thermally stimulated conductivity in amorphous thin film As?Se

    E-Print Network [OSTI]

    Bryant, John Duffie

    1972-01-01

    V with a 14 -3 density of 9. 73 x 10 cm . The thermal velocity of the carriers 6 -18 was 6. 34 x 10 cm/sec, and the capture cross section was 2. 7 x 10 2 cm . These results indicate that the Nett-Davis model is more ap- plicable to amorphous As Se... II-3 Sample Holder Design (not to scale) 15 16 17 11-4 Output Curve for Chromel-Constantan Thermo- couple (Voltage vs. Temperature) (ref. 29) 19 II-5 System Cooling Curve (Temperature vs. Time) 20 II-6 System Heating Curve for a Constant Heater...

  3. Structural and optical studies on AgSbSe{sub 2} thin films

    SciTech Connect (OSTI)

    Asokan, T. Namitha; Urmila, K. S.; Pradeep, B. [Solid State Physics Laboratory, Department of Physics, Cochin University of Science and Technology, Kochi- 22, Kerala (India)

    2014-01-28

    AgSbSe{sub 2} semiconducting thin films are successfully deposited using reactive evaporation technique at a substrate temperature of 398K. X-ray diffraction studies reveal that the films are polycrystalline in nature. The structural parameters such as average particle size, dislocation density, and number of crystallites per unit have been evaluated. Atomic Force Microscopy is used to study the topographic characteristics of the film including the grain size and surface roughness. The silver antimony selenide thin films have high absorption coefficient of about 10{sup 5} cm{sup ?1} and it has an indirect band gap of 0.64eV.

  4. Ann bay lodyans 10 / Se Bryant Freeman ("Tonton Liben") ki pare ti liv sa a

    E-Print Network [OSTI]

    Freeman, Bryant C.

    2000-01-01

    KU ScholarWorks | http://kuscholarworks.ku.edu Ann Bay Lodyans 10 se Bryant Freeman (“Tonton Liben”) ki pare ti liv sa a 2000 by Bryant C. Freeman, ed. This work has been made available by the University of Kansas Libraries’ Office of Scholarly... Freeman (“Tonton Liben”) ki pare ti liv sa a. [Lawrence, Kan.] : Institute of Haitian Studies ; [Port-au-Prince] : Bon Nouvèl : Fondasyon Alfa Lwès, 2000. Terms of Use: http://www2.ku.edu/~scholar/docs/license.shtml Tl CHENN LO A Te gen yon nonm ki te...

  5. Ann bay lodyans 12 / Se Bryant Freeman ("Tonton Liben") ki pare ti liv sa a

    E-Print Network [OSTI]

    Freeman, Bryant C.

    2000-01-01

    KU ScholarWorks | http://kuscholarworks.ku.edu Ann Bay Lodyans 12 se Bryant Freeman (“Tonton Liben”) ki pare ti liv sa a 2000 by Bryant C. Freeman, ed. This work has been made available by the University of Kansas Libraries’ Office of Scholarly... Freeman (“Tonton Liben”) ki pare ti liv sa a. [Lawrence, Kan.] : Institute of Haitian Studies ; [Port-au-Prince] : Bon Nouvèl : Fondasyon Alfa Lwès, 2000. Terms of Use: http://www2.ku.edu/~scholar/docs/license.shtml EPI BONDYE KREYE PREMYE FS A Nan...

  6. Determination of the Exciton Binding Energy in CdSe Quantum Dots

    SciTech Connect (OSTI)

    Meulenberg, R; Lee, J; Wolcott, A; Zhang, J; Terminello, L; van Buuren, T

    2009-10-27

    The exciton binding energy (EBE) in CdSe quantum dots (QDs) has been determined using x-ray spectroscopy. Using x-ray absorption and photoemission spectroscopy, the conduction band (CB) and valence band (VB) edge shifts as a function of particle size have been determined and combined to obtain the true band gap of the QDs (i.e. without and exciton). These values can be compared to the excitonic gap obtained using optical spectroscopy to determine the EBE. The experimental EBE results are compared with theoretical calculations on the EBE and show excellent agreement.

  7. ScanningTunneling Luminescence of Grain Boundaries in Cu(In,Ga)Se2

    SciTech Connect (OSTI)

    Romero, M. J.; Jiang, C.-S.; Al-Jassim, M. M.; Noufi, R.

    2005-01-01

    At the Laboratory, photon emission in semiconductors has been mapped in the nanoscale using scanning tunneling microscopy (STM). In this Solar Program Review Meeting, we report on the latest results obtained in Cu(In,Ga)Se2 (CIGS) thin films by this adapted STM. Scanning tunneling luminescence (STL) spectroscopy suggests that photons are emitted near the surface of CIGS. STL is excited either by (1) diffusion of tunneling electrons and subsequent recombination with available holes in CIGS or (2) impact ionization by hot electrons. Which process becomes predominant depends on the voltage applied to the STM tip. Photon mapping shows electronically active, extended defects near the surface of CIGS thin films.

  8. Ann bay lodyans 9 / se Bryant Freeman ("Tonton Liben") ki pare ti liv sa a

    E-Print Network [OSTI]

    Freeman, Bryant C.

    2000-01-01

    Liben”) ki pare ti liv sa a. [Lawrence, Kan.] : Institute of Haitian Studies ; [Port-au-Prince] : Bon Nouvèl : Fondasyon Alfa Lwès, 2000. Terms of Use: http://www2.ku.edu/~scholar/docs/license.shtml MARYAJ MALIS TWOUKOUKOU Vwala se Malis ki gen yon sel... rantre nan chanm Ian ak yon lanp. Yo gade, epi yo we moun ak mouchwa wouj la. Yo peze kou moun ak foula a jous li toufe, epi yo ale. Nan denmen maten, Malis leve. L al di yo: "Mezanmi, mesi anpil. M gen lontan m pa gen yon bon nwit kon sa...

  9. Ann bay lodyans 8 / se Bryant Freeman ("Tonton Liben") ki pare ti liv sa a

    E-Print Network [OSTI]

    Freeman, Bryant C.

    2000-01-01

    Liben”) ki pare ti liv sa a. [Lawrence, Kan.] : Institute of Haitian Studies ; [Port-au-Prince] : Bon Nouvèl : Fondasyon Alfa Lwès, 2000. Terms of Use: http://www2.ku.edu/~scholar/docs/license.shtml YON TOTI K AP CHANTE Vwala te gen yon neg yo rele... Gwoje. Msye te konn plante diri. Chak ane li pa janm ka fe bon rekot. Bet yo pran tout plezi yo nan manje jaden diri a. Se konsa, Gwoje blije mete veye pou trape vole k ap depafini jaden I la. Yon jou, pandan Pijon ak Kanna ap soti pou al nan jaden...

  10. Neutron Scattering Study on spin dynamics in superconducting (TlRb)2Fe4Se5

    SciTech Connect (OSTI)

    Chi, Songxue [ORNL; Ye, Feng [ORNL; Bao, Wei [Renmin University of China; Fang, Dr. Minghu [Zhejiang University; Wang, H.D. [Zhejiang University; Dong, C.H. [Zhejiang University; Savici, Andrei T [ORNL; Granroth, Garrett E [ORNL; Stone, Matthew B [ORNL; Fishman, Randy Scott [ORNL

    2013-01-01

    Spin dynamics in superconducting (Tl,Rb)2Fe4Se5 was investigated using the inelastic neutron scattering technique. Spin wave branches that span an energy range from 6.5 to 209 meV are success- fully described by a Heisenberg model whose dominant interactions include only the in-plane nearest (J1 and J0 1) and next nearest neighbor (J2 and J0 2) exchange terms within and between the tetramer spin blocks, respectively. These exchange constants, experimentally determined in this work, would crucially constrain the diverse theoretical viewpoints on magnetism and superconductivity in the Fe-based materials.

  11. Giant increase in critical current density of KxFe2-ySe? single crystals

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

    Lei, Hechang; Petrovic, C.

    2011-12-28

    The critical current density Jabc of KxFe2-ySe? single crystals can be enhanced by more than one order of magnitude, up to ~2.1×10? A/cm² by the post annealing and quenching technique. A scaling analysis reveals the universal behavior of the normalized pinning force as a function of the reduced field for all temperatures, indicating the presence of a single vortex pinning mechanism. The main pinning sources are three-dimensional (3D) point-like normal cores. The dominant vortex interaction with pinning centers is via spatial variations in critical temperature Tc (“?Tc pinning”).

  12. Flow of US/SE Program Funding to National Laboratories (FY 2014 Enacted) |

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirleyEnergy A plug-inPPLforLDRD Report toDepartment of Energy Figure 4.2: Flow of US/SE

  13. DISSERTATION IMPACT OF SECONDARY BARRIERS ON CuIn1-xGaxSe2 SOLAR-CELL

    E-Print Network [OSTI]

    Sites, James R.

    , it is important that red-light J-V of CIS solar cells be distortion-free. It was shown that one approach to reduceDISSERTATION IMPACT OF SECONDARY BARRIERS ON CuIn1-xGaxSe2 SOLAR-CELL OPERATION Submitted by Alexei Impact of Secondary Barriers on CuIn1-xGaxSe2 Solar-Cell Operation Thin-film solar cells based on CuInSe2

  14. Dependence of superconductivity in CuxBi?Se? on quenching conditions

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

    Schneeloch, J. A.; Zhong, R. D.; Xu, Z. J.; Gu, G. D.; Tranquada, J. M.

    2015-04-20

    Topological superconductivity, implying gapless protected surface states, has recently been proposed to exist in the compound CuxBi?Se?. Unfortunately, low diamagnetic shielding fractions and considerable inhomogeneity have been reported in this compound. In an attempt to understand and improve on the finite superconducting volume fractions, we have investigated the effects of various growth and post-annealing conditions. With a melt-growth (MG) method, diamagnetic shielding fractions of up to 56% in Cu???Bi?Se? have been obtained, the highest value reported for this method. We investigate the efficacy of various quenching and annealing conditions, finding that quenching from temperatures above 560°C is essential for superconductivity,more »whereas quenching from lower temperatures or not quenching at all is detrimental. A modified floating zone (FZ) method yielded large single crystals but little superconductivity. Even after annealing and quenching, FZ-grown samples had much less chance of being superconducting than MG-grown samples. From the low shielding fractions in FZ-grown samples and the quenching dependence, we suggest that a metastable secondary phase having a small volume fraction in most of the samples may be responsible for the superconductivity.« less

  15. Tensile Strain Switched Ferromagnetism in Layered NbS2 and NbSe2

    SciTech Connect (OSTI)

    Zhou, Yungang; Wang, Zhiguo; Yang, Ping; Zu, Xiaotao; Yang, Li; Sun, Xin; Gao, Fei

    2012-11-01

    Developing approaches to effectively induce and control the magnetic states is critical to the use of magnetic nanostructures in quantum information devices but is still challenging. Here we have demonstrated, by employing the density functional theory calculations, an existence of infinite magnetic sheets with structural integrity and magnetic homogeneity. Examination from a series of transition metal dichalcogenides shows that the biaxial tensile strained NbS2 and NbSe2 structures can be magnetized with a ferromagnetic character due to the competitive effects of through-bond interaction and through-space interaction. The estimated Curie temperatures (387 and 542 K under the 10% strain for NbS2 and NbSe2 structures, respectively) suggest that the unique ferromagnetic character can be achieved above room temperature. The self-exchange of population between 4d orbitals of Nb atom that leads to the exchange splitting is the mechanism behind the transition of the spin moment. The induced magnetic moments can be significantly enhanced by the tensile strain, even giving rise to half-metallic character with the strong spin polarization around the Fermi level. Given the recent progress that the desired strain can be achieved on two-dimensional nanostructures, such as graphene and BN layer in a controlled way, we believe that our calculated results are suitable for experimental verification and implementation opening a new path to explore the spintronics in pristine two-dimensional nanostructures.

  16. Dependence of superconductivity in CuxBi2Se3 on quenching conditions

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

    Schneeloch, J. A.; Zhong, R. D.; Xu, Z. J.; Gu, G. D.; Tranquada, J. M.

    2015-04-20

    Topological superconductivity, implying gapless protected surface states, has recently been proposed to exist in the compound CuxBi?Se?. Unfortunately, low diamagnetic shielding fractions and considerable inhomogeneity have been reported in this compound. In an attempt to understand and improve on the finite superconducting volume fractions, we have investigated the effects of various growth and post-annealing conditions. With a melt-growth (MG) method, diamagnetic shielding fractions of up to 56% in Cu???Bi?Se? have been obtained, the highest value reported for this method. We investigate the efficacy of various quenching and annealing conditions, finding that quenching from temperatures above 560°C is essential for superconductivity,more »whereas quenching from lower temperatures or not quenching at all is detrimental. A modified floating zone (FZ) method yielded large single crystals but little superconductivity. Even after annealing and quenching, FZ-grown samples had much less chance of being superconducting than MG-grown samples. Thus, from the low shielding fractions in FZ-grown samples and the quenching dependence, we suggest that a metastable secondary phase having a small volume fraction in most of the samples may be responsible for the superconductivity.« less

  17. Polytypism, polymorphism, and superconductivity in TaSe2-xTex

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

    Luo, Huixia; Tao, Jing; Xie, Weiwei; Inoue, Hiroyuki; Gyenis, Andras; Krizan, Jason W.; Yazdani, Ali; Zhu, Yimei; Cava, R. J.

    2015-03-17

    Polymorphism in materials often leads to significantly different physical properties - the rutile and anatase polymorphs of TiO? are a prime example. Polytypism is a special type of polymorphism, occurring in layered materials when the geometry of a repeating structural layer is maintained but the layer stacking sequence of the overall crystal structure can be varied; SiC is an example of a material with many polytypes. Although polymorphs can have radically different physical properties, it is much rarer for polytypism to impact physical properties in a dramatic fashion. Here we study the effects of polytypism and polymorphism on the superconductivitymore »of TaSe?, one of the archetypal members of the large family of layered dichalcogenides. We show that it is possible to access 2 stable polytypes and 2 stable polymorphs in the TaSe2-xTex solid solution, and find that the 3R polytype shows a superconducting transition temperature that is between 6 and 17 times higher than that of the much more commonly found 2H polytype. The reason for this dramatic change is not apparent, but we propose that it arises either from a remarkable dependence of Tc on subtle differences in the characteristics of the single layers present, or from a surprising effect of the layer stacking sequence on electronic properties that instead are expected to be dominated by the properties of a single layer in materials of this kind.« less

  18. First observation of temperature dependent lightinduced response of Ge25As10Se65 thin films

    E-Print Network [OSTI]

    Khan, Pritam; Deshpande, Uday; Adarsh, K V

    2015-01-01

    Ge rich ternary chalcogenide glasses (ChG) exhibit photobleaching (PB) when illuminated with bandgap light and such an effect is originating from the combined effect of intrinsic structural changes and photo-oxidation. In a sharp contradict to these previous observations, in this letter, we demonstrate for the first time that Ge rich Ge25As10Se65 ChG thin films exhibit photodarkening (PD) at 20 K and PB at 300 and 420 K for continuous illumination of ~ 3 hours. Strikingly, the temporal evolution of PD/PB show distinct characteristics at the temperatures of illumination and provide valuable information on the light induced structural changes. Further, structure specific far infrared (FIR) absorption measurements give direct evidence of different structural units involved in PD/PB at the contrasting temperatures. By comparing the lightinduced effects in vacuum and air, we conclude that intrinsic structural changes dominate over photo-oxidation in the observed PB in Ge25As10Se65 ChG thin films.

  19. Polytypism, polymorphism, and superconductivity in TaSe2–xTex

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

    Luo, Huixia; Xie, Weiwei; Tao, Jing; Inoue, Hiroyuki; Gyenis, András; Krizan, Jason W.; Yazdani, Ali; Zhu, Yimei; Cava, Robert Joseph

    2015-03-03

    Polymorphism in materials often leads to significantly different physical properties - the rutile and anatase polymorphs of TiO? are a prime example. Polytypism is a special type of polymorphism, occurring in layered materials when the geometry of a repeating structural layer is maintained but the layer stacking sequence of the overall crystal structure can be varied; SiC is an example of a material with many polytypes. Although polymorphs can have radically different physical properties, it is much rarer for polytypism to impact physical properties in a dramatic fashion. Here we study the effects of polytypism and polymorphism on the superconductivitymore »of TaSe?, one of the archetypal members of the large family of layered dichalcogenides. We show that it is possible to access 2 stable polytypes and 2 stable polymorphs in the TaSe2-xTex solid solution, and find that the 3R polytype shows a superconducting transition temperature that is between 6 and 17 times higher than that of the much more commonly found 2H polytype. Thus, the reason for this dramatic change is not apparent, but we propose that it arises either from a remarkable dependence of Tc on subtle differences in the characteristics of the single layers present, or from a surprising effect of the layer stacking sequence on electronic properties that instead are expected to be dominated by the properties of a single layer in materials of this kind.« less

  20. The role of ligands in the optical and electronic spectra of CdSe nanoclusters

    SciTech Connect (OSTI)

    Kilina, Svletana; Sergei, Ivanov A; Victor, Klimov I; Sergei, Tretiak

    2008-01-01

    We investigate the impact of ligands on morphology, electronic structure, and optical response of the Cd33Se33 cluster, which already overlapps in size with the smallest synthesized CdSe quantum dots (QDs). Our Density Functional Theory (DFT) calculations demonstrate significant surface reorganization both for the bare cluster and for the cluster capped by amine and phosphine oxide ligand models. We observe strong surface-ligand interactions leading to substantial charge redistribution and polarization effects on the surface. This effect results in the appearance of hybridized states, where the electronic density is spread over the cluster and the ligands. Neither the ligand's nor hybridized molecular orbitals appear as trap states inside or near the band gap of the QD. Instead, being optically dark, dense hybridized states from the edges of the valence and the conduction bands could open new relaxation channels for high energy photoexcitations. Comparing quantum dots passivated by different ligands, we found that hybridized states are denser in at the edge of the conduction band of the cluster ligated with phosphine oxide molecules than that with primary amines. Such a different manifestation of ligand binding may potentially lead to the faster electron relaxation in dots passivated by phosphine oxide than by amine ligands, which is in agreement with experimental data.

  1. Electronic Structure of Ligated CdSe Clusters: Dependence on DFT Methodology

    SciTech Connect (OSTI)

    Albert, VV; Ivanov, SA; Tretiak, S; Kilina, SV

    2011-07-07

    Simulations of ligated semiconductor quantum dots (QDs) and their physical properties, such as morphologies, QD-ligand interactions, electronic structures, and optical transitions, are expected to be very sensitive to computational methodology. We utilize Density Functional Theory (DFT) and systematically study how the choice of density functional, atom-localized basis set, and a solvent affects the physical properties of the Cd{sub 33}Se{sub 33} cluster ligated with a trimethyl phosphine oxide ligand. We have found that qualitative performance of all exchange-correlation (XC) functionals is relatively similar in predicting strong QD-ligand binding energy ({approx}1 eV). Additionally, all functionals predict shorter Cd-Se bond lengths on the QD surface than in its core, revealing the nature and degree of QD surface reconstruction. For proper modeling of geometries and QD-ligand interactions, however, augmentation of even a moderately sized basis set with polarization functions (e.g., LANL2DZ* and 6-31G*) is very important. A polar solvent has very significant implications for the ligand binding energy, decreasing it to 0.2-0.5 eV. However, the solvent model has a minor effect on the optoelectronic properties, resulting in persistent blue shifts up to {approx}0.3 eV of the low-energy optical transitions. For obtaining reasonable energy gaps and optical transition energies, hybrid XC functionals augmented by a long-range Hartree-Fock orbital exchange have to be applied.

  2. Effect of Ligands on Characteristics of (CdSe)13 Quantum Dot

    SciTech Connect (OSTI)

    Gao, Yang; Zhou, Bo; Kang, Seung-gu; Xin, Minsi; Yang, Ping; Dai, Xing; Wang, Zhigang; Zhou, Ruhong

    2014-01-01

    The widespread applications of quantum dots (QDs) have spurred an increasing interest in the study of their coating ligands, which can not only protect the electronic structures of the central QDs, but also control their permeability through biological membranes with both size and shape. In this work, we have used density functional theory (DFT) to investigate the electronic structures of (CdSe)13 passivated by OPMe2(CH2)nMe ligands with different lengths and various numbers of branches (Me=methyl group, n = 0, 1-3). Our results show that the absorption peak in the ultraviolet-visible (UV-vis) spectra displays a clear blue-shift, on the scale of ~100 nm, upon the binding of ligands. Once the total number of ligands bound with (CdSe)13 reached a saturated number (9 or 10), no more blue-shift occurred in the absorption peak in the UV-vis spectra. On the other hand, the aliphatic chain length of ligands has a negligible effect on the optical properties of the QD core. Analyses of the bonding characteristics confirm that optical transitions are dominantly governed by the central QD core rather than the organic passivation. Interestingly, the density of states (DOS) share similar characteristics as vibrational spectra, even though there is no coordination vibration mode between the ligands and the central QD. These findings might provide insights on the material design for the passivation of quantum dots for biomedical applications.

  3. Postal address School of Industrial Design, LTH, P.O. Box 118, 221 00 Lund, SWEDEN Telephone +46 46 222 71 88 E-mail Lynn.Lindegren@kansli.lth.se Website www.industrialdesign.lth.se

    E-Print Network [OSTI]

    Postal address School of Industrial Design, LTH, P.O. Box 118, 221 00 Lund, SWEDEN Telephone +46 46 222 71 88 E-mail Lynn.Lindegren@kansli.lth.se Website www.industrialdesign.lth.se School of Industrial of Industrial Design autumn semester 2015. Full-time study is 30 credits. Bachelor´s programme ­ 1st term Course

  4. Flowing versus Static Conditions for Measuring Multiple Exciton Generation in PbSe Quantum Dots

    SciTech Connect (OSTI)

    Midgett, Aaron G. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Univ. of Colorado, Boulder, CO (United States); Hillhouse, Hugh W. [Univ. of Washington, Seattle, WA (United States); Hughes, Barbara K. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Univ. of Colorado, Boulder, CO (United States); Nozik, Arthur J. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Univ. of Colorado, Boulder, CO (United States); Beard, Matthew C. [Univ. of Colorado, Boulder, CO (United States)

    2010-09-22

    Recent reports question the validity of pulsed fs-laser experiments for measuring the photon-to-exciton quantum yields (QYs) that result from multiple exciton generation (MEG). The repetitive nature of these experiments opens up an alternative relaxation pathway that may produce artificially high results. We present transient-absorption (TA) data for 4.6 and 6.6 nm diameter PbSe quantum dots (QDs) at a variety of pump photon energies. The data are collected under laminar flow conditions with volumetric flow rates ranging from 0 to 150 mL/min (resulting in Reynolds numbers up to 460). The results are modeled with a spatially resolved population balance of generation, recombination, convective replacement, and accumulation of long-lived excited QDs. By comparing the simulations and experiments, the steady-state population of the long-lived QD-excited states and their kinetics are determined for different experimental conditions. We also improve upon reported photon-to-exciton QYs for PbSe QDs. We find differences in the observed TA dynamics between flowing and static conditions that depend upon photon fluence, pump photon energy, and quality of the QD surfaces. For excitation energies below 2 Eg, independent of QD size or photon fluence, we observe no flow rate dependence in the TA dynamics. At excitation energies of h? > 3 Eg, we observe differences between static and flowing conditions that are most pronounced for high photon fluences. At 3.7 Eg and for 4.6 nm PbSe QDs we find a QY of 1.2 ± 0.1 and at 4.5 Eg the QY is 1.55 ± 0.05. With 6.6 nm QDs excited at 4.7 Eg we observe no difference between static and flowing conditions and find a QY of 1.61 ± 0.05. We also find that by treating the surface of QDs, we can decrease the charging probability (Pg ? 5 × 10-5) by a factor of 3-4. The observed variations suggest that different QD samples vary regarding their susceptibility to the creation of long-lived states.

  5. Conduction in Charged PbSe Nanocrystal Films Brian L. Wehrenberg, Dong Yu, Jiasen Ma, and Philippe Guyot-Sionnest*

    E-Print Network [OSTI]

    Yu, Dong

    system for incorporation into solar cells and photodetectors.7-9 The ability to successfully properties of arrays of semiconductor nano- crystals have been studied previously. Arrays of uncharged CdSe was seen to increase by several orders of magnitude.11 At low temperature, the conduction in these CdSe

  6. Crystalline ZnMgSe:Cr2+: a new material for active elements of tunable IR-lasers

    E-Print Network [OSTI]

    Yu. A. Zagoruiko; N. O. Kovalenko; O. A. Fedorenko; V. A. Khristyan

    2008-07-01

    Obtained is a new thermostable material for active elements of tunable IR-lasers - Zn1-xMgxSe:Cr2+ single crystals. The position of the absorption band of Cr2+ ions in wurtzite-type Zn0.8Mg0.2Se matrix is established.

  7. 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.

  8. Hole transport and doping states in epitaxial CuIn1 xGaxSe2 David J. Schroeder

    E-Print Network [OSTI]

    Rockett, Angus

    . They have been shown to yield solar cells with efficiencies greater than 17%, and over time films of group III-rich CuIn1 xGaxSe2 CIGS . The films were produced using a hybrid sputtering interest in renewable energy sources such as photovoltaic devices. CuIn1 xGaxSe2 CIGS /CdS hetero- junction

  9. Approved Module Information for SE4025, 2014/5 Module Title/Name: Further Topics in Engineering

    E-Print Network [OSTI]

    Neirotti, Juan Pablo

    Approved Module Information for SE4025, 2014/5 Module Title/Name: Further Topics in Engineering Management Module Code: SE4025 School: Engineering and Applied Science Module Type: Standard Module New Module? No Module Credits: 15 Module Management Information Module Leader Name Robin Clark Email Address

  10. Hydrogen passivation of Se and Te in AlSb M. D. McCluskey and E. E. Haller

    E-Print Network [OSTI]

    McCluskey, Matthew

    Hydrogen passivation of Se and Te in AlSb M. D. McCluskey and E. E. Haller Lawrence Berkeley observed local vibrational modes LVM's arising from DX-hydrogen complex in AlSb. Hydrogen was diffused into bulk AlSb:Se and AlSb:Te by annealing in sealed quartz ampoules with either hydrogen gas or methanol CH

  11. Highly efficient nonradiative energy transfer using charged CdSe/ZnS nanocrystals for light-harvesting in solution

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    % in solution. CdTe and CdSe/ZnS dots of different sizes have further been studied for energy trans- fer in filmHighly efficient nonradiative energy transfer using charged CdSe/ZnS nanocrystals for light-harvesting in solution Evren Mutlugün,a Sedat Nizamolu, and Hilmi Volkan Demirb Department of Physics; Department

  12. Device modeling and simulation of the performance of Cu(In1x,Gax)Se2 solar cells

    E-Print Network [OSTI]

    Anderson, Timothy J.

    -junction Cu(In1Àx,Gax)Se2 (CIGS) solar cells. Increasing the open-circuit voltage (Voc) to improve the overallDevice modeling and simulation of the performance of Cu(In1Àx,Gax)Se2 solar cells Jiyon Song solar cell have been carried out. A variety of graded band-gap structures, including space charge region

  13. Planar waveguide obtained by burying a Ge22As20Se58 fiber in As2S3 glass

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Planar waveguide obtained by burying a Ge22As20Se58 fiber in As2S3 glass Quentin Coulombier glasses. Two highly mature chalcogenide glasses are used for these experiments. GASIR glass from Umicore IR Glass, Olen, Belgium, with the composition of Ge22As20Se58 is used to draw fibers

  14. Atomic structures and electronic properties of 2H-NbSe{sub 2}: The impact of Ti doping

    SciTech Connect (OSTI)

    Li, Hongping, E-mail: hpli@mail.ujs.edu.cn, E-mail: zcwang@wpi-aimr.tohoku.ac.jp; Chen, Lin; Zhang, Kun; Liang, Jiaqing; Tang, Hua; Li, Changsheng [Institute for Advanced Materials, School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Liu, Xiaojuan; Meng, Jian [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Wang, Zhongchang, E-mail: hpli@mail.ujs.edu.cn, E-mail: zcwang@wpi-aimr.tohoku.ac.jp [Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2014-09-14

    Layered transition metal dichalcogenides have aroused renewed interest as electronic materials, yet their electronic performances could be modified by chemical doping. Here, we perform a systematic first-principles calculation to investigate the effect of Ti doping on atomic structure and electronic properties of the 2H-NbSe{sub 2}. We consider a total of three possible Ti-doping models and find that both the substitution and intercalated models are chemically preferred with the intercalation model being more favorable than the substitution one. Structural analyses reveal a slight lattice distortion triggered by Ti doping, but the original structure of 2H-NbSe{sub 2} is maintained. We also observe an expansion of c axis in the substituted model, which is attributed to the reduced van der Waals interaction arising from the increased Se-Se bond length. Our calculations also predict that the electron transport properties can be enhanced by the Ti doping, especially for the Ti-intercalated 2H-NbSe{sub 2}, which should be beneficial for the realization of superconductivity. Furthermore, the covalence element is found in the Ti-Se bonds, which is ascribed to the hybridization of Ti 3d and Se 4p orbitals. The findings indicate that doping of transition metals can be regarded as a useful way to tailor electronic states so as to improve electron transport properties of 2H-NbSe{sub 2}.

  15. 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.

  16. Stable N-CuInSe.sub.2 /iodide-iodine photoelectrochemical cell

    DOE Patents [OSTI]

    Cahen, David (Rehovot, IL); Chen, Yih W. (Lakewood, CO)

    1985-01-01

    In a photoelectrochemical solar cell, stable output and solar efficiency in excess of 10% are achieved with a photoanode of n-CuInSe.sub.2 electrode material and an iodine/iodide redox couple used in a liquid electrolyte. The photoanode is prepared by treating the electrode material by chemical etching, for example in Br.sub.2 /MeOH; heating the etched electrode material in air or oxygen; depositing a surface film coating of indium on the electrode material after the initial heating; and thereafter again heating the electrode material in air or oxygen to oxidize the indium. The electrolyte is treated by the addition of Cu.sup.+ or Cu.sup.2+ salts and In.sup.3+ salts.

  17. Co-Evaporated Cu2ZnSnSe4 Films and Devices

    SciTech Connect (OSTI)

    Repins, I.; Beall, C.; Vora, N.; DeHart, C.; Kuciauskas, D.; Dippo, P.; To, B.; Mann, J.; Hsu, W. C.; Goodrich, A.; Noufi, R.

    2012-06-01

    The use of vacuum co-evaporation to produce Cu2ZnSnSe4 photovoltaic devices with 9.15% total-area efficiency is described. These new results suggest that the early success of the atmospheric techniques for kesterite photovoltaics may be related to the ease with which one can control film composition and volatile phases, rather than a fundamental benefit of atmospheric conditions for film properties. The co-evaporation growth recipe is documented, as is the motivation for various features of the recipe. Characteristics of the resulting kesterite films and devices are shown in scanning electron micrographs, including photoluminescence, current-voltage, and quantum efficiency. Current-voltage curves demonstrate low series resistance without the light-dark cross-over seen in many devices in the literature. Band gap indicated by quantum efficiency and photoluminescence is roughly consistent with that expected from first principles calculation.

  18. One-volt p-InP/n-CdSe regenerative photoelectrochemical cell

    SciTech Connect (OSTI)

    Ang, P.G.P.; Sammells, A.F.

    1983-08-01

    Features and performance of a two-photoelectrode regenerative photoelectrochemical (PEC) cell that yielded a combined photovoltage of more than one volt are reported. The photoanode was n-CdSe, the photocathode was p-InP, and the electrolyte was aqueous sulfide/polysulfide. Details of the fabrication process are provided, including formation of an ohmic contact by sputter deposited gold and then electroplating the photocathode with Zn, followed by a final sputtered gold layer. Tests under 100 mW/sq cm illumination of the unoptimized regenerative cell produced an open circuit voltage of 1.15 V, a short circuit current of 24 mA/sq cm, a fill factor of 0.40, and an overall efficiency of 5.5 percent.

  19. Fluorescence modulation in single CdSe quantum dots by moderate applied electric fields

    SciTech Connect (OSTI)

    LeBlanc, Sharonda J. [Department of Physics and Optical Science, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, North Carolina 28223 (United States); Department of Mechanical Engineering and Engineering Science, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, North Carolina 28223 (United States); McClanahan, Mason R.; Moyer, Tully; Moyer, Patrick J. [Department of Physics and Optical Science, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, North Carolina 28223 (United States); Jones, Marcus [Department of Chemistry, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, North Carolina 28223 (United States)

    2014-01-21

    Single molecule time-resolved fluorescence spectroscopy of CdSe/ZnS core-shell quantum dots (QDs) under the influence of moderate applied electric fields reveals distributed emission from states which are neither fully on nor off and pronounced changes in the excited state decay. The data suggest that a 54?kV/cm applied electric field causes small perturbations to the QD surface charge distribution, effectively increasing the surface trapping probability and resulting in the appearance of gray states. We present simultaneous blinking and fluorescence decay results for two sets of QDs, with and without an applied electric field. Further kinetic modeling analysis suggests that a single trapped charged cannot be responsible for a blinking off event.

  20. 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.

  1. 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.

  2. Stable n-CuInSe/sub 2/iodide-iodine photoelectrochemical cell

    DOE Patents [OSTI]

    Cahen, D.; Chen, Y.W.

    1984-09-20

    In a photoelectrochemical solar cell, stable output and solar efficiency in excess of 10% are achieved with a photoanode of n-CuInSe/sub 2/ electrode material and an iodine/iodide redox couple used in a liquid electrolyte. The photoanode is prepared by treating the electrode material by chemical etching, for example in Br/sub 2//MeOH; heating the etched electrode material in air or oxygen; depositing a surface film coating of indium on the electrode material after the initial heating; and thereafter again heating the electrode material in air or oxygen to oxidize the indium. The electrolyte is treated by the addition of Cu/sup +/ or Cu/sup 2 +/ salts and in In/sup 3 +/ salts.

  3. Nuclear Structure Relevant to Neutrinoless Double Beta Decay: 76Ge and 76Se

    E-Print Network [OSTI]

    J. P. Schiffer; S. J. Freeman; J. A. Clark; C. Deibel; C. R. Fitzpatrick; S. Gros; A. Heinz; D. Hirata; C. L. Jiang; B. P. Kay; A. Parikh; P. D. Parker; K. E. Rehm; A. C. C. Villari; V. Werner; C. Wrede

    2007-10-03

    The possibility of observing neutrinoless double beta decay offers the opportunity of determining the neutrino mass IF the nuclear matrix element were known. Theoretical calculations are uncertain and measurements of the occupations of valence orbits by nucleons active in the decay can be important. The occupation of valence neutron orbits in the ground states of 76Ge and 76Se were determined by precisely measuring cross sections for both neutron-adding and removing transfer reactions. Our results indicate that the Fermi surface is much more diffuse than in theoretical (QRPA) calculations. We find that the populations of at least three orbits change significantly between these two ground states while in the calculations the changes are confined primarily to one orbit.

  4. Nuclear Structure Relevant to Neutrinoless Double {beta} Decay: {sup 76}Ge and {sup 76}Se

    SciTech Connect (OSTI)

    Schiffer, J. P.; Gros, S.; Jiang, C. L.; Rehm, K. E. [Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Freeman, S. J.; Fitzpatrick, C. R.; Kay, B. P. [University of Manchester, Manchester M13 9PL (United Kingdom); Clark, J. A.; Deibel, C.; Heinz, A.; Parikh, A.; Parker, P. D.; Werner, V.; Wrede, C. [Yale University, New Haven, Connecticut 06520 (United States); Hirata, D. [GANIL (IN2P3/CNRS -DSM/CEA), B.P. 55027 14076 Caen Cedex 5 (France); Dept. of Physics and Astronomy, Open University, Milton Keynes, MK7 6AA (United Kingdom); Villari, A. C. C. [GANIL (IN2P3/CNRS -DSM/CEA), B.P. 55027 14076 Caen Cedex 5 (France)

    2008-03-21

    The possibility of observing neutrinoless double {beta} decay offers the opportunity of determining the effective neutrino mass if the nuclear matrix element were known. Theoretical calculations are uncertain, and measurements of the occupations of valence orbits by nucleons active in the decay can be important. The occupation of valence neutron orbits in the ground states of {sup 76}Ge (a candidate for such decay) and {sup 76}Se (the daughter nucleus) were determined by precisely measuring cross sections for both neutron-adding and removing transfer reactions. Our results indicate that the Fermi surface is much more diffuse than in theoretical calculations. We find that the populations of at least three orbits change significantly between these two ground states while in the calculations, the changes are confined primarily to one orbit.

  5. 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.

  6. Green route synthesis of high quality CdSe quantum dots for applications in light emitting devices

    SciTech Connect (OSTI)

    Bera, Susnata, E-mail: susnata.bera@gmail.com [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India); Singh, Shashi B. [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India); Ray, S.K., E-mail: physkr@phy.iitkgp.ernet.in [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)

    2012-05-15

    Investigation was made on light emitting diodes fabricated using CdSe quantum dots. CdSe quantum dots were synthesized chemically using olive oil as the capping agent, instead of toxic phosphine. Room temperature photoluminescence investigation showed sharp 1st excitonic emission peak at 568 nm. Bi-layer organic/inorganic (P3HT/CdSe) hybrid light emitting devices were fabricated by solution process. The electroluminescence study showed low turn on voltage ({approx}2.2 V) .The EL peak intensity was found to increase by increasing the operating current. - Graphical abstract: Light emitting diode was fabricated using CdSe quantum dots using olive oil as the capping agent, instead of toxic phosphine. Bi-layer organic/inorganic (P3HT/CdSe) hybrid light emitting device shows strong electroluminescence in the range 630-661 nm. Highlights: Black-Right-Pointing-Pointer CdSe Quantum dots were synthesized using olive oil as the capping agent. Black-Right-Pointing-Pointer Light emitting device was fabricated using CdSe QDs/P3HT polymer heterojunction. Black-Right-Pointing-Pointer The I-V characteristics study showed low turn on voltage at {approx}2.2 V. Black-Right-Pointing-Pointer The EL peak intensity increases with increasing the operating current.

  7. 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, E-mail: basudebk@cgcri.res.in [CSIR-Central Glass and Ceramic Research Institute, Glass Science and Technology Section, Glass Division, 196, Raja S. C. Mullick Road, 700032 Kolkata (India); Kr Mishra, Manish; De, Goutam [CSIR-Central Glass and Ceramic Research Institute, Nano-Structured Materials Division, 196, Raja S. C. Mullick Road, 700032 Kolkata (India); Goswami, Madhumita; Kothiyal, G. P. [Glass and Advanced Ceramics Division, Bhaba Atomic Research Centre, Trombay, 400085 Mumbai (India)

    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.

  8. Magnetic field induced third order susceptibility of third order harmonic generation in a ZnMgSe strained quantum well

    SciTech Connect (OSTI)

    Mark, J. Abraham Hudson, E-mail: a.john.peter@gmail.com; Peter, A. John, E-mail: a.john.peter@gmail.com [Dept. of Physics, SSM Institute of Engineering and Technology, Dindigul-624002 (India)

    2014-04-24

    Third order susceptibility of third order harmonic generation is investigated in a Zn{sub 0.1}Mg{sub 0.9}Se/Zn{sub 0.8}Mg{sub 0.2}Se/Zn{sub 0.1}Mg{sub 0.9}Se quantum well in the presence of magnetic field strength. The confinement potential is considered as the addition of energy offsets of the conduction band (or valence band) and the strain-induced potential in our calculations. The material dependent effective mass is followed throughout the computation because it has a high influence on the electron energy levels in low dimensional semiconductor systems.

  9. Effects of competing magnetic interactions on the electronic transport properties of CuCrSe{sub 2}

    SciTech Connect (OSTI)

    Tewari, Girish C.; Jawaharlal Nehru University, New Delhi 110067 ; Karppinen, Maarit; Rastogi, Ashok K.

    2013-02-15

    We have synthesized single-phase samples of the CuCrSe{sub 2} phase that exhibits hexagonal-rhombohedral layered crystal structure with space group R3m. Here we present a detailed study of electronic transport and magnetic properties of CuCrSe{sub 2}. We moreover investigate the heat capacity of CuCrSe{sub 2} in comparison to that of CuCrS{sub 2}. The electrical resistivity of CuCrSe{sub 2} shows metallic-like behavior down to 2 K, while the thermoelectric power is large around 100 {mu}V K{sup -1} at 300 K. A weak anomaly in resistivity and a rounded maximum in magnetic susceptibility are observed around 55 K. No sharp transition at 55 K is observed in the heat capacity of CuCrSe{sub 2}, rather a visible maximum is seen. At low temperatures from 2 to 14 K, the magnetic heat capacity follows T{sup 2}-dependence. We tentatively believe this behavior of CuCrSe{sub 2} to be due to competing magnetic interactions between intralayer Cr atoms. The ferromagnetic Cr-Se-Cr indirect exchange among intralayer Cr atoms is enhanced in the selenide compound (that is more metallic than the sulfide compound), and competes with the antiferromagnetic Cr-Cr direct interactions. The interlayer antiferromagnetic exchange through Cu atoms leads to magnetic ordering at low temperature at T{sub N}=55 K. - Graphical abstract: Comparison of magnetic properties of CuCrSe{sub 2} and CuCrS{sub 2} indicates a sharp cusp-like anomaly in magnetic susceptibility at the antiferromagnetic transition of CuCrS{sub 2} while the maximum of CuCrSe{sub 2} is well rounded. Magnetization is reversible after field-cooling (FC) and zero-field-cooling (ZFC) for both compounds. Highlights: Black-Right-Pointing-Pointer Layered CuCrSe{sub 2} can be synthesized in both fully and partially cation-ordered forms. Black-Right-Pointing-Pointer Contrary to previously believed insulating nature the cation-ordered phase is metallic. Black-Right-Pointing-Pointer Magnetic property of CuCrSe{sub 2} is somewhat different from that of CuCrS{sub 2}. Black-Right-Pointing-Pointer Magnetization and heat capacity data suggest complex short-range ordering for CuCrSe{sub 2}.

  10. 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.

  11. Photosensitivity of pulsed laser deposited Ge{sub 20}As{sub 20}Se{sub 60} and Ge{sub 10}As{sub 30}Se{sub 60} amorphous thin films

    SciTech Connect (OSTI)

    Hawlová, P.; Olivier, M.; Verger, F. [Department of Graphic Arts and Photophysics, Faculty of Chemical Technology, University of Pardubice, Studentská 573, 53210 Pardubice (Czech Republic); Nazabal, V. [Chemical Sciences Institute of Rennes (ISCR), Glasses and Ceramics Team, UMR-CNRS 6226, University of Rennes 1, 35042 Rennes Cedex (France); Department of Graphic Arts and Photophysics, Faculty of Chemical Technology, University of Pardubice, Studentská 573, 53210 Pardubice (Czech Republic); N?mec, P., E-mail: petr.nemec@upce.cz [Department of Graphic Arts and Photophysics, Faculty of Chemical Technology, University of Pardubice, Studentská 573, 53210 Pardubice (Czech Republic)

    2013-10-15

    Graphical abstract: - Highlights: • Amorphous Ge{sub 20}As{sub 20}Se{sub 60}/Ge{sub 10}As{sub 30}Se{sub 60} films are fabricated by pulsed laser deposition. • Photosensitivity of the layers is studied by employing spectroscopic ellipsometry. • As-deposited/relaxed thin films were irradiated by 593, 635, and 660 nm lasers. • Ge{sub 20}As{sub 20}Se{sub 60} layers present almost zero photorefraction in relaxed state. - Abstract: Amorphous Ge{sub 20}As{sub 20}Se{sub 60} and Ge{sub 10}As{sub 30}Se{sub 60} thin films are fabricated by pulsed laser deposition. Prepared films are characterized in terms of their morphology, chemical composition, and optical properties. Special attention is given to the photosensitivity of the layers, which was studied by spectroscopic ellipsometry with as-deposited, annealed and exposed films by three different laser sources (593, 635, and 660 nm). The results show better photostability for Ge{sub 20}As{sub 20}Se{sub 60} thin films, where photoinduced change of optical band gap was found to be equal or less than 0.04 eV and these layers present almost zero photorefraction.

  12. Processing approach towards the formation of thin-film Cu(In,Ga)Se2

    DOE Patents [OSTI]

    Beck, Markus E. (Falkensee, DE); Noufi, Rommel (Golden, CO)

    2003-01-01

    A two-stage method of producing thin-films of group IB-IIIA-VIA on a substrate for semiconductor device applications includes a first stage of depositing an amorphous group IB-IIIA-VIA precursor onto an unheated substrate, wherein the precursor contains all of the group IB and group IIIA constituents of the semiconductor thin-film to be produced in the stoichiometric amounts desired for the final product, and a second stage which involves subjecting the precursor to a short thermal treatment at 420.degree. C.-550.degree. C. in a vacuum or under an inert atmosphere to produce a single-phase, group IB-III-VIA film. Preferably the precursor also comprises the group VIA element in the stoichiometric amount desired for the final semiconductor thin-film. The group IB-IIIA-VIA semiconductor films may be, for example, Cu(In,Ga)(Se,S).sub.2 mixed-metal chalcogenides. The resultant supported group IB-IIIA-VIA semiconductor film is suitable for use in photovoltaic applications.

  13. Characterization of Cu(In,Ga)Se2 (CIGS) films with varying gallium ratios

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

    Claypoole, Jesse; Peace, Bernadette; Sun, Neville; Dwyer, Dan; Eisaman, Matthew D.; Haldar, Pradeep; Efstathiadis, Harry

    2015-09-05

    Cu(In1-x,Gax)Se2 (CIGS) absorber layers were deposited on molybdenum (Mo) coated soda-lime glass substrates with varying Ga content (described as Ga/(In+Ga) ratios) with respect to depth. As the responsible mechanisms for the limitation of the performance of the CIGS solar cells with high Ga contents are not well understood, the goal of this work was to investigate different properties of CIGS absorber films with Ga/(In+Ga) ratios varied between 0.29 and 0.41 (as determined by X-ray florescence spectroscopy (XRF)) in order to better understand the role that the Ga content has on film quality. The Ga grading in the CIGS layer hasmore »the effect causing a higher bandgap toward the surface and Mo contact while the band gap in the middle of the CIGS layer is lower. Also, a wider and larger Ga/(In+Ga) grading dip located deeper in the CIGS absorber layers tend to produce larger grains in the regions of the films that have lower Ga/(In+Ga) ratios. It was found that surface roughness decreases from 51.2 nm to 41.0 nm with increasing Ga/(In+Ga) ratios. However, the surface roughness generally decreases if the Ga grading occurs deeper in the absorber layer.« less

  14. The electric dipole response of $^{76}$Se above 4 MeV

    E-Print Network [OSTI]

    P. M. Goddard; N. Cooper; V. Werner; G. Rusev; P. D. Stevenson; A. Rios; C. Bernards; A. Chakraborty; B. P. Crider; J. H. Kelley; E. Kwan; J. Glorius; E. E. Peters; N. Pietralla; R. Raut; C. Romig; D. Savran; L. Schnorrenberger; M. K. Smith; K. Sonnabend; A. P. Tonchev; W. Tornow; S. W. Yates

    2013-06-17

    The dipole response of $^{76}_{34}$Se in the energy range 4 to 9 MeV has been analyzed using a $(\\vec\\gamma,{\\gamma}')$ polarized photon scattering technique, performed at the High Intensity $\\gamma$-Ray Source facility, to complement previous work performed using unpolarized photons. The results of this work offer both an enhanced sensitivity scan of the dipole response and an unambiguous determination of the parities of the observed J=1 states. The dipole response is found to be dominated by $E1$ excitations, and can reasonably be attributed to a pygmy dipole resonance. Evidence is presented to suggest that a significant amount of directly unobserved excitation strength is present in the region, due to unobserved branching transitions in the decays of resonantly excited states. The dipole response of the region is underestimated when considering only ground state decay branches. We investigate the electric dipole response theoretically, performing calculations in a 3D cartesian-basis time-dependent Skyrme-Hartree-Fock framework.

  15. Performance Characterization and Remedy of Experimental CuInGaSe2 Mini-Modules: Preprint

    SciTech Connect (OSTI)

    Pern, F. J.; Yan, F.; Mansfield, L.; Glynn, S.; Rekow, M.; Murion, R.

    2011-07-01

    We employed current-voltage (I-V), quantum efficiency (QE), photoluminescence (PL), electroluminescence (EL), lock-in thermography (LIT), and (electrochemical) impedance spectroscopy (ECIS) to complementarily characterize the performance and remedy for two pairs of experimental CuInGaSe2 (CIGS) mini-modules. One pair had the three scribe-lines (P1/P2/P3) done by a single pulse-programmable laser, and the other had the P2/P3 lines by mechanical scribe. Localized QE measurements for each cell strip on all four mini-modules showed non-uniform distributions that correlated well with the presence of performance-degrading strips or spots revealed by PL, EL, and LIT imaging. Performance of the all-laser-scribed mini-modules improved significantly by adding a thicker Al-doped ZnO layer and reworking the P3 line. The efficiency on one of the all-laser-scribed mini-modules increased notably from 7.80% to 8.56% after the performance-degrading spots on the side regions along the cell array were isolated by manual scribes.

  16. Temperature-driven band inversion in Pb?.??Sn?.??Se: Optical and Hall-effect studies

    SciTech Connect (OSTI)

    Anand, Naween; Gu, Genda; Buvaev, Sanal; Hebard, A. F.; Tanner, D. B.; Chen, Zhiguo; Li, Zhiqiang; Choudhary, Kamal; Sinnott, S. B.; Martin, C.

    2014-12-23

    Optical and Hall-effect measurements have been performed on single crystals of Pb?.??Sn?.??Se, a IV-VI mixed chalcogenide. The temperature dependent (10–300 K) reflectance was measured over 40–7000 cm?¹ (5–870 meV) with an extension to 15,500 cm?¹ (1.92 eV) at room temperature. The reflectance was fit to the Drude-Lorentz model using a single Drude component and several Lorentz oscillators. The optical properties at the measured temperatures were estimated via Kramers-Kronig analysis as well as by the Drude-Lorentz fit. The carriers were p-type with the carrier density determined by Hall measurements. A signature of valence intraband transition is found in the low-energy optical spectra. It is found that the valence-conduction band transition energy as well as the free carrier effective mass reach minimum values at 100 K, suggesting temperature-driven band inversion in the material. Density function theory calculation for the electronic band structure also make similar predictions.

  17. Temperature-driven band inversion in Pb?.??Sn?.??Se: Optical and Hall-effect studies

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

    Anand, Naween; Gu, Genda; Buvaev, Sanal; Hebard, A. F.; Tanner, D. B.; Chen, Zhiguo; Li, Zhiqiang; Choudhary, Kamal; Sinnott, S. B.; Martin, C.

    2014-12-23

    Optical and Hall-effect measurements have been performed on single crystals of Pb?.??Sn?.??Se, a IV-VI mixed chalcogenide. The temperature dependent (10–300 K) reflectance was measured over 40–7000 cm?¹ (5–870 meV) with an extension to 15,500 cm?¹ (1.92 eV) at room temperature. The reflectance was fit to the Drude-Lorentz model using a single Drude component and several Lorentz oscillators. The optical properties at the measured temperatures were estimated via Kramers-Kronig analysis as well as by the Drude-Lorentz fit. The carriers were p-type with the carrier density determined by Hall measurements. A signature of valence intraband transition is found in the low-energy opticalmore »spectra. It is found that the valence-conduction band transition energy as well as the free carrier effective mass reach minimum values at 100 K, suggesting temperature-driven band inversion in the material. Density function theory calculation for the electronic band structure also make similar predictions.« less

  18. Monte Carlo modeling of transport in PbSe nanocrystal films

    SciTech Connect (OSTI)

    Carbone, I. Carter, S. A.; Zimanyi, G. T.

    2013-11-21

    A Monte Carlo hopping model was developed to simulate electron and hole transport in nanocrystalline PbSe films. Transport is carried out as a series of thermally activated hopping events between neighboring sites on a cubic lattice. Each site, representing an individual nanocrystal, is assigned a size-dependent electronic structure, and the effects of particle size, charging, interparticle coupling, and energetic disorder on electron and hole mobilities were investigated. Results of simulated field-effect measurements confirm that electron mobilities and conductivities at constant carrier densities increase with particle diameter by an order of magnitude up to 5?nm and begin to decrease above 6?nm. We find that as particle size increases, fewer hops are required to traverse the same distance and that site energy disorder significantly inhibits transport in films composed of smaller nanoparticles. The dip in mobilities and conductivities at larger particle sizes can be explained by a decrease in tunneling amplitudes and by charging penalties that are incurred more frequently when carriers are confined to fewer, larger nanoparticles. Using a nearly identical set of parameter values as the electron simulations, hole mobility simulations confirm measurements that increase monotonically with particle size over two orders of magnitude.

  19. Temperature-driven band inversion in Pb?.??Sn?.??Se: Optical and Hall-effect studies

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

    Anand, Naween [Univ. of Florida, Gainesville, FL (United States); Gu, Genda [Brookhaven National Lab. (BNL), Upton, NY (United States); Buvaev, Sanal [Univ. of Florida, Gainesville, FL (United States); Hebard, A. F. [Univ. of Florida, Gainesville, FL (United States); Tanner, D. B. [Univ. of Florida, Gainesville, FL (United States); Chen, Zhiguo [Florida State Univ., Tallahassee, FL (United States); Li, Zhiqiang [Florida State Univ., Tallahassee, FL (United States); Choudhary, Kamal [Univ. of Florida, Gainesville, FL (United States); Sinnott, S. B. [Univ. of Florida, Gainesville, FL (United States); Martin, C. [Ramapo College, Mahwah, NJ (United States)

    2014-12-01

    Optical and Hall-effect measurements have been performed on single crystals of Pb?.??Sn?.??Se, a IV-VI mixed chalcogenide. The temperature dependent (10–300 K) reflectance was measured over 40–7000 cm?¹ (5–870 meV) with an extension to 15,500 cm?¹ (1.92 eV) at room temperature. The reflectance was fit to the Drude-Lorentz model using a single Drude component and several Lorentz oscillators. The optical properties at the measured temperatures were estimated via Kramers-Kronig analysis as well as by the Drude-Lorentz fit. The carriers were p-type with the carrier density determined by Hall measurements. A signature of valence intraband transition is found in the low-energy optical spectra. It is found that the valence-conduction band transition energy as well as the free carrier effective mass reach minimum values at 100 K, suggesting temperature-driven band inversion in the material. Density function theory calculation for the electronic band structure also make similar predictions.

  20. Nanoscale chemical phase separation in FeTe0.55Se0.45 as seen...

    Office of Scientific and Technical Information (OSTI)

    DOE PAGES Search Results Publisher's Accepted Manuscript: Nanoscale chemical phase separation in FeTe0.55Se0.45 as seen via scanning tunneling spectroscopy Prev Next Title:...

  1. Selective turn-on fluorescence detection of cyanide in water using hydrophobic CdSe quantum dots 

    E-Print Network [OSTI]

    Dryden D.T.F.; Mareque-Rivas J.C.; Galve-Gasion J.A.; Stevenson E.I.; Touceda-Varela A.

    2008-05-01

    The ability of 2,2'-bipyridine-bound copper(II) ions to quench the photoluminescence of hydrophobic CdSe quantum dots is used to create a novel, selective turn-on fluorescence cyanide sensor.

  2. 35898 Viernes 11 octubre 2002 BOE nm. 244 6. Los premios se pagarn a la terminacin de

    E-Print Network [OSTI]

    Fitze, Patrick

    relativos a edificación, y, en lo que corresponda, a los demás tipos de construcciones, en tanto no se única. Plazo de adaptación nor- mativa. Los proyectos y construcciones de nuevas edifica- ciones y otras

  3. Molecular beam epitaxial growth and characterization of Bi{sub 2}Se{sub 3}/II-VI semiconductor heterostructures

    SciTech Connect (OSTI)

    Chen, Zhiyi Zhao, Lukas; Krusin-Elbaum, Lia; Garcia, Thor Axtmann; Tamargo, Maria C.; Hernandez-Mainet, Luis C.; Deng, Haiming

    2014-12-15

    Surfaces of three-dimensional topological insulators (TIs) have been proposed to host quantum phases at the interfaces with other types of materials, provided that the topological properties of interfacial regions remain unperturbed. Here, we report on the molecular beam epitaxy growth of II-VI semiconductor–TI heterostructures using c-plane sapphire substrates. Our studies demonstrate that Zn{sub 0.49}Cd{sub 0.51}Se and Zn{sub 0.23}Cd{sub 0.25}Mg{sub 0.52}Se layers have improved quality relative to ZnSe. The structures exhibit a large relative upward shift of the TI bulk quantum levels when the TI layers are very thin (?6nm), consistent with quantum confinement imposed by the wide bandgap II-VI layers. Our transport measurements show that the characteristic topological signatures of the Bi{sub 2}Se{sub 3} layers are preserved.

  4. Depositional environments, diagenesis, and porosity development of Mississippian Chappel carbonates at Thrash and Quanah SE Fields, Hardeman County, Texas 

    E-Print Network [OSTI]

    He, Shiliang T.

    1989-01-01

    /mudstone microfacies (Thrash Field) 5) Argillaceous, spiculitic, crinoid ? bryozoan mudstone/ 32 wackestone micro facies (Quanah SE Field) 6) Dolomitic, spiculiferous, silt ? sized wackestone/mudstone microfacies (Quanah SE Field) 7) Dolomitic, cherty floatstone... crinoi. d-bryozoan mudstona/wackestone Dolomitic, spiculiferous silty wackestone/muc(ALone Well Well to morleratc Pine to medium (0. 007 mm to 0. 00 ~) silty to I'ine to 0. 00 mm) Dul row Discontinuous, p&. anar, thin, laminae Micro(null inn...

  5. Electron drift-mobility measurements in polycrystalline CuIn1-xGaxSe2 solar cells

    E-Print Network [OSTI]

    Schiff, Eric A.

    .1063/1.3692165] The chalcopyrite alloys CuIn1ÀxGaxSe2 (CIGS) are the basis of very promising thin film solar cells, with solar con conduction band states.8,9 Empirical optimization of CIGS for solar cells thus appears to have led to lowElectron drift-mobility measurements in polycrystalline CuIn1-xGaxSe2 solar cells S. A. Dinca, E. A

  6. Expanded Prussian Blue Analogues Incorporating [Re6Se8(CN)6]3-/4-Clusters: Adjusting Porosity via Charge Balance

    E-Print Network [OSTI]

    Shores, Matthew P.

    Expanded Prussian Blue Analogues Incorporating [Re6Se8(CN)6]3-/4- Clusters: Adjusting Porosity via of octahedral [M(CN)6]3-/4- complexes for the synthesis of microporous Prussian blue type solids with adjustable to be a direct expansion of Prussian blue (Fe4[Fe(CN)6]3,14H2O), with [Re6Se8(CN)6]4- clusters connected through

  7. Large single crystal quaternary alloys of IB-IIIA-Se/sub 2/ and methods of synthesizing the same

    DOE Patents [OSTI]

    Ciszek, T.F.

    1986-07-15

    New alloys of Cu/sub x/Ag/sub (1-x)/InSe/sub 2/ (where x ranges between 0 and 1 and preferably has a value of about 0.75) and CuIn/sub y/Ga/sub (1-y)/Se/sub 2/ (where y ranges between 0 and 1 and preferably has a value of about 0.90) in the form of single crystals with enhanced structure perfection, which crystals are substantially free of fissures, are disclosed. Processes are disclosed for preparing the new alloys of Cu/sub x/Ag/sub (1-x)/InSe/sub 2/. The process includes placing stoichiometric quantities of a Cu, Ag, In, and Se reaction mixture or stoichiometric quantities of a Cu, In, Ga, and Se reaction mixture in a refractory crucible in such a manner that the reaction mixture is surrounded by B/sub 2/O/sub 3/, placing the thus loaded crucible in a chamber under a high pressure atmosphere of inert gas to confine the volatile Se to the crucible, and heating the reaction mixture to its melting point. The melt can then be cooled slowly to form, by direct solidification, a single crystal with enhanced structure perfection, which crystal is substantially free of fissures.

  8. Large single crystal quaternary alloys of IB-IIIA-SE.sub.2 and methods of synthesizing the same

    DOE Patents [OSTI]

    Ciszek, Theodore F. (Evergreen, CO)

    1988-01-01

    New alloys of Cu.sub.x Ag.sub.(1-x) InSe.sub.2 (where x ranges between 0 and 1 and preferably has a value of about 0.75) and CuIn.sub.y Ga.sub.(1-y) Se.sub.2 (where y ranges between 0 and 1 and preferably has a value of about 0.90) in the form of single crystals with enhanced structure perfection, which crystals are substantially free of fissures are disclosed. Processes are disclosed for preparing the new alloys of Cu.sub.x Ag.sub.(1-x) InSe.sub.2. The process includes placing stoichiometric quantities of a Cu, Ag, In, and Se reaction mixture or stoichiometric quantities of a Cu, In, Ga, and Se reaction mixture in a refractory crucible in such a manner that the reaction mixture is surrounded by B.sub.2 O.sub.3, placing the thus loaded crucible in a chamber under a high pressure atmosphere of inert gas to confine the volatile Se to the crucible, and heating the reaction mixture to its melting point. The melt can then be cooled slowly to form, by direct solidification, a single crystal with enhanced structure perfection, which crystal is substantially free of fissures.

  9. Determination of Grain Boundary Charging in Cu(In,Ga)Se2 Thin Films: Preprint

    SciTech Connect (OSTI)

    Jiang, C. S.; Contreras, M. A.; Repins, I.; Moutinho, H. R.; Noufi, R.; Al-Jassim, M. M.

    2012-06-01

    Surface potential mapping of Cu(In,Ga)Se2 (CIGS) thin films using scanning Kelvin probe force microscopy (SKPFM) aims to understand the minority-carrier recombination at the grain boundaries (GBs) of this polycrystalline material by examining GB charging, which has resulted in a number of publications. However, the reported results are highly inconsistent. In this paper, we report on the potential mapping by measuring wide-bandgap or high-Ga-content films and by using a complementary atomic force microscopy-based electrical technique of scanning capacitance microscopy (SCM). The results demonstrate consistent, positively charged GBs on our high-quality films with minimal surface defects/charges. The potential image taken on a low-quality film with a 1.2-eV bandgap shows significantly degraded potential contrast on the GBs and degraded potential uniformity on grain surfaces, resulting from the surface defects/charges of the low-quality film. In contrast, the potential image on an improved high-quality film with the same wide bandgap shows significantly improved GB potential contrast and surface potential uniformity, indicating that the effect of surface defects is critical when examining GB charging using surface potential data. In addition, we discuss the effect of the SKPFM setup on the validity of potential measurement, to exclude possible artifacts due to improper SKPFM setups. The SKPFM results were corroborated by using SCM measurements on the films with a CdS buffer layer. The SCM image shows clear GB contrast, indicating different electrical impedance on the GB from the grain surface. Further, we found that the GB contrast disappeared when the CdS window layer was deposited after the CIGS film was exposed extensively to ambient, which was caused by the creation of CIGS surface defects by the ambient exposure.

  10. Structural, electrical and optical properties of Bi{sub 2}Se{sub 3} and Bi{sub 2}Se{sub (3-x)}Te {sub x} thin films

    SciTech Connect (OSTI)

    Augustine, Saji [Crystal Growth Laboratory, Department of Physics, Cochin University of Science and Technology, Cochin 682022, Kerala, (India) and Materials and Process Simulation Laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305701 (Korea, Republic of)]. E-mail: sajia@kaist.ac.kr; Ampili, S. [Crystal Growth Laboratory, Department of Physics, Cochin University of Science and Technology, Cochin 682022, Kerala (India); Kang, Jeung Ku [Materials and Process Simulation Laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305701 (Korea, Republic of); Mathai, Elizabeth [Crystal Growth Laboratory, Department of Physics, Cochin University of Science and Technology, Cochin 682022, Kerala (India)

    2005-08-11

    Thin films of Bi{sub 2}Se{sub 3}, Bi{sub 2}Se{sub 2.9}Te{sub 0.1}, Bi{sub 2}Se{sub 2.7}Te{sub 0.3} and Bi{sub 2}Se{sub 2.6}Te{sub 0.4} are prepared by compound evaporation. Micro structural, optical and electrical measurements are carried out on these films. X-ray diffraction pattern indicates that the as-prepared films are polycrystalline in nature with exact matching of standard pattern. The composition and morphology are determined using energy dispersive X-ray analysis and scanning electron microscopy (SEM). The optical band gap, which is direct allowed, is 0.67 eV for Bi{sub 2}Se{sub 3} thin films and the activation energy is 53 meV. Tellurium doped thin films also show strong optical absorption corresponding to a band gap of 0.70-0.78 eV. Absolute value of electrical conductivity in the case of tellurium doped thin film shows a decreasing trend with respect to parent structure.

  11. High field magnetotransport and point contact Andreev reflection measurements on CuCr{sub 2}Se{sub 4} and CuCr{sub 2}Se{sub 3}Br—Degenerate magnetic semiconductor single crystals

    SciTech Connect (OSTI)

    Borisov, K. Coey, J. M. D.; Stamenov, P.; Alaria, J.

    2014-05-07

    Single crystals of the metallically degenerate fully magnetic semiconductors CuCr{sub 2}Se{sub 4} and CuCr{sub 2}Se{sub 3}Br have been prepared by the Chemical Vapour Transport method, using either Se or Br as transport agents. The high-quality, millimetre-sized, octahedrally faceted, needle- and platelet-shaped crystals are characterised by means of high field magnetotransport (?{sub 0}H? 14?T) and Point Contact Andreev Reflection. The relatively high spin polarisation observed |P|>0.56, together with the relatively low minority carrier effective mass of 0.25 m{sub e}, and long scattering time  10{sup ?13}?s, could poise these materials for integration in low- and close-to-room temperature minority injection bipolar heterojunction transistor demonstrations.

  12. Quasiparticle interference, quasiparticle interactions, and the origin of the charge density wave in 2H-NbSe?

    SciTech Connect (OSTI)

    Arguello, C. J. [Columbia Univ., New York, NY (United States); Valla, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Rosenthal, E. P. [Columbia Univ., New York, NY (United States); Andrade, E. F. [Columbia Univ., New York, NY (United States); Jin, W. [Columbia Univ., New York, NY (United States); Yeh, P. C. [Columbia Univ., New York, NY (United States); Zaki, N. [Columbia Univ., New York, NY (United States); Jia, S. [Princeton Univ., NJ (United States); Cava, R. J. [Princeton Univ., NJ (United States); Fernandes, R. M. [Univ., of Minnesota, Minneapolis, MN (United States); Millis, A. J. [Columbia Univ., New York, NY (United States); Osgood, Jr., R. M. [Columbia Univ., New York, NY (United States); Princeton Univ., Princeton, NJ (United States); Pasupathy, A. N. [Columbia Univ., New York, NY (United States)

    2015-01-01

    We show that a small number of intentionally introduced defects can be used as a spectroscopic tool to amplify quasiparticle interference in 2H-NbSe?, that we measure by scanning tunneling spectroscopic imaging. We show from the momentum and energy dependence of the quasiparticle interference that Fermi surface nesting is inconsequential to charge density wave formation in 2H-NbSe?. We demonstrate that by combining quasiparticle interference data with additional knowledge of the quasiparticle band structure from angle resolved photoemission measurements, one can extract the wavevector and energy dependence of the important electronic scattering processes thereby obtaining direct information both about the fermiology and the interactions. In 2H-NbSe?, we use this combination to show that the important near-Fermi-surface electronic physics is dominated by the coupling of the quasiparticles to soft mode phonons at a wave vector different from the CDW ordering wave vector.

  13. Quasiparticle interference, quasiparticle interactions, and the origin of the charge density wave in 2H-NbSe?

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

    Arguello, C. J.; Valla, T.; Rosenthal, E. P.; Andrade, E. F.; Jin, W.; Yeh, P. C.; Zaki, N.; Jia, S.; Cava, R. J.; Fernandes, R. M.; et al

    2015-01-20

    We show that a small number of intentionally introduced defects can be used as a spectroscopic tool to amplify quasiparticle interference in 2H-NbSe?, that we measure by scanning tunneling spectroscopic imaging. We show from the momentum and energy dependence of the quasiparticle interference that Fermi surface nesting is inconsequential to charge density wave formation in 2H-NbSe?. We demonstrate that by combining quasiparticle interference data with additional knowledge of the quasiparticle band structure from angle resolved photoemission measurements, one can extract the wavevector and energy dependence of the important electronic scattering processes thereby obtaining direct information both about the fermiology andmore »the interactions. In 2H-NbSe?, we use this combination to show that the important near-Fermi-surface electronic physics is dominated by the coupling of the quasiparticles to soft mode phonons at a wave vector different from the CDW ordering wave vector.« less

  14. Fabrication and characterization of Cu(In,Ga)Se{sub 2} p-channel thin film transistors

    SciTech Connect (OSTI)

    Zhu, Xiaobo [Graduate Institute of Electronics Engineering and Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan (China); Liu, C. W., E-mail: chee@cc.ee.ntu.edu.tw [Graduate Institute of Electronics Engineering, Graduate Institute of Photonics and Optoelectronics, Department of Electrical Engineering, and Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan and National Nano Device Labs, Hsinchu, Taiwan (China)

    2014-10-06

    Cu(In,Ga)Se{sub 2} thin film transistors are demonstrated with the on-off ratio of ?10{sup 3} and the saturation hole mobility of 1.8?cm{sup 2}/V-s. Due to the high hole concentration (?5?×?10{sup 17?}cm{sup ?3}), the channel needs to be etched to turn off for the accumulation mode operation. The Cu(In,Ga)Se{sub 2} film after etching reveals a larger mobility, and a narrower (112) X-ray diffraction line than the original thick layer, indicating the better crystallinity of the initial growth as compared to the subsequent Cu(In,Ga)Se{sub 2} layer. Both the hole concentration and the saturation mobility increase with the decreasing Cu/(In?+?Ga) ratio probably due to the effect of Cu vacancies.

  15. Quasiparticle interference, quasiparticle interactions, and the origin of the charge density wave in 2H-NbSe?

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

    Arguello, C. J. [Columbia Univ., New York, NY (United States); Valla, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Rosenthal, E. P. [Columbia Univ., New York, NY (United States); Andrade, E. F. [Columbia Univ., New York, NY (United States); Jin, W. [Columbia Univ., New York, NY (United States); Yeh, P. C. [Columbia Univ., New York, NY (United States); Zaki, N. [Columbia Univ., New York, NY (United States); Jia, S. [Princeton Univ., NJ (United States); Cava, R. J. [Princeton Univ., NJ (United States); Fernandes, R. M. [Univ., of Minnesota, Minneapolis, MN (United States); Millis, A. J. [Columbia Univ., New York, NY (United States); Osgood, Jr., R. M. [Columbia Univ., New York, NY (United States); Princeton Univ., Princeton, NJ (United States); Pasupathy, A. N. [Columbia Univ., New York, NY (United States)

    2015-01-01

    We show that a small number of intentionally introduced defects can be used as a spectroscopic tool to amplify quasiparticle interference in 2H-NbSe?, that we measure by scanning tunneling spectroscopic imaging. We show from the momentum and energy dependence of the quasiparticle interference that Fermi surface nesting is inconsequential to charge density wave formation in 2H-NbSe?. We demonstrate that by combining quasiparticle interference data with additional knowledge of the quasiparticle band structure from angle resolved photoemission measurements, one can extract the wavevector and energy dependence of the important electronic scattering processes thereby obtaining direct information both about the fermiology and the interactions. In 2H-NbSe?, we use this combination to show that the important near-Fermi-surface electronic physics is dominated by the coupling of the quasiparticles to soft mode phonons at a wave vector different from the CDW ordering wave vector.

  16. Quasiparticle interference, quasiparticle interactions, and the origin of the charge density wave in 2H–NbSe2

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

    Arguello, C. J.; Rosenthal, E. P.; Andrade, E. F.; Jin, W.; Yeh, P. C.; Zaki, N.; Jia, S.; Cava, R. J.; Fernandes, R. M.; Millis, A. J.; et al

    2015-01-21

    We show that a small number of intentionally introduced defects can be used as a spectroscopic tool to amplify quasiparticle interference in 2H-NbSe?, that we measure by scanning tunneling spectroscopic imaging. We show from the momentum and energy dependence of the quasiparticle interference that Fermi surface nesting is inconsequential to charge density wave formation in 2H-NbSe?. Thus, we demonstrate that by combining quasiparticle interference data with additional knowledge of the quasiparticle band structure from angle resolved photoemission measurements, one can extract the wavevector and energy dependence of the important electronic scattering processes thereby obtaining direct information both about the fermiologymore »and the interactions. In 2H-NbSe?, we use this combination to show that the important near-Fermi-surface electronic physics is dominated by the coupling of the quasiparticles to soft mode phonons at a wave vector different from the CDW ordering wave vector.« less

  17. Van der Waals Epitaxial Growth of Single-Crystal Two-Dimensional GaSe on Graphene

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

    Li, Xufan; Basile, Leonardo; Huang, Bing; Ma, Cheng; Lee, Jaekwang; Vlassiouk, Ivan V.; Puretzky, Alexander A.; Lin, Ming-Wei; Chi, Miaofang; Idrobo Tapia, Juan Carlos; et al

    2015-07-22

    Two-dimensional (2D) van der Waals (vdW) heterostructures are a family of artificially-structured materials that promise tunable optoelectronic properties for devices with enhanced functionalities. Compared to stamping, direct epitaxy of vdW heterostructures is ideal for clean interlayer interfaces and scalable device fabrication. Here, we explore the synthesis and preferred orientations of 2D GaSe atomic layers on graphene (Gr) by vdW epitaxy. Guided by the wrinkles on graphene, GaSe nuclei form that share a predominant lattice orientation. Due to vdW epitaxial growth many nuclei grow as perfectly aligned crystals and coalesce to form large (tens of microns), single-crystal flakes. Through theoretical investigationsmore »of interlayer energetics, and measurements of preferred orientations by atomic-resolution STEM and electron diffraction, a 10.9 interlayer rotation of the GaSe lattice with respect to the underlying graphene is found to be the most energetically preferred vdW heterostructure with the largest binding energy and the longest-range ordering. These GaSe/Gr vdW heterostructures exhibit an enhanced Raman E21g band of monolayer GaSe along with highly-quenched photoluminescence due to strong charge transfer. Despite the very large lattice mismatch of GaSe/Gr through vdW epitaxy, the predominant orientation control and convergent formation of large single-crystal flakes demonstrated here is promising for the scalable synthesis of large-area vdW heterostructures for the development of new optical and optoelectronic devices.« less

  18. Van der Waals epitaxial growth of two-dimensional single-crystalline GaSe domains on graphene

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

    Li, Xufan; Basile, Leonardo; Huang, Bing; Ma, Cheng; Lee, Jaekwang; Vlassiouk, Ivan V.; Puretzky, Alexander A.; Lin, Ming -Wei; Chi, Miaofang; Idrobo Tapia, Juan Carlos; et al

    2015-07-22

    Two-dimensional (2D) van der Waals (vdW) heterostructures are a family of artificially-structured materials that promise tunable optoelectronic properties for devices with enhanced functionalities. Compared to stamping, direct epitaxy of vdW heterostructures is ideal for clean interlayer interfaces and scalable device fabrication. Here, we explore the synthesis and preferred orientations of 2D GaSe atomic layers on graphene (Gr) by vdW epitaxy. Guided by the wrinkles on graphene, GaSe nuclei form that share a predominant lattice orientation. Due to vdW epitaxial growth many nuclei grow as perfectly aligned crystals and coalesce to form large (tens of microns), single-crystal flakes. Through theoretical investigationsmore »of interlayer energetics, and measurements of preferred orientations by atomic-resolution STEM and electron diffraction, a 10.9 interlayer rotation of the GaSe lattice with respect to the underlying graphene is found to be the most energetically preferred vdW heterostructure with the largest binding energy and the longest-range ordering. These GaSe/Gr vdW heterostructures exhibit an enhanced Raman E21g band of monolayer GaSe along with highly-quenched photoluminescence due to strong charge transfer. Despite the very large lattice mismatch of GaSe/Gr through vdW epitaxy, the predominant orientation control and convergent formation of large single-crystal flakes demonstrated here is promising for the scalable synthesis of large-area vdW heterostructures for the development of new optical and optoelectronic devices.« less

  19. Observation of an electron band above the Fermi level in FeTe?.??Se?.?? from in-situ surface doping

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

    Zhang, P.; Richard, P.; Xu, N.; Xu, Y. -M.; Ma, J.; Qian, T.; Fedorov, A. V.; Denlinger, J. D.; Gu, G. D.; Ding, H.

    2014-10-27

    We used in-situ potassium (K) evaporation to dope the surface of the iron-based superconductor FeTe?.??Se?.??. The systematic study of the bands near the Fermi level confirms that electrons are doped into the system, allowing us to tune the Fermi level of this material and to access otherwise unoccupied electronic states. In particular, we observe an electron band located above the Fermi level before doping that shares similarities with a small three-dimensional pocket observed in the cousin, heavily-electron-doped KFe??xSe? compound.

  20. Critical current density and mechanism of vortex pinning in KxFe2-ySe? doped with S

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

    Lei, Hechang; Petrovic, C.

    2011-08-01

    We report the critical current density Jc in KxFe2-ySe2-zSz crystals. The Jc can be enhanced significantly with optimal S doping (z=0.99). For K0.70(7)Fe1.55(7)Se1.01(2)S0.99(2), the weak fishtail effect is found for H II c. The normalized vortex pinning forces follow the scaling law with a maximum position at 0.41 of the reduced magnetic field. These results demonstrate that the small size normal point defects dominate the vortex pinning mechanism.

  1. Enhancement of surface phonon modes in the Raman spectrum of ZnSe nanoparticles on adsorption of 4-mercaptopyridine

    SciTech Connect (OSTI)

    Islam, Syed K.; Lombardi, John R.

    2014-02-21

    By chemically etching a thin film of crystalline ZnSe with acid, we observe a strong Raman enhancement of the surface phonon modes of ZnSe on adsorption of a molecule (4-mercaptopyridine). The surface is composed of oblate hemi-ellipsoids, which has a large surface-to-bulk ratio. The assignment of the observed modes (at 248 and 492 cm{sup ?1}) to a fundamental and first overtone of the surface optical mode is consistent with observations from high-resolution electron energy loss spectroscopy as well as calculations.

  2. Synthesis and Phase Transformation of In2Se3 and CuInSe2 Nanowires Hailin Peng, David T. Schoen, Stefan Meister, Xiao Feng Zhang, and Yi Cui*,

    E-Print Network [OSTI]

    Cui, Yi

    with a controllable composition modulation can afford ordered p-n junctions and continuous charge carrier transport pathways without deadends, which is an advantage over the random p-n junctions. Therefore, NW solar cells10:3 confirming the chemical composition of In2Se3. High- resolution TEM (HRTEM) (Figure 1c) and selected

  3. DOI: 10.1002/adma.200701125 Light-Induced Charge Transfer in Pyrene/CdSe-SWNT Hybrids**

    E-Print Network [OSTI]

    Gruner, George

    DOI: 10.1002/adma.200701125 Light-Induced Charge Transfer in Pyrene/CdSe-SWNT Hybrids solar cells.[20­24] Holes are transported along the polymer chains and electrons hop along the nanopar to low hole mobility and hence limit- ing the solar cell efficiency. Semiconductor nanorod-polymer hybrid

  4. Transition threshold in Ge{sub x}Sb{sub 10}Se{sub 90?x} glasses

    SciTech Connect (OSTI)

    Wei, Wen-Hou [Department of Applied Physics, Chongqing University, Chongqing 401331 (China); Centre for Ultrahigh Bandwidth Devices for Optical Systems (CUDOS), Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Fang, Liang, E-mail: lfang@cqu.edu.cn [Department of Applied Physics, Chongqing University, Chongqing 401331 (China); Shen, Xiang [Laboratory of Infrared Material and Devices, Advanced Technology Research Institute, Ningbo University, Ningbo 315211 (China); Wang, Rong-Ping [Centre for Ultrahigh Bandwidth Devices for Optical Systems (CUDOS), Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

    2014-03-21

    Ge{sub x}Sb{sub 10}Se{sub 90?x} glasses with Ge content from 7.5 to 32.5?at.?% have been prepared by melt-quench technique, and the physical parameters including glass transition temperature (T{sub g}), density (?), compactness (C), shear elastic moduli (C{sub s}), compression elastic moduli (C{sub c}), refractive index (n), and optical bandgap (E{sub g}) have been investigated. While all these physical parameters show threshold behavior in the glass with a chemically stoichiometric composition. Raman spectra analysis also indicates that, with increasing Ge content, Se-chains or rings gradually disappear until all Se-atoms are consumed in the glass with a chemically stoichiometric composition. With further increasing Ge content, homopolar Ge-Ge and Sb-Sb bonds are formed and the chemical order in the glasses is violated. The threshold behavior of the physical properties in the Ge{sub x}Sb{sub 10}Se{sub 90?x} glasses can be traced to demixing of networks above the chemically stoichiometric composition.

  5. Materials data requirements for high power target design E. Noah, 4th HPTW, Malm, SE, 2-6 May 2011

    E-Print Network [OSTI]

    McDonald, Kirk

    Materials data requirements for high power target design E. Noah, 4th HPTW, Malmö, SE, 2-6 May 2011 Materials Data Requirements For High Power Target Design E. Noah, C. Kharoua, F. Plewinski, P. Sabbagh ESS Target Division 4th HPTW May 2-6, 2011, Malmö #12;Materials data requirements for high power

  6. Measuring charge trap occupation and energy level in CdSe/ZnS quantum dots using a scanning tunneling microscope

    E-Print Network [OSTI]

    Hummon, M. R.

    We use a scanning tunneling microscope to probe single-electron charging phenomena in individual CdSe/ZnS (core/shell) quantum dots (QDs) at room temperature. The QDs are deposited on top of a bare Au thin film and form a ...

  7. OligoceneMiocene basin evolution in SE Anatolia, Turkey: constraints on the closure of the eastern Tethys gateway

    E-Print Network [OSTI]

    Utrecht, Universiteit

    Oligocene­Miocene basin evolution in SE Anatolia, Turkey: constraints on the closure of the eastern, The Netherlands 3 Department of Geology, Firat University, Elazig, Turkey 4 Natural History Museum Vienna, Austria, we focus on the evolution of Oligocene and Miocene foreland basins in the southernmost part of Turkey

  8. Wind profile above the surface boundary layer S.-E. Gryning (1), E. Batchvarova (2) and B. Brmmer (3)

    E-Print Network [OSTI]

    Wind profile above the surface boundary layer S.-E. Gryning (1), E. Batchvarova (2) and B. Brümmer in predictions of the wind profile in the lowest hundreds me- ters of the atmosphere, being connected to the general increase in height of structures such as bridges, high houses and wind turbines. The hub height

  9. 104 Royal Swedish Academy of Sciences 2001 Ambio Vol. 30 No. 2, March 2001 http://www.ambio.kva.se

    E-Print Network [OSTI]

    Thomas, Valerie

    ://www.ambio.kva.se ENVIRONMENTALISM AND ANTI-SOVIET POLITICS The environmental movement was central to the political trans- formation came to power, practically ensured that environmental issues would become a major focal point- session.... Green feelings now run as deep, and are as politically challenging, as anywhere in the world

  10. Spin glass and semiconducting behavior in one-dimensional BaFe2-dSe3 (d~2) crystals

    SciTech Connect (OSTI)

    Saparov, Bayrammurad I [ORNL; Calder, Stuart A [ORNL; Sipos, Balazs [ORNL; Cao, Huibo [ORNL; Chi, Songxue [ORNL; Singh, David J [ORNL; Christianson, Andrew D [ORNL; Lumsden, Mark D [ORNL; Sefat, A. S. [Oak Ridge National Laboratory (ORNL)

    2011-01-01

    We investigate the physical properties and electronic structure of BaFe{sub 1.79(2)}Se{sub 3} crystals, which were grown out of tellurium flux. The crystal structure of the compound, an iron-deficient derivative of the ThCr{sub 2}Si{sub 2}-type, is built upon edge-shared FeSe{sub 4} tetrahedra fused into double chains. The semiconducting BaFe{sub 1.79(2)}Se{sub 3} ({rho}{sub 295K} = 0.18 {Omega} {center_dot} cm and E{sub g} = 0.30 eV) does not order magnetically; however, there is evidence for short-range magnetic correlations of spin glass type (T{sub f} {approx} 50 K) in magnetization, heat capacity, and neutron diffraction results. A one-third substitution of selenium with sulfur leads to a slightly higher electrical conductivity ({rho}{sub 295K } = 0.11 {Omega} {center_dot} cm and E{sub g} = 0.22 eV) and a lower spin glass freezing temperature (T{sub f} {approx} 15 K), corroborating with higher electrical conductivity reported for BaFe{sub 2}S{sub 3}. According to the electronic structure calculations, BaFe{sub 2}Se{sub 3} can be considered as a one-dimensional ladder structure with a weak interchain coupling.

  11. Journal of Crystal Growth 310 (2008) 29872994 Reaction kinetics of CuGaSe2 formation from

    E-Print Network [OSTI]

    Anderson, Timothy J.

    2008-01-01

    of polycrystalline thin-film Cu(InxGa1Àx)Se2 (CIGS) solar cells achieved over the past several decades appears. Copper gallium diselenide; B3. Solar cells 1. Introduction The continuous improvement in the efficiency for the top cell in a CIGS tandem structure [2­4], given its suitable band gap energy (1.68 eV), process

  12. Toward microscale Cu,,In,Ga...Se2 solar cells for efficient conversion and optimized material usage: Theoretical evaluation

    E-Print Network [OSTI]

    Boyer, Edmond

    develop a model to predict the performances of microscale Cu In,Ga Se2 CIGS solar cells under concentrated limiting factor for concentration on CIGS solar cells. This model can be used to extract the value associated with the operation of microscale CIGS solar cells are studied. The optimum concentration ratio

  13. The effect of Na in polycrystalline and epitaxial single-crystal CuIn1xGaxSe2

    E-Print Network [OSTI]

    Rockett, Angus

    online 15 December 2004 Abstract Na is found to improve the performance of Cu(In,Ga)Se2 (CIGS) solar the highest efficiency, exceeding 19%, of any thin film polycrystalline solar cell [1]. The diodes work well cells although the mechanism is not clear. This paper briefly reviews some of the observations on Na

  14. XIII JORNADAS DE PARALELISMO--LLEIDA, SEPTIEMBRE 2002 1 Resumen --Se realiza una breve introduccin a los

    E-Print Network [OSTI]

    Miguel-Alonso, José

    introducción a los algoritmos de estimación de distribuciones, dentro del ámbito de la computación evolutiva. Al aplicar estos algoritmos a un problema de concordancia inexacta de grafos, se observan largos observado de 4,53. Palabras clave -- Algoritmos de estimación de distribuciones (EDAs), computación

  15. Deformation of a pervasively molten middle crust: insights from the neoproterozoic Ribeira-Aracuai orogen (SE Brazil)

    E-Print Network [OSTI]

    Tommasi, Andrea

    -Arac¸uai´ orogen (SE Brazil) Alain Vauchez,1 Marcos Egydio-Silva,2 Marly Babinski,2 Andre´a Tommasi,1 Alexandre, 562 Cidade Universitaria, 05508-900 Sa~o Paulo, SP, Brazil; 3 Instituto de Geocie^ncias Universidade Federal de Minas Gerais, Av. Anto^nio Carlos, 6627 Pampulha, 31270-901 Belo Horizonte, MG, Brazil; 4

  16. Shear wave splitting in SE Brazil: an eect of active or fossil upper mantle ow, or both?

    E-Print Network [OSTI]

    Barruol, Guilhem

    Shear wave splitting in SE Brazil: an e¡ect of active or fossil upper mantle £ow, or both?§ Maggy, Brazil c Universidade de SaBrazil Received 26 the structure of the upper mantle beneath southeastern Brazil using teleseismic shear wave splitting

  17. Efficient band alignment for ZnxCd1xSe QD-sensitized TiO2 solar cells

    E-Print Network [OSTI]

    Cao, Guozhong

    dots (QDs), such as CdS,2,3 CdTe,4­6 PbS,7,8 PbSe,9,10 and InP,11,12 have recently been extensively in the enhancement of the power conversion efficiency and device stability. As an alternative, semiconductor quantum

  18. Photoluminescence Enhancement in CdSe/ZnS–DNA linked–Au 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.

  19. DETERMINATION OF BACK CONTACT BARRIER HEIGHT IN Cu(In,Ga)(Se,S)2 AND CdTe SOLAR CELLS

    E-Print Network [OSTI]

    Sites, James R.

    DETERMINATION OF BACK CONTACT BARRIER HEIGHT IN Cu(In,Ga)(Se,S)2 AND CdTe SOLAR CELLS Galymzhan T-contact metallization. The input data is the current- voltage (J-V) curves for the solar cell measured over a range point technique and apply it to specific solar-cell examples. The range of Jt that can be practically

  20. Journal of Crystal Growth 281 (2005) 209219 Effect of a CuSe secondary phase on the epitaxial

    E-Print Network [OSTI]

    Anderson, Timothy J.

    2005-01-01

    -cost thin-film solar cells. The advantages of this class of materials include their high that appears during epitaxial growth of CuInSe2 (CIS) films on (1 0 0) GaAs substrates was investigated. CIS films with different copper to indium molar ratios were deposited on (1 0 0) GaAs substrates at 360 1C

  1. Pgina Inicial Empresas Start-ups portuguesas mostram-se hoje a investidores suecos em Lisboa Empresas criadas em

    E-Print Network [OSTI]

    Instituto de Sistemas e Robotica

    Energia Internacional O Governo quer cortar os salários também nas empresas públicas. Mas ao contrário do ano... LEIA TUDO Últimas Telecom Construção Energia Internacional | Empresas criadas em PortugalPágina Inicial Empresas Start-ups portuguesas mostram-se hoje a investidores suecos em Lisboa

  2. Band-gap grading in Cu(In,Ga)Se2 solar cells M. Gloeckler and J. R. Sites

    E-Print Network [OSTI]

    Sites, James R.

    Band-gap grading in Cu(In,Ga)Se2 solar cells M. Gloeckler and J. R. Sites Department of Physics solar cells, and some researchers have asserted that these fields can enhance performance. The experimental evidence that grading improves device performance, however, has not been compelling, mostly

  3. Simulation of Polycrystalline Cu(In,Ga)Se2 Solar Cells in Two Dimensions Markus Gloeckler, Wyatt K. Metzger1

    E-Print Network [OSTI]

    Sites, James R.

    Simulation of Polycrystalline Cu(In,Ga)Se2 Solar Cells in Two Dimensions Markus Gloeckler, Wyatt K) solar cells and its effects on solar-cell performance. The simulations predict that (1) for device cells have nearly reached 20% [1]. It is often argued that these improvements have been achieved despite

  4. RVF The Swedish Association of Waste Management www.rvf.se of the Swedish report "Frbrnning av avfall en

    E-Print Network [OSTI]

    Columbia University

    RVF ­ The Swedish Association of Waste Management www.rvf.se 1 (19) Summary of the Swedish report knowledge in this area, the Swedish Association of Waste Management (RVF) has taken the initiative within the areas of waste management and recycling. The owners of Sweden's 22 waste incineration plants

  5. Biologically programmed synthesis of core-shell CdSe/ZnS nanocrystalsw Shailendra Singh,ab

    E-Print Network [OSTI]

    Chen, Wilfred

    not only directs the nucleation of inorganic materials, but also controls the crystal structure and sizeBiologically programmed synthesis of core-shell CdSe/ZnS nanocrystalsw Shailendra Singh report of core-shell semiconductor nanocrystal synthesis using a peptide template. Type II

  6. Information Technologies Activity Report MA Y SE P T E M B E R 2 0 14

    E-Print Network [OSTI]

    Firestone, Jeremy

    Information Technologies Activity Report MA Y ­ SE P T E M B E R 2 0 14 Farber HPC cluster now; · Registrar's Office; · Institutional Research; and 1 #12;Information Technologies Activity Report May available Building on the success of the Mills High-Performance Computing (HPC) cluster, UD Information

  7. 1. General description The NXP Semiconductors SE97 measures temperature from -40 C and +125 C and

    E-Print Network [OSTI]

    Berns, Hans-Gerd

    the Temp Sensor (TS) on DIMM allows accurate monitoring of the DIMM module temperature to better estimate1. General description The NXP Semiconductors SE97 measures temperature from -40 °C and +125 °C on a Dual In-Line Memory Module (DIMM) measuring the DRAM temperature in accordance with the new JEDEC (JC

  8. Benefits of Carrier Pocket Anisotropy to Thermoelectric Performance: The case of p-type AgBiSe2

    SciTech Connect (OSTI)

    Parker, David S; May, Andrew F; Singh, David J

    2015-01-01

    We study theoretically the effects of anisotropy on the thermoelectric performance of p-type AgBiSe2. We present an apparent realization of the thermoelectric benefits of one-dimensional plate-like carrier pocket anisotropy in the valence band of this material. Based on first principles calculations we find a substantial anisotropy in the electronic structure, likely favorable for thermoelectric performance, in the valence bands of the hexagonal phase of the silver chalcogenide thermoelectric AgBiSe2, while the conduction bands are more isotropic, and in our experiments do not attain high performance. AgBiSe2 has already exhibited a ZT value of 1.5 in a high-temperature disordered fcc phase, but room-temperature performance has not been demonstrated. We develop a theory for the ability of anisotropy to decouple the density-of-states and conductivity effective masses, pointing out the influence of this effect in the high performance thermoelectrics Bi2Te3 and PbTe. From our first principles and Boltzmann transport calculations we find that p-type AgBiSe2 has substantial promise as a room temperature thermoelectric, and estimate its performance.

  9. Genetic signature of a recent invasion: The ragged sea hare Bursatella leachii in Mar Menor (SE Spain)

    E-Print Network [OSTI]

    Borges, Rita

    Genetic signature of a recent invasion: The ragged sea hare Bursatella leachii in Mar Menor (SE, Portugal b Departamento de Ciencias del Mar y Biología Aplicada, Universidad de Alicante, Campus de San hypothesis for the origin of invasions is that colonization by invasive species is most often associated

  10. Vegetation and climate dynamics during the early Middle Miocene from Lake Sinj (Dinaride Lake System, SE Croatia)

    E-Print Network [OSTI]

    Jiménez-Moreno, Gonzalo

    System, SE Croatia) Gonzalo Jiménez-Moreno a, , Oleg Mandic b , Mathias Harzhauser b , Davor Paveli c of Zagreb, Pierottijeva 6, HR-10000 Zagreb, Croatia A B S T R A C TA R T I C L E I N F O Article history 2008 Keywords: pollen vegetation climate change Miocene Croatia Pollen data from sediments from

  11. 6 mW and 30 mW laser threshold for respectively 1st Brillouin Stokes order in a Ge10As24Se68 chalcogenide fiber.

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    fiber made of chalcogenide glass to make a BFL [5]. A 3 meter long suspended-core AsSe chalcogenide have replaced the suspended-core chalcogenide AsSe previously used by a microstructured Ge10As24Se68 diameter of the AsSe suspended- core fiber is 240 µm and the core diameter d is 3.8 µm. The mode effective

  12. Chemical order in Ge{sub x}As{sub y}Se{sub 1-x-y} glasses probed by high resolution X-ray photoelectron spectroscopy

    SciTech Connect (OSTI)

    Xu, S. W. [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); College of Applied Sciences, Beijing University of Technology, Beijing100124 (China); Wang, R. P.; Luther-Davies, B. [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Kovalskiy, A. [Department of Physics and Astronomy, Austin Peay State University, Clarksville, Tennessee 37043 (United States); Miller, A. C.; Jain, H. [Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, Pennsylvania 18015-3195 (United States)

    2014-02-28

    We have measured high-resolution x-ray photoelectron spectra of Ge{sub x}As{sub y}Se{sub 1-x-y} glasses with a mean coordination number (MCN) from 2.2 to 2.78. The valence band spectra showed that a number of Se–Se–Se trimers can be found in Se-rich samples, whilst multiband features induced by phase separation can be observed in extremely Se-poor samples. When the Ge, As, and Se 3d spectra were decomposed into several doublets, which correspond, respectively, to different chemical environments, the perfect AsSe{sub 3/2} pyramidal and GeSe{sub 4/2} tetrahedral structures in Se-rich samples gradually evolved into defect structures, including As–As and Ge–Ge homopolar bonds, with increasing Ge and As concentrations. Two transition-like features were found at MCN?=?2.5 and 2.64–2.72 that correspond first to the disappearance of Se-chains in the glass network and, subsequently, destruction of the perfect GeSe{sub 4/2} tetrahedral structures, respectively.

  13. Comparative Study of the Defect Point Physics and Luminescence of the Kesterites Cu2ZnSnS4 and Cu2ZnSnSe4 and Chalcopyrite Cu(In,Ga)Se2: Preprint

    SciTech Connect (OSTI)

    Romero, M. J.; Repins, I.; Teeter, G.; Contreras, M.; Al-Jassim, M.; Noufi, R.

    2012-08-01

    In this contribution, we present a comparative study of the luminescence of the kesterites Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) and their related chalcopyrite Cu(In,Ga)Se2 (CIGSe). Luminescence spectroscopy suggests that the electronic properties of Zn-rich, Cu-poor kesterites (both CZTS and CZTSe) and Cu-poor CIGSe are dictated by fluctuations of the electrostatic and chemical potentials. The large redshift in the luminescence of grain boundaries in CIGSe, associated with the formation of a neutral barrier is clearly observed in CZTSe, and, to some extent, in CZTS. Kesterites can therefore replicate the fundamental electronic properties of CIGSe.

  14. Magneto-optical characterizations of FeTe???Se??? thin films with critical current density over 1 MA/cm²

    SciTech Connect (OSTI)

    Sun, Yue; Li, Qiang; Tsuchiya, Yuji; Pyon, Sunseng; Tamegai, Tsuyoshi; Zhang, Cheng; Ozaki, Toshinori

    2015-01-01

    We performed magneto-optical (MO) measurements on FeTe???Se??? thin films grown on LaAlO? (LAO) and Yttria-stabilized zirconia (YSZ) single-crystalline substrates. These thin films show superconducting transition temperature Tc ~19 K, 4 K higher than the bulk sample. Typical roof-top patterns can be observed in the MO images of thin films grown on LAO and YSZ, from which a large and homogeneous critical current density Jc ~ 3 - 4 x 10? A/cm² at 5 K was obtained. Magnetic flux penetration measurement reveals that the current is almost isotropically distributed in the two thin films. Compared with bulk crystals, FeTe???Se??? thin film demonstrates not only higher Tc, but also much larger Jc, which is attractive for applications.

  15. Properties of the 0{sub 2}{sup +} state and isospin excitation in the N=Z nucleus {sup 68}Se

    SciTech Connect (OSTI)

    Al-Khudair, Falih H.; Li, Y. S.; Long, G. L. [Key Laboratory for Quantum Information and Measurements and Department of Physics, Tsinghua University, Beijing 100084 (China); Center of Nuclear Theory, Lanzhou National Laboratory of Accelerators, Lanzhou 730000 (China)

    2007-05-15

    Band structure and electromagnetic transition properties of the low-lying states in the N=Z {sup 68}Se nucleus were studied within the framework of interacting boson model 3. The isospin excitation states with T>T{sub Z} are identified. The M1 and E2 matrix elements for low-lying states have been investigated and were used to identify the low-lying mixed symmetry states. Special attention is given to the occurrence of 0{sub 2}{sup +} state, recently predicted by the projected shell-model (PSM) calculation. The present predicted spectrum for {sup 68}Se is close to the recent PSM results and confirms the results for the 0{sub 2}{sup +} state. The calculated results are compared with available experimental data, and they are in general good agreement.

  16. SPECTROSCOPIC INVESTIGATION OF (NH4)2S TREATED GaSeTe FOR RADIATION DETECTOR APPLICATIONS

    SciTech Connect (OSTI)

    Nelson, A; Laurence, T; Conway, A; Behymer, E; Sturm, B; Voss, L; Nikolic, R; Payne, S; Mertiri, A; Pabst, G; Mandal, K; Burger, A

    2009-08-04

    The surface of the layered III-VI chalcogenide semiconductor GaSeTe was treated with (NH{sub 4}){sub 2}S at 60 C to modify the surface chemistry and determine the effect on transport properties. Room temperature photoluminescence (PL) measurements were used to assess the effect of the (NH{sub 4}){sub 2}S treatment on surface defect states. Evaluation of the subsequent surface chemistry was performed with high-resolution core-level photoemission measurements. Metal overlayers were deposited on the (NH{sub 4}){sub 2}S treated surfaces and the I-V characteristics were measured. The measurements were correlated to understand the effect of (NH{sub 4}){sub 2}S modification of the interfacial electronic structure with the goal of optimizing the metal/GaSeTe interface for radiation detector devices.

  17. Magneto-optical characterizations of FeTe???Se??? thin films with critical current density over 1 MA/cm²

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

    Sun, Yue; Li, Qiang; Tsuchiya, Yuji; Pyon, Sunseng; Tamegai, Tsuyoshi; Zhang, Cheng; Ozaki, Toshinori

    2014-12-03

    We performed magneto-optical (MO) measurements on FeTe???Se??? thin films grown on LaAlO? (LAO) and Yttria-stabilized zirconia (YSZ) single-crystalline substrates. These thin films show superconducting transition temperature Tc ~19 K, 4 K higher than the bulk sample. Typical roof-top patterns can be observed in the MO images of thin films grown on LAO and YSZ, from which a large and homogeneous critical current density Jc ~ 3 - 4 x 10? A/cm² at 5 K was obtained. In this study, magnetic flux penetration measurement reveals that the current is almost isotropically distributed in the two thin films. Compared with bulk crystals,more »FeTe???Se??? thin film demonstrates not only higher Tc, but also much larger Jc, which is attractive for applications.« less

  18. All-metallic electrically gated 2H-TaSe{sub 2} thin-film switches and logic circuits

    SciTech Connect (OSTI)

    Renteria, J.; Jiang, C.; Yan, Z.; Samnakay, R.; Goli, P.; Pope, T. R.; Salguero, T. T.; Wickramaratne, D.; Lake, R. K.; Khitun, A. G.; Balandin, A. A.

    2014-01-21

    We report the fabrication and performance of all-metallic three-terminal devices with tantalum diselenide thin-film conducting channels. For this proof-of-concept demonstration, the layers of 2H-TaSe{sub 2} were exfoliated mechanically from single crystals grown by the chemical vapor transport method. Devices with nanometer-scale thicknesses exhibit strongly non-linear current-voltage characteristics, unusual optical response, and electrical gating at room temperature. We have found that the drain-source current in thin-film 2H-TaSe{sub 2}–Ti/Au devices reproducibly shows an abrupt transition from a highly resistive to a conductive state, with the threshold tunable via the gate voltage. Such current-voltage characteristics can be used, in principle, for implementing radiation-hard all-metallic logic circuits. These results may open new application space for thin films of van der Waals materials.

  19. Application of Single Wall Carbon Nanotubes as Transparent Electrodes in Cu(In,Ga)Se2-Based Solar Cells: Preprint

    SciTech Connect (OSTI)

    Contreras, M.; Barnes, T.; van de Lagemaat, J.; Rumbles, G.; Coutts, T. J.; Weeks, C.; Glatkowski, P.; Levitsky, I.; Peltola, J.

    2006-05-01

    We present a new thin-film solar cell structure in which the traditional transparent conductive oxide electrode (ZnO) is replaced by a transparent conductive coating consisting of a network of bundled single-wall carbon nanotubes. Optical transmission properties of these coatings are presented in relation to their electrical properties (sheet resistance), along with preliminary solar cell results from devices made using CuIn1-xGaxSe2 thin-film absorber materials. Achieving an energy conversion efficiency of >12% and a quantum efficiency of {approx}80% demonstrate the feasibility of the concept. A discussion of the device structures will be presented considering the physical properties of the new electrodes comparing current-voltage results from the new solar cell structure and those from standard ZnO/CdS/Cu(In,Ga)Se2/Mo solar cells.

  20. Population Pulsation Resonances of Excitons in Monolayer MoSe 2 with Sub- 1 ? eV Linewidths

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

    Schaibley, John?R.; Karin, Todd; Yu, Hongyi; Ross, Jason?S.; Rivera, Pasqual; Jones, Aaron?M.; Scott, Marie?E.; Yan, Jiaqiang; Mandrus, D.?G.; Yao, Wang; et al

    2015-04-01

    Monolayer transition metal dichalcogenides, a new class of atomically thin semiconductors, possess optically coupled 2D valley excitons. The nature of exciton relaxation in these systems is currently poorly understood. Here, we investigate exciton relaxation in monolayer MoSe? using polarization-resolved coherent nonlinear optical spectroscopy with high spectral resolution. We report strikingly narrow population pulsation resonances with two different characteristic linewidths of 1 and more »ns. The ultranarrow resonance (« less

  1. Direct imaging of enhanced current collection on grain boundaries of Cu(In,Ga)Se{sub 2} solar cells

    SciTech Connect (OSTI)

    Kim, JunHo; Kim, SeongYeon; Jiang, Chun-Sheng; Ramanathan, Kannan; Al-Jassim, Mowafak M.

    2014-02-10

    We report on direct imaging of current collection by performing conductive atomic force microscopy (C-AFM) measurement on a complete Cu(In,Ga)Se{sub 2} solar cell. The localized current was imaged by milling away the top conductive layer of the device by repeated C-AFM scans. The result exhibits enhanced photocurrent collection on grain boundaries (GBs) of CIGS films, consistent with the argument for electric-field-assisted carrier collection on the GBs.

  2. First demonstration of CdSe as a photocatalyst for hydrogen evolution from water under UV and visible lightw

    E-Print Network [OSTI]

    Osterloh, Frank

    show catalytic activity for photochemical hydrogen evolution from aqueous Na2S/Na2SO3 solution under­10 but can produce H2 from aqueous solutions containing sacrificial electrons donors, such as Na2S and Na2SO3 evolu- tion from water can be achieved with CdSe nanoribbons in the presence of Na2S/Na2SO3

  3. Structural and optical properties of (Ag,Cu)(In,Ga)Se{sub 2} polycrystalline thin film alloys

    SciTech Connect (OSTI)

    Boyle, J. H.; Shafarman, W. N.; Birkmire, R. W.; McCandless, B. E.

    2014-06-14

    The structural and optical properties of pentenary alloy (Ag,Cu)(In,Ga)Se{sub 2} polycrystalline thin films were characterized over the entire compositional range at a fixed (Cu?+?Ag)/(In?+?Ga) ratio. Films deposited at 550?°C on bare and molybdenum coated soda-lime glass by elemental co-evaporation in a single-stage process with constant incident fluxes exhibit single phase chalcopyrite structure, corresponding to 122 spacegroup (I-42d) over the entire compositional space. Unit cell refinement of the diffraction patterns show that increasing Ag substitution for Cu, the refined a{sub o} lattice constant, (Ag,Cu)-Se bond length, and anion displacement increase in accordance with the theoretical model proposed by Jaffe, Wei, and Zunger. However, the refined c{sub o} lattice constant and (In,Ga)-Se bond length deviated from theoretical expectations for films with mid-range Ag and Ga compositions and are attributed to influences from crystallographic bond chain ordering or cation electronegativity. The optical band gap, derived from transmission and reflection measurements, widened with increasing Ag and Ga content, due to influences from anion displacement and cation electronegativity, as expected from theoretical considerations for pseudo-binary chalcopyrite compounds.

  4. Midea: Order (2010-SE-0110, 2012-SE-1402, 2012-SE-1404, 2013-SE-1401) |

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirleyEnergyTher i nAand DOE SafetyofDepartment. "National MidcourseEnergy DOE

  5. Temperature and composition phase diagram in the iron-based ladder compounds Ba 1 - x Cs x Fe 2 Se 3

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

    Hawai, Takafumi; Nambu, Yusuke; Ohgushi, Kenya; Du, Fei; Hirata, Yasuyuki; Avdeev, Maxim; Uwatoko, Yoshiya; Sekine, Yurina; Fukazawa, Hiroshi; Ma, Jie; Chi, Songxue; Ueda, Yutaka; Yoshizawa, Hideki; Sato, Taku J.

    2015-05-01

    We investigated the iron-based ladder compounds (Ba,Cs)Fe?Se?. Their parent compounds BaFe?Se? and CsFe?Se? have different space groups, formal valences of Fe, and magnetic structures. Electrical resistivity, specific heat, magnetic susceptibility, x-ray diffraction, and powder neutron diffraction measurements were conducted to obtain a temperature and composition phase diagram of this system. Block magnetism observed in BaFe?Se? is drastically suppressed with Cs doping. In contrast, stripe magnetism observed in CsFe?Se? is not so fragile against Ba doping. A new type of magnetic structure appears in intermediate compositions, which is similar to stripe magnetism of CsFe?Se?, but interladder spin configuration is different. Intermediate compounds show insulating behavior, nevertheless a finite T-linear contribution in specific heat was obtained at low temperatures.

  6. Temperature and composition phase diagram in the iron-based ladder compounds Ba 1 - x Cs x Fe 2 Se 3

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

    Hawai, Takafumi; Nambu, Yusuke; Ohgushi, Kenya; Du, Fei; Hirata, Yasuyuki; Avdeev, Maxim; Uwatoko, Yoshiya; Sekine, Yurina; Fukazawa, Hiroshi; Ma, Jie; et al

    2015-05-28

    We investigated the iron-based ladder compounds (Ba,Cs)Fe?Se?. Their parent compounds BaFe?Se? and CsFe?Se? have different space groups, formal valences of Fe, and magnetic structures. Electrical resistivity, specific heat, magnetic susceptibility, x-ray diffraction, and powder neutron diffraction measurements were conducted to obtain a temperature and composition phase diagram of this system. Block magnetism observed in BaFe?Se? is drastically suppressed with Cs doping. In contrast, stripe magnetism observed in CsFe?Se? is not so fragile against Ba doping. A new type of magnetic structure appears in intermediate compositions, which is similar to stripe magnetism of CsFe?Se?, but interladder spin configuration is different. Intermediatemore »compounds show insulating behavior, nevertheless a finite T-linear contribution in specific heat was obtained at low temperatures.« less

  7. Photo-crystallization in a-Se layer structures: Effects of film-substrate interface-rigidity

    SciTech Connect (OSTI)

    Lindberg, G. P.; Gross, N.; Weinstein, B. A.; O'Loughlin, T.; Mishchenko, A.; Reznik, A.; Abbaszadeh, S.; Karim, K. S.; Belev, G.

    2014-11-21

    Amorphous selenium (a-Se) films deposited on rigid substrates can undergo photo-induced crystallization (PC) even at temperatures (T) well below the glass transition, T{sub g}???313?K. Substrate-generated shear strain is known to promote the PC process. In the present work, we explore the influence of different substrates (Si and glass), and different film-layer-substrate combinations, on the PC in a variety of a-Se films and film-structures. The intermediate layers (indium tin oxide and polyimide) are chosen to promote conductivity and/or to be a buffer against interface strain in structures of interest for digital imaging applications. The PC characteristics in these samples are evaluated and compared using optical microscopy, atomic-force microscopy, Raman mapping, and T-dependent Raman spectroscopy. Both the presence of a soft intermediate layer, and the thermal softening that occurs for T increasing through T{sub g}, inhibit the tendency for the onset of PC. The extensive PC mapping results in the wide range of samples studied here, as well as the suppression of PC near T{sub g} in this array of samples, strongly support the generality of this behavior. As a consequence, one may expect that the stability of a-Se films against PC can be enhanced by decreasing the rigidity of the film-substrate interface. In this regard, advanced film structures that employ flexible substrates, soft intermediate layers, and/or are designed to be operated near T{sub g} should be explored.

  8. A p ? n transition for Sn-doped Cu(In,Ga)Se{sub 2} bulk materials

    SciTech Connect (OSTI)

    Monsefi, Mehrdad; Kuo, Dong-Hau, E-mail: dhkuo@mail.ntust.edu.tw

    2013-08-15

    Cu(In,Ga)Se{sub 2} (CIGSe) pellets at different Sn contents were fabricated by reactive liquid-phase sintering at 600–700 °C with the help of sintering aids of Sb{sub 2}S{sub 3} and Te. Powder preparation was based upon the molecular formula of Cu{sub 0.9}[(In{sub 0.7?x}Sn{sub x}Ga{sub 0.3}){sub 0.9}Sb{sub 0.1}](S{sub 0.15}Te{sub 0.2}Se{sub 1.65}) or Sn-x-CIGSe. Morphology, structure, and electrical property of Sn-doped CIGSe bulks were investigated. The composition of Sn-doped CIGSe is purposely designed for studying the doping effect on the CIGSe performance. The unexpected increase in hole concentration of CIGSe due to the donor doping is rationalized. A controllable n-type semiconductor is deliberately achieved for Sn-0.15-CIGSe and important for making a p/n homojunction in CIGSe solar cells. - Graphical abstract: The controls in defect type and electrical properties of Cu(In,Ga)Se{sub 2} by doping Sn{sup 4+} on the In{sup 3+} site. Highlights: • n-type Sn-CIGSe with n{sub e} of 6.4×10{sup 16} cm{sup ?3} and ?{sub e} of 2.3 cm{sup 2}/V s was obtained. • This n-type Sn-CIGSe was obtained by material design and composition control. • The reported n-type CIGSe was obtained from the Zn/CIGSe and CdS/CIGSe bilayers. • Extrinsic donor doping was explored through the results of electrical properties. • A n/p homojunction with Sn-CIGSe and undoped one can be used for solar cell devices.

  9. Elastic Scattering Of {sup 6,7}Li+{sup 80}Se At Near And Above Barrier Energies

    SciTech Connect (OSTI)

    Fimiani, L.; Marti, G. V.; Capurro, O. A.; Barbara, E. de; Testoni, J. E.; Zalazar, L.; Arazi, A.; Cardona, M. A.; Carnelli, P.; Figueira, J. M.; Hojman, D.; Martinez Heimann, D.; Negri, A. E.; Pacheco, A. J.; Fernandez Niello, J. O.

    2010-08-04

    In this work we propose to study the elastic scattering of the weakly bound projectiles {sup 6,7}Li on an intermediate mass target {sup 80}Se. From the experimental results presented here, precise angular distributions at energies below, around and above the nominal Coulomb barriers of the systems were obtained. The final goal of our work is to determine the characteristic parameters of the optical potential and use them to address the question of whether the usual threshold anomaly or the breakup threshold anomaly are present or not in these systems.

  10. Enhanced excitonic photoconductivity due to built-in internal electric field in TlGaSe{sub 2} layered semiconductor

    SciTech Connect (OSTI)

    Seyidov, MirHasan Yu. Suleymanov, Rauf A.; ?ale, Yasin; Balaban, Ertan

    2014-12-07

    The strong enhancement, by several orders of magnitude, of the excitonic peak within the photoconductivity spectrum of TlGaSe{sub 2} semiconductor was observed. The samples were polarized in external dc electric field, which was applied prior to the measurements. Due to the accumulation of charges near the surface, an internal electric field was formed. Electron-hole pairs that were created after the absorption of light are fallen in and then separated by the built-in electric field, which prevents radiative recombination process.

  11. 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.

  12. PHYSICAL REVIEW B 83, 125201 (2011) Compositional dependence of structural and electronic properties of Cu2ZnSn(S,Se)4 alloys

    E-Print Network [OSTI]

    Gong, Xingao

    2011-01-01

    on the efficiency of CZTSSe solar cells and explain the high efficiency of the cells with high Se content. DOI: 10: Is there a similar limit to the efficiency as in Cu(In,Ga)Se2 cells, and why is the current highest-efficiency solar properties of Cu2ZnSn(S,Se)4 alloys for thin film solar cells Shiyou Chen,1,2 Aron Walsh,3 Ji-Hui Yang,1 X. G

  13. Predicted roles of defects on band offsets and energetics at CIGS (Cu(In,Ga)Se2/CdS) solar cell interfaces and implications for improving performance

    E-Print Network [OSTI]

    Goddard III, William A.

    Predicted roles of defects on band offsets and energetics at CIGS (Cu(In,Ga)Se2/CdS) solar cell (2014) Predicted roles of defects on band offsets and energetics at CIGS (Cu(In,Ga)Se2/CdS) solar cell ZnO sputtering on the performance of Cu(In,Ga)Se2 thin film solar cells Appl. Phys. Lett. 105, 083906

  14. 1.2 Variedades de curvas. O objetivo desta se,c"ao 'e em primeiro lugar o de especializar alguns resu*

    E-Print Network [OSTI]

    Tausk, Daniel Victor

    - eraliza,c"oes para espa,cos de se,c"oes de um fibrado geral, mas o objetivo des* *ta se,c"ao 'e jus N agora passa a ser chamad* *a de M. Teremos sempre um tipo M de espa,co de se,c"oes que fibrado misto sobre I (cu* *jo fibrado das bases 'e I x M). Teremos ent"ao dois tipos M1, M2 de espa

  15. Performance and Loss Analyses of High-Efficiency CBD-ZnS/Cu(In1-xGax)Se2 Thin-Film Solar Cells

    E-Print Network [OSTI]

    Sites, James R.

    1 Performance and Loss Analyses of High-Efficiency CBD-ZnS/Cu(In1-xGax)Se2 Thin-Film Solar Cells, Setagaya-ku, Tokyo 157-8572, Japan (Received ) KEYWORDS: ZnS buffer, Cu(In,Ga)Se2, thin-film solar cells alternative to CdS in polycrystalline thin-film Cu(In1-xGax)Se2 (CIGS) solar cells. Cells with efficiency

  16. DEVELOPMENT OF A NOVEL PRECURSOR FOR THE PREPARATION BY SELENIZATION OF HIGH EFFICIENCY CuInGaSe2/CdS THIN FILM SOLAR CELLS

    E-Print Network [OSTI]

    Romeo, Alessandro

    /CdS THIN FILM SOLAR CELLS N. Romeo1 , A. Bosio1 , V. Canevari2 , R. Tedeschi1 , S. Sivelli1 , A. Solar cells prepared by depositing in sequence on top of the CuInGaSe2 film 60 nm of CdS, 100 nm of pure(InGa)Se2, Thin Films, Selenization 1 INTRODUCTION CuInGaSe2 based solar cells exhibit the highest

  17. 186 VHDL: LENGUAJE PARA S INTESIS Y MODELADO DE CIRCUITOS c El cronograma correspondiente, como resultado de la simulacion, se muestra en la

    E-Print Network [OSTI]

    Valencia, Universidad de

    â?? on ya se ha introducido en el lavado. vacio: Indica que el tambor estâ?? a vacâ?? �o de agua. lleno: Indica

  18. Density functional theory calculations of the turbostratically disordered compound [(SnSe)1+y]m(VSe2)n

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

    Rudin, Sven P.; Johnson, David C.

    2015-04-30

    Among composite materials that layer constituent substances of nanoscale thicknesses, [(SnSe)1+y ]m(VSe2)n emerges as an example where the constituents retain incommensurate lattice structures. Perpendicular to the stacking direction, the system exhibits random translations and random rotations on average, i.e., turbostratic disorder, with local regions showing twelvefold diffraction patterns. Earlier theoretical work on these structures showed that combining density functional theory with an empirical treatment of the van der Waals interaction gave structural parameters in good agreement with experiment, but no attempt was made to examine the relative orientations. Here we approximate the extended system with one extended constituent and onemore »finite constituent, which allows the treatment of all relative orientations on equal footing. Furthermore, the calculations show how the twelvefold periodicity follows from how the ions of the SnSe layer lock in with favored positions relative to the VSe2 layer, and the associated energy scale supports arguments for the overall turbostratic disorder.« less

  19. Polytypism, polymorphism, and superconductivity in TaSe2–xTex

    SciTech Connect (OSTI)

    Luo, Huixia; Xie, Weiwei; Tao, Jing; Inoue, Hiroyuki; Gyenis, András; Krizan, Jason W.; Yazdani, Ali; Zhu, Yimei; Cava, Robert Joseph

    2015-03-03

    Polymorphism in materials often leads to significantly different physical properties - the rutile and anatase polymorphs of TiO? are a prime example. Polytypism is a special type of polymorphism, occurring in layered materials when the geometry of a repeating structural layer is maintained but the layer stacking sequence of the overall crystal structure can be varied; SiC is an example of a material with many polytypes. Although polymorphs can have radically different physical properties, it is much rarer for polytypism to impact physical properties in a dramatic fashion. Here we study the effects of polytypism and polymorphism on the superconductivity of TaSe?, one of the archetypal members of the large family of layered dichalcogenides. We show that it is possible to access 2 stable polytypes and 2 stable polymorphs in the TaSe2-xTex solid solution, and find that the 3R polytype shows a superconducting transition temperature that is between 6 and 17 times higher than that of the much more commonly found 2H polytype. Thus, the reason for this dramatic change is not apparent, but we propose that it arises either from a remarkable dependence of Tc on subtle differences in the characteristics of the single layers present, or from a surprising effect of the layer stacking sequence on electronic properties that instead are expected to be dominated by the properties of a single layer in materials of this kind.

  20. Visible Light Photoreduction of CO{sub 2} Using CdSe/Pt/TiO{sub 2} Heterostructured Catalysts

    SciTech Connect (OSTI)

    Wang, Congjun; Thompson, Robert L.; Baltrus, John; Matranga, Christopher

    2010-08-01

    A series of CdSe quantum dot (QD)-sensitized TiO{sub 2} heterostructures have been synthesized, characterized, and tested for the photocatalytic reduction of CO{sub 2} in the presence of H{sub 2}O. Our results show that these heterostructured materials are capable of catalyzing the photoreduction of CO{sub 2} using visible light illumination (? > 420 nm) only. The effect of removing surfactant caps from the CdSe QDs by annealing and using a hydrazine chemical treatment have also been investigated. The photocatalytic reduction process is followed using infrared spectroscopy to probe the gas-phase reactants and gas chromatography to detect the products. Gas chromatographic analysis shows that the primary reaction product is CH{sub 4}, with CH{sub 3}OH, H{sub 2}, and CO observed as secondary products. Typical yields of the gas-phase products after visible light illumination (?>420 nm) were 48 ppm g{sup -1} h{sup -1} of CH{sub 4}, 3.3 ppm g{sup -1} h{sup -1} of CH{sub 3}OH (vapor), and trace amounts of CO and H{sub 2}.

  1. Shallow to deep transformation of Se donors in GaSb under hydrostatic pressure H. Navarro-Contreras, F. de Anda-Salazar, and J. Olvera-Hernandez

    E-Print Network [OSTI]

    McCluskey, Matthew

    Shallow to deep transformation of Se donors in GaSb under hydrostatic pressure H. Navarro, although it may be also an indication that the Se shallow donors change to deep donors associated pressures above a certain threshold value. The DX center is a deep-level defect found in many n

  2. [P6Se12]4-: A Phosphorus-Rich Selenophosphate with Low-Valent P In Chung, Angela L. Karst, David P. Weliky, and Mercouri G. Kanatzidis*

    E-Print Network [OSTI]

    Weliky, David

    [P6Se12]4-: A Phosphorus-Rich Selenophosphate with Low-Valent P Centers In Chung, Angela L. Karst, David P. Weliky, and Mercouri G. Kanatzidis* Department of Chemistry, Michigan State UniVersity, East Lansing, Michigan 48824 Received January 19, 2006 The new selenophosphate Rb4P6Se12 features the trans

  3. Proc. of the 24th IEEE Photovoltaic Specialists Conference (IEEE, New York, 1995), pp. 291-294. ADMITTANCE MEASUREMENTS ON Cu(In,Ga)Se2 POLYCRYSTALLINE THIN-

    E-Print Network [OSTI]

    Scofield, John H.

    for approximately 30 CIS and CIGS polycrystalline thin film solar cells having efficiencies of 12% or better-294. ADMITTANCE MEASUREMENTS ON Cu(In,Ga)Se2 POLYCRYSTALLINE THIN- FILM SOLAR CELLS John H. Scofield Physics-16.4% efficient, 0.43 cm2 area, polycrystalline, thin-film solar cells solar cells from 16 different CuInSe2 (CIS

  4. Z .Thin Solid Films 372 2000 212 217 Z .Na in selenized Cu In,Ga Se on Na-containing and Na-free2

    E-Print Network [OSTI]

    Rockett, Angus

    of the substrate glass on standard Z . Z .production Cu In Ga Se CIGS -based solar cells fabricated by selenization; Selenides2 1. Introduction Z .Production of large quantities of Cu In Ga Se1yx x 2 Z . Z .CIGS -based solar solar cell performance. Impurities, both U Corresponding author. Tel.: q1-217-333-0417; fax: q1

  5. Automi e Linguaggi Formali { A.A. 2013/2014 1. Dire se esiste un algoritmo (che termini in tempo nito) che, dato in

    E-Print Network [OSTI]

    Rossi, Francesca

    Automi e Linguaggi Formali { A.A. 2013/2014 Homework 7 22.11.2013 1. Dire se esiste un algoritmo ferma per la stringa ab 2. Dire se esiste un algoritmo (che termini in tempo #12;nito) che, dato

  6. Automi e Linguaggi Formali A.A. 2011/2012 1. Dire se esiste un algoritmo (che termini in tempo finito) che, dato in

    E-Print Network [OSTI]

    Rossi, Francesca

    Automi e Linguaggi Formali ­ A.A. 2011/2012 Homework 7 24.11.2011 1. Dire se esiste un algoritmo ferma per la stringa ab 2. Dire se esiste un algoritmo (che termini in tempo finito) che, dato in input

  7. 22nd European Photovoltaic Solar Energy Conference, Milan, 3-7 September 2007 Cu(InGa)Se2 THIN-FILM SOLAR CELLS

    E-Print Network [OSTI]

    22nd European Photovoltaic Solar Energy Conference, Milan, 3-7 September 2007 Cu(InGa)Se2 THIN-FILM INTRODUCTION Cu(InGa)Se2-based thin-film solar cells have high conversion-efficiencies (the laboratory record

  8. Enhanced Performance of CdS/CdSe Quantum Dot Cosensitized Solar Cells via Homogeneous Distribution of Quantum Dots in TiO2

    E-Print Network [OSTI]

    Cao, Guozhong

    , simply increasing film thickness did not make significant contribution to improving solar cell efficiencyEnhanced Performance of CdS/CdSe Quantum Dot Cosensitized Solar Cells via Homogeneous Distribution cosensitized solar cells. The CdS and CdSe quantum dots were prepared on TiO2 mesoporous film through

  9. Sanders, J. E.; and Merguerian, Charles, 1992a, Directional history of Pleistocene glaciers inferred from features eroded on bedrock, New York metropolitan area, SE NY.

    E-Print Network [OSTI]

    Merguerian, Charles

    inferred from features eroded on bedrock, New York metropolitan area, SE NY. If a glacier erodes bedrock Tryon Park, Central Park, and in the New York Botanical Garden. To Cite This Abstract: Sanders, J. E on bedrock, New York metropolitan area, SE NY (abs.): Geological Society of America, Abstracts with Programs

  10. Conflicting structural and geochronological data from the Ibituruna quartz-syenite (SE Brazil): Effect of protracted "hot" orogeny and slow cooling rate?

    E-Print Network [OSTI]

    Cattin, Rodolphe

    Conflicting structural and geochronological data from the Ibituruna quartz-syenite (SE Brazil-Pb and 40Ar-39Ar geochronology Slow cooling rate SE-Brazil neoproterozoic orogeny The Ibituruna quartz-rock. Unexpectedly, geochronological data suggest a rather different conclusion. LA-ICP-MS and SHRIMP ages of zircons

  11. Structural investigation on Ge{sub x}Sb{sub 10}Se{sub 90?x} glasses using x-ray photoelectron spectra

    SciTech Connect (OSTI)

    Wei, Wen-Hou [Centre for Ultrahigh Bandwidth Devices for Optical Systems (CUDOS), Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Department of Applied Physics, Chongqing University, Chongqing 401331 (China); Xiang, Shen [College of Information Science and Engineering, Ningbo University, Ningbo 315211 (China); Xu, Si-Wei; Wang, Rong-Ping, E-mail: rongping.wang@anu.edu.au [Centre for Ultrahigh Bandwidth Devices for Optical Systems (CUDOS), Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Fang, Liang [Department of Applied Physics, Chongqing University, Chongqing 401331 (China)

    2014-05-14

    The structure of Ge{sub x}Sb{sub 10}Se{sub 90?x} glasses (x?=?7.5, 10, 15, 20, 25, 27.5, 30, and 32.5 at. %) has been investigated by x-ray photoelectron spectroscopy (XPS). Different structural units have been extracted and characterized by decomposing XPS core level spectra, the evolution of the relative concentration of each structural unit indicates that, the relative contributions of Se-trimers and Se-Se-Ge(Sb) structure decrease with increasing Ge content until they become zero at chemically stoichiometric glasses of Ge{sub 25}Sb{sub 10}Se{sub 65}, and then the homopolar bonds like Ge-Ge and Sb-Sb begin to appear in the spectra. Increase of homopolar bonds will extend band-tails into the gap and narrow the optical band gap. Thus, the glass with a stoichiometric composition generally has fewer defective bonds and larger optical bandgap.

  12. NMR characterization of sulphur substitution effects in the KxFe2-ySe2-zSz high-Tc superconductor

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

    Torchetti, D. A.; Imai, T.; Lei, H. C.; Petrovic, C.

    2012-04-01

    We present a?? Se NMR study of the effect of S substitution in the high-Tc superconductor KxFe2-ySe2-zSz in a temperature range up to 250 K. We examine two S concentrations, with z=0.8 (Tc~ 26 K) and z=1.6 (nonsuperconducting). The samples containing sulphur exhibit broader NMR line shapes than the KxFe?Se? sample due to local disorder in the Se environment. Our Knight shift ??K data indicate that in all samples, uniform spin susceptibility decreases with temperature, and that the magnitude of the Knight shift itself decreases with increased S concentration. In addition, S substitution progressively suppresses low-frequency spin fluctuations. None ofmore »the samples exhibit an enhancement of low-frequency antiferromagnetic spin fluctuations near Tc in 1/T?T, as seen in FeSe.« less

  13. Temperature-dependent carrier–phonon coupling in topological insulator Bi{sub 2}Se{sub 3}

    SciTech Connect (OSTI)

    Lai, Yi-Ping; Liu, Jia-Ming; Chen, Hsueh-Ju; Wu, Kuang-Hsiung

    2014-12-08

    Temperature-dependent (11.0?K?294.5?K) carrier–phonon coupling in Bi{sub 2}Se{sub 3} is investigated by ultrafast pump?probe spectroscopy. The rise time of the differential reflectivity is interpreted by a combined effect of electron temperature relaxation and hot-phonon lifetime. The electron?phonon coupling constant of the bulk state (?=0.63±0.05) is deduced from theoretical fitting. Increasing hot-phonon lifetime with decreasing temperature is attributed to a decreasing phonon?phonon collision rate. A complete analysis of the thermalization process is presented. Understanding carrier and phonon dynamics is essential for future optoelectronic and spintronic applications of topological insulators.

  14. Insulating and metallic spin glass in Ni-doped KxFe2-ySe? single crystals

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

    Ryu, Hyejin; Abeykoon, Milinda; Wang, Kefeng; Lei, Hechang; Lazarevic, N.; Warren, J. B.; Bozin, E. S.; Popovic, Z. V.; Petrovic, C.

    2015-05-04

    We report electron doping effects by Ni in KxFe2-?-yNiySe? (0.06 ? y ? 1.44) single crystal alloys. A rich ground state phase diagram is observed. A small amount of Ni (~ 4%) suppressed superconductivity below 1.8 K, inducing insulating spin glass magnetic ground state for higher Ni content. With further Ni substitution, metallic resistivity is restored. For high Ni concentration in the lattice the unit cell symmetry is high symmetry I4/mmm with no phase separation whereas both I4/m + I4/mmm space groups were detected in the phase separated crystals when concentration of Ni more »with the absence of crystalline Fe vacancy order.« less

  15. Nuclear Structure Relevant to Neutrinoless Double Beta Decay: the Valence Protons in 76Ge and 76Se

    E-Print Network [OSTI]

    B. P. Kay; J. P. Schiffer; S. J. Freeman; T. Adachi; J. A. Clark; C. M. Deibel; H. Fujita; Y. Fujita; P. Grabmayr; K. Hatanaka; D. Ishikawa; H. Matsubara; Y. Meada; H. Okamura; K. E. Rehm; Y. Sakemi; Y. Shimizu; H. Shimoda; K. Suda; Y. Tameshige; A. Tamii; C. Wrede

    2008-10-22

    The possibility of observing neutrinoless double beta decay offers the opportunity of determining the effective neutrino mass if the nuclear matrix element were known. Theoretical calculations are uncertain and the occupations of valence orbits by nucleons active in the decay are likely to be important. The occupation of valence proton orbits in the ground states of 76Ge, a candidate for such decay, and 76Se, the corresponding daughter nucleus, were determined by precisely measuring cross sections for proton-removing transfer reactions. As in previous work on neutron occupations, we find that the Fermi surface for protons is much more diffuse than previously thought, and the occupancies of at least three orbits change significantly between the two 0+ ground states.

  16. Nuclear structure relevant to neutrinoless double {beta} decay : the valence protons in {sup 76}Ge and {sup 76}Se.

    SciTech Connect (OSTI)

    Kay, B. P.; Schiffer, J. P.; Freeman, S. J.; Adachi, T.; Clark, J. A.; Deibel, C. M.; Fujita, H.; Fujita, Y.; Grabmayr, P.; Hatanaka, K.; Ishikawa, D.; Matsubara, H.; Meada, Y.; Okamura, H.; Rehm, K. E.; Sakemi, T.; Shimizu, Y.; Shimoda, H.; Suda, K.; Tameshige, Y.; Tamii, A.; Wrede, C.; Univ. of Manchester; Osaka Univ.; Yale Univ.; Univ. of Tuebingen; Miyazaki Univ.; Tohoku Univ.; Univ. of Tokyo; Kyushu Univ.

    2009-01-01

    The possibility of observing neutrinoless double {beta} decay offers the opportunity of determining the effective neutrino mass if the nuclear matrix element were known. Theoretical calculations are uncertain, and the occupation of valence orbits by nucleons active in the decay is likely to be important. The occupation of valence proton orbits in the ground states of {sup 76}Ge, a candidate for such decay, and {sup 76}Se, the corresponding daughter nucleus, is determined by precisely measuring cross sections for proton-removing transfer reactions. As in previous work on neutron occupation, we find that the Fermi surface for protons is much more diffuse than previously thought, and the occupancies of at least three orbits change significantly between the two 0{sup +} ground states.

  17. Nuclear structure relevant to neutrinoless double {beta} decay: The valence protons in {sup 76}Ge and {sup 76}Se

    SciTech Connect (OSTI)

    Kay, B. P.; Schiffer, J. P.; Rehm, K. E. [Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Freeman, S. J. [University of Manchester, Manchester M13 9PL (United Kingdom); Adachi, T.; Fujita, H.; Hatanaka, K.; Ishikawa, D.; Matsubara, H.; Okamura, H.; Suda, K.; Tameshige, Y.; Tamii, A. [Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Clark, J. A.; Deibel, C. M.; Wrede, C. [Yale University, New Haven, Connecticut 06520 (United States); Fujita, Y. [Department of Physics, Osaka University, Toyonaka, Osaka 567-0043 (Japan); Grabmayr, P. [Physikalisches Institut, Universitaet Tuebingen, D-72076 Tuebingen (Germany); Meada, Y. [Department of Applied Physics, Miyazaki University, Miyazaki 889-2192 (Japan); Sakemi, Y. [Cyclotron Radioisotope Center, Tohoku University, Sendai, Miyagi 980-8578 (Japan)] (and others)

    2009-02-15

    The possibility of observing neutrinoless double {beta} decay offers the opportunity of determining the effective neutrino mass if the nuclear matrix element were known. Theoretical calculations are uncertain, and the occupation of valence orbits by nucleons active in the decay is likely to be important. The occupation of valence proton orbits in the ground states of {sup 76}Ge, a candidate for such decay, and {sup 76}Se, the corresponding daughter nucleus, is determined by precisely measuring cross sections for proton-removing transfer reactions. As in previous work on neutron occupation, we find that the Fermi surface for protons is much more diffuse than previously thought, and the occupancies of at least three orbits change significantly between the two 0{sup +} ground states.

  18. Insulating and metallic spin glass in Ni-doped K x Fe 2 - y Se 2 single crystals

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

    Ryu, Hyejin; Abeykoon, Milinda; Wang, Kefeng; Lei, Hechang; Lazarevic, N.; Warren, J. B.; Bozin, E. S.; Popovic, Z. V.; Petrovic, C.

    2015-05-01

    We report electron doping effects by Ni in KxFe2-?-yNiySe?(0.06?y?1.44) single-crystal alloys. A rich ground-state phase diagram is observed. A small amount of Ni (~4%) suppressed superconductivity below 1.8 K, inducing insulating spin-glass magnetic ground state for higher Ni content. With further Ni substitution, metallic resistivity is restored. For high Ni concentration in the lattice the unit cell symmetry is high symmetry I4/mmm with no phase separation whereas both I4/m+I4/mmm space groups were detected in the phase separated crystals when concentration of Ni < Fe. The absence of superconductivity coincides with the absence of crystalline Fe vacancy order.

  19. Influence of defects on the charge density wave of ([SnSe]1+?)1(VSe2)1 ferecrystals

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

    Falmbigl, Matthias; Putzky, Daniel; Ditto, Jeffrey; Esters, Marco; Bauers, Sage R.; Ronning, Filip; Johnson, David C.

    2015-07-14

    A series of ferecrystalline compounds ([SnSe]1+?)1(VSe2)1 with varying Sn/V ratios were synthesized using the modulated elemental reactant technique. Temperature-dependent specific heat data reveal a phase transition at 102 K, where the heat capacity changes abruptly. An abrupt increase in electrical resistivity occurs at the same temperature, correlated with an abrupt increase in the Hall coefficient. Combined with the magnitude and nature of the specific heat discontinuity, this suggests that the transition is similar to the charge density wave transitions in transition metal dichalcogenides. An ordered intergrowth was formed over a surprisingly wide compositional range of Sn/V ratios of 0.89 ?more »1 + ? ? 1.37. X-ray diffraction and transmission electron microscopy reveal the formation of various volume defects in the compounds in response to the nonstoichiometry. The electrical resistivity and Hall coefficient data of samples with different Sn/V ratios show systematic variation in the carrier concentration with the Sn/V ratio. There is no significant change in the onset temperature of the charge density wave transition, only a variation in the carrier densities before and after the transition. Given the sensitivity of the charge density wave transitions of transition metal dichalcogenides to variations in composition, it is very surprising that the charge density wave transition observed at 102 K for ([SnSe]1.15)1(VSe2)1 is barely influenced by the nonstoichiometry and structural defects. As a result, this might be a consequence of the two-dimensional nature of the structurally independent VSe2 layers.« less

  20. Characterization of few-layer 1T-MoSe{sub 2} and its superior performance in the visible-light induced hydrogen evolution reaction

    SciTech Connect (OSTI)

    Gupta, Uttam; Naidu, B. S.; Maitra, Urmimala; Rao, C. N. R.; Singh, Anjali; Shirodkar, Sharmila N.; Waghmare, Umesh V.

    2014-09-01

    Based on earlier results on the photocatalytic properties of MoS{sub 2}, the 1T form of MoSe{sub 2}, prepared by lithium intercalation and exfoliation of bulk MoSe{sub 2}, has been employed for the visible-light induced generation of hydrogen. 1T-MoSe{sub 2} is found to be superior to both 2H and 1T MoS{sub 2} as well as 2H-MoSe{sub 2} in producing hydrogen from water, the yield being in the 60–75 mmol?h{sup ?1}?g{sup ?1} range with a turn over frequency of 15–19 h{sup ?1}. First principles calculations reveal that 1T-MoSe{sub 2} has a lower work function than 2H-MoSe{sub 2} as well as 1T and 2H-MoS{sub 2}, making it easier to transfer an electron from 1T-MoSe{sub 2} for the production of H{sub 2}.

  1. Effect of argon gas flow rate on properties of film electrodes prepared by thermal vacuum evaporation from synthesized Cu{sub 2}SnSe{sub 3} source

    SciTech Connect (OSTI)

    Sabli, Nordin; Talib, Zainal Abidin; Yunus, Wan Mahmood Mat [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang (Malaysia); Zainal, Zulkarnain [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang (Malaysia); Hilal, Hikmat S. [SSERL, Department of Chemistry An-Najah N. University, PO Box 7, Nablus, West Bank (Country Unknown); Fujii, Masatoshi [Department of Molecular Science, School of Medicine, Shimane University, Izumo, Shimane, 693-8501 (Japan)

    2014-03-05

    This work describes a new technique to enhance photoresponse of metal chalcogenide-based semiconductor film electrodes deposited by thermal vacuum evaporation under argon gas flow from synthesized Cu{sub 2}SnSe{sub 3} sources. SnSe formation with Cu-doped was obtained under higher argon gas flow rate (V{sub A} = 25 cm{sup 3}/min). Higher value of photoresponse was observed for films deposited under V{sub A} = 25 cm{sup 3}/min which was 9.1%. This finding indicates that Cu atoms inside the SnSe film were important to increase carrier concentrations that promote higher photoresponse.

  2. Wideband saturable absorption in few-layer molybdenum diselenide (MoSe2) for Q-switching Yb-, Er- and Tm-doped fiber lasers

    E-Print Network [OSTI]

    Woodward, R. I.; Howe, R. C. T.; Runcorn, T. H.; Hu, G.; Torrisi, F.; Kelleher, E. J. R.; Hasan, T.

    2015-06-23

    nm) gap for monolayer MoSe2 [30, 35]. The nonlinear optical properties of few-layer MoSe2 have been studied by Wang et al. for UALPE MoSe2 dispersed in cyclo- hexylpyrrolidone (CHP) [11], and by Dong et al. in N-methyl-pyrrolidone (NMP) [36]; both... than considering only the surface energies or Hildebrand solubility pa- rameters of the solvents and materials [40, 41]. Experimental evidence suggests that NMP and CHP are two of the more suitable solvents for TMDs [41]. However, it is challenging...

  3. Electron-beam induced variation of surface profile in amorphous As{sub 20}Se{sub 80} films

    SciTech Connect (OSTI)

    Kaganovskii, Yu. E-mail: trunov.m@gmail.com; Trunov, M. L. E-mail: trunov.m@gmail.com; Cserhati, C.; Beke, D. L.; Kökényesi, S.

    2014-05-14

    Unusual profile variation of holographic surface relief gratings is detected in thin (2??m) As{sub 20}Se{sub 80} chalcogenide films under e-beam irradiation: gratings of small periods were smoothed, whereas the gratings of larger periods increased their amplitudes. Irradiation was carried out in SEM, with 20?kV voltage and 8?nA current; the profiles of the irradiated areas were analyzed both by AFM and SEM. It is found that the kinetics of both flattening and growth followed by exponential law and took place due to lateral mass transport accelerated by e-irradiation. It is shown that the profile variation is mainly caused by competition between capillary forces and “chemical” forces induced by broken and deformed atomic bonds under e-beam irradiation. The kinetics of profile variation was calculated assuming that the mechanism of e-beam induced mass transfer is volume diffusion. The diffusion coefficients were estimated from the experimental data using theoretical expressions derived.

  4. 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.

  5. Temperature-driven band inversion in Pb0.77Sn0.23Se: Optical and Hall effect studies

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

    Anand, Naween; Buvaev, Sanal; Hebard, A. F.; Tanner, D. B.; Chen, Zhiguo; Li, Zhiqiang; Choudhary, Kamal; Sinnott, S. B.; Gu, Genda; Martin, C.

    2014-12-23

    Optical and Hall-effect measurements have been performed on single crystals of Pb?.??Sn?.??Se, a IV-VI mixed chalcogenide. The temperature dependent (10–300 K) reflectance was measured over 40–7000 cm?¹ (5–870 meV) with an extension to 15,500 cm?¹ (1.92 eV) at room temperature. The reflectance was fit to the Drude-Lorentz model using a single Drude component and several Lorentz oscillators. The optical properties at the measured temperatures were estimated via Kramers-Kronig analysis as well as by the Drude-Lorentz fit. The carriers were p-type with the carrier density determined by Hall measurements. A signature of valence intraband transition is found in the low-energy opticalmore »spectra. It is found that the valence-conduction band transition energy as well as the free carrier effective mass reach minimum values at 100 K, suggesting temperature-driven band inversion in the material. Thus, density function theory calculation for the electronic band structure also make similar predictions.« less

  6. Emergence of coherence in the charge-density wave state of 2H-NbSe2

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

    Chatterjee, U.; Zhao, J.; Iavarone, M.; Di Capua, R.; Castellan, J. P.; Karapetrov, G.; Malliakas, C. D.; Kanatzidis, M. G.; Claus, H.; Ruff, J. P. C.; et al

    2015-02-17

    A charge-density wave (CDW) state has a broken symmetry described by a complex order parameter with an amplitude and a phase. The conventional view, based on clean, weak-coupling systems, is that a finite amplitude and long-range phase coherence set in simultaneously at the CDW transition temperature Tcdw. Here we investigate, using photoemission, X-ray scattering and scanning tunnelling microscopy, the canonical CDW compound 2H-NbSe2 intercalated with Mn and Co, and show that the conventional view is untenable. We find that, either at high temperature or at large intercalation, CDW order becomes short-ranged with a well-defined amplitude, which has impacts on themore »electronic dispersion, giving rise to an energy gap. The phase transition at Tcdw marks the onset of long-range order with global phase coherence, leading to sharp electronic excitations. Our observations emphasize the importance of phase fluctuations in strongly coupled CDW systems and provide insights into the significance of phase incoherence in ‘pseudogap’ states.« less

  7. 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 [Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373-1, Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Yang, Heesun [Department of Materials Science and Engineering, Hongik University, 72-1, Sangsu-dong, Mapo-gu, Seoul 121-791 (Korea, Republic of)

    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.

  8. Uso de Desinfectantes en Programas de Limpieza Verde Los desinfectantes y sanitizantes se usan en la mayora de programas de limpieza. Los desinfectantes

    E-Print Network [OSTI]

    Oliver, Douglas L.

    ser enjuagados con agua. Lo mismo sucede cuando te lavas las manos con jabón y agua o cuando lavas instrucciones en la etiqueta. Si usas un concentrado, asegúrate que se mezcle el químico con la cantidad de agua

  9. Photo-Activated Luminescence of CdSe Quantum Dot Monolayers S. R. Cordero, P. J. Carson, R. A. Estabrook, G. F. Strouse, and S. K. Buratto*

    E-Print Network [OSTI]

    Photo-Activated Luminescence of CdSe Quantum Dot Monolayers S. R. Cordero, P. J. Carson, R. A passivation is even more critical in quantum dot solids where inter-dot coupling reduces the QY of the film

  10. Atomic and electronic structures of single-layer FeSe on SrTiO3(001): The role of oxygen deficiency

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

    Bang, Junhyeok; Li, Zhi; Sun, Y. Y.; Samanta, Amit; Zhang, Y. Y.; Zhang, Wenhao; Wang, Lili; Chen, X.; Ma, Xucun; Xue, Q.-K.; et al

    2013-06-06

    Using first-principles calculation, we propose an interface structure for single triple-layer FeSe on the SrTiO3(001) surface, a high-Tc superconductor found recently. The key component of this structure is the oxygen deficiency on the top layer of the SrTiO3 substrate, as a result of Se etching used in preparing the high-Tc samples. The O vacancies strongly bind the FeSe triple layer to the substrate giving rise to a (2×1) reconstruction, as observed by scanning tunneling microscopy. The enhanced binding correlates to the significant increase of Tc observed in experiment. The O vacancies also serve as the source of electron doping, whichmore »modifies the Fermi surface of the first FeSe layer by filling the hole pocket near the center of the surface Brillouin zone, as suggested from angle-resolved photoemission spectroscopy measurement.« less

  11. Limitation of the Open-Circuit Voltage Due to Metastable Intrinsic Defects in Cu(In,Ga)Se2 and Strategies to Avoid These Defects: Preprint

    SciTech Connect (OSTI)

    Lany, S.; Zunger, A.

    2008-05-01

    This paper summarizes using first-principles defect theory to investigate the role of intrinsic point defects in the limitation of the open-circuit voltage (VOC) in Cu(In,Ga)Se2 solar cells.

  12. ZnO/ZnS(O,OH)/Cu(In,Ga)Se2/Mo SOLAR CELL WITH 18.6% EFFICIENCY M.A. Contreras, 2

    E-Print Network [OSTI]

    Sites, James R.

    ZnO/ZnS(O,OH)/Cu(In,Ga)Se2/Mo SOLAR CELL WITH 18.6% EFFICIENCY 1 M.A. Contreras, 2 T. Nakada, 2 M analysis between this type of solar cell and the slightly more efficient ZnO/CdS/Cu(In,Ga)Se2/Mo solar cell for conversion efficiency above 20% in thin-film polycrystalline solar cells. It quantifies the gains in current

  13. Oceanography | Vol. 25, No.162 O C E AN I C SPR E A D I N G C ENT E R PRO C E S SE S |

    E-Print Network [OSTI]

    Girguis, Peter R.

    Oceanography | Vol. 25, No.162 O C E AN I C SPR E A D I N G C ENT E R PRO C E S SE S | Ridge 2000 PRO G R A M R E SE A RCH Oceanography | Vol. 25, No.162 Links from Mantle to Microbe at the Lau that dominate biomass in this vent system. #12;Oceanography | March 2012 63 includes water, which has a major e

  14. F589 -TERCEIRA LISTA DE EXCERCICIOS 1. Ilumina-se uma superficie de aluminio com luz de comprimento de onda 2000A. No

    E-Print Network [OSTI]

    de Aguiar, Marcus A. M.

    F589 - TERCEIRA LISTA DE EXCERC´ICIOS 1. Ilumina-se uma superf´icie de alum´inio com luz de^encia de corte para o alum´inio? (e) Se a intensidade da luz incidente for 2.0 W/m2 qual o n´umero m corta para foto-el´etrons emitidos por uma superf´icie iluminada por luz com = 4910 °A ´e 0.71V

  15. ALERTCO RF/RFID 217 NEW BRIGHTON LANE SE, CALGARY, ALBERTA CANADA T2Z 0E3 (403) 719-6249

    E-Print Network [OSTI]

    ALERTCO RF/RFID 217 NEW BRIGHTON LANE SE, CALGARY, ALBERTA CANADA T2Z 0E3 (403) 719, ALBERTA CANADA T2Z 0E3 (403) 719-6249 This document may only be copied in its entirety, in original form......................................................................................................................... 17 #12;ALERTCO RF/RFID 217 NEW BRIGHTON LANE SE, CALGARY, ALBERTA CANADA T2Z 0E3 (403) 719

  16. The influence of air temperature inversions on snowmelt and glacier mass-balance simulations, Ammassalik island, SE Greenland

    SciTech Connect (OSTI)

    Mernild, Sebastian Haugard [Los Alamos National Laboratory; Liston, Glen [COLORADO STATE UNIV.

    2009-01-01

    In many applications, a realistic description of air temperature inversions is essential for accurate snow and glacier ice melt, and glacier mass-balance simulations. A physically based snow-evolution modeling system (SnowModel) was used to simulate eight years (1998/99 to 2005/06) of snow accumulation and snow and glacier ice ablation from numerous small coastal marginal glaciers on the SW-part of Ammassalik Island in SE Greenland. These glaciers are regularly influenced by inversions and sea breezes associated with the adjacent relatively low temperature and frequently ice-choked fjords and ocean. To account for the influence of these inversions on the spatiotemporal variation of air temperature and snow and glacier melt rates, temperature inversion routines were added to MircoMet, the meteorological distribution sub-model used in SnowModel. The inversions were observed and modeled to occur during 84% of the simulation period. Modeled inversions were defined not to occur during days with strong winds and high precipitation rates due to the potential of inversion break-up. Field observations showed inversions to extend from sea level to approximately 300 m a.s.l., and this inversion level was prescribed in the model simulations. Simulations with and without the inversion routines were compared. The inversion model produced air temperature distributions with warmer lower elevation areas and cooler higher elevation areas than without inversion routines due to the use of cold sea-breeze base temperature data from underneath the inversion. This yielded an up to 2 weeks earlier snowmelt in the lower areas and up to 1 to 3 weeks later snowmelt in the higher elevation areas of the simulation domain. Averaged mean annual modeled surface mass-balance for all glaciers (mainly located above the inversion layer) was -720 {+-} 620 mm w.eq. y{sup -1} for inversion simulations, and -880 {+-} 620 mm w.eq. y{sup -1} without the inversion routines, a difference of 160 mm w.eq. y{sup -1}. The annual glacier loss for the two simulations was 50.7 x 10{sup 6} m{sup 3} y{sup -1} and 64.4 x 10{sup 6} m{sup 3} y{sup -1} for all glaciers - a difference of {approx}21%. The average equilibrium line altitude (ELA) for all glaciers in the simulation domain was located at 875 m a.s.l. and at 900 m a.s.l. for simulations with or without inversion routines, respectively.

  17. sHOrT COMMUniCATiOns 3838 SEX-ROLE REVERSAL IN SONG? FEMALES SING MORE FREQUENTLY THAN MALES

    E-Print Network [OSTI]

    Murphy, Troy G.

    not be unique. Key words: Bird song, female song, Icterus pustulatus, trop- ical songbird, sexual selection Department of Biology, Queen's University, Kingston, Ontario K7L 6, anada Abstract. Birds in which both sexes female song in other sexu- ally monomorphic or weakly dimorphic species, so such patterns might

  18. I think that I shall never see {hor_ellipsis} a lovely forestry policy: Land use programs for conservation of forests

    SciTech Connect (OSTI)

    Rayner, S.F.; Richards, K.R.

    1994-01-01

    Forestry programs are frequently invoked as having potential for mitigation of greenhouse gas emissions. Most studies have attempted to quantify the potential impact of forest programs on carbon uptake and the potential costs of such programs. In this paper, we will attempt instead to focus on the institutional issues of the implementation of forestry programs for carbon sequestration. In particular, we explore the challenges for implementing forest programs that are: of increasing technological complexity; and in settings that depart significantly from the idealized conditions of economic models. We start in Section 1 by examining a suite of instruments that are commonly employed to implement a given policy. Section 2 examines a relatively simple case -- a tree-planting program in the US -- and demonstrates that there are significant difficulties involved in implementing a carbon sequestration program, even in a well-developed market economy. Section 3 focuses on other technologies in the US and why the choice of policy instruments and program design is more difficult than for the simple tree-planting case. Section 4 considers implementation of forestry policies in other countries where the economies may bear less resemblance to the ideal market economy than the US. In those settings, the choice of policy instruments may be very sensitive to non-market considerations that are often missed in conventional policy and cost analysis.

  19. Correlation between morphology, chemical environment, and ferromagnetism in the intrinsic-vacancy dilute magnetic semiconductor Cr-doped Ga2Se3/Si(001)

    SciTech Connect (OSTI)

    Yitamben, E.N.; Arena, D.; Lovejoy, T.C.; Pakhomov, A.B.; Heald, S.M.; Negusse, E.; Ohuchi, F.S.; Olmstead, M.A.

    2011-01-28

    Chromium-doped gallium sesquiselenide, Cr:Ga{sub 2}Se{sub 3}, is a member of a new class of dilute magnetic semiconductors exploiting intrinsic vacancies in the host material. The correlation among room-temperature ferromagnetism, surface morphology, electronic structure, chromium concentration, and local chemical and structural environments in Cr:Ga{sub 2}Se{sub 3} films grown epitaxially on silicon is investigated with magnetometry, scanning tunneling microscopy, photoemission spectroscopy, and x-ray absorption spectroscopy. Inclusion of a few percent chromium in Ga{sub 2}Se{sub 3} results in laminar, semiconducting films that are ferromagnetic at room temperature with a magnetic moment 4{micro}{sub B}/Cr. The intrinsic-vacancy structure of defected-zinc-blende {beta}-Ga{sub 2}Se{sub 3} enables Cr incorporation in a locally octahedral site without disrupting long-range order, determined by x-ray absorption spectroscopy, as well as strong overlap between Cr 3d states and the Se 4p states lining the intrinsic-vacancy rows, observed with photoemission. The highest magnetic moment per Cr is observed near the solubility limit of roughly one Cr per three vacancies. At higher Cr concentrations, islanded, metallic films result, with a magnetic moment that depends strongly on surface morphology. The effective valence is Cr{sup 3+} in laminar films, with introduction of Cr{sup 0} upon islanding. A mechanism is proposed for laminar films whereby ordered intrinsic vacancies mediate ferromagnetism.

  20. 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

  1. Effect of sintering in ball-milled K{sub 2}Bi{sub 8}Se{sub 13} thermoelectric nano-composites

    SciTech Connect (OSTI)

    Hatzikraniotis, E.; Ioannou, M.; Chrissafis, K.; Chung, D.Y.; Paraskevopoulos, K.M.; Kyratsi, Th.

    2012-09-15

    K{sub 2}Bi{sub 8}Se{sub 13} has many attractive features for thermoelectric applications. Recently, K{sub 2}Bi{sub 8}Se{sub 13}-based nanocomposite materials, consisting of nano-crystalline, micro-crystalline and amorphous phases, have been fabricated based on powder technology techniques. The Seebeck coefficient has been enhanced while the thermal conductivity has been decreased presenting, thus, interesting behavior. The behavior of the materials under heat treatment conditions is now of interest, as the application of sintering process is necessary for the development of thermoelectric modules. In this work, the crystallization of the K{sub 2}Bi{sub 8}Se{sub 13}-based nano-composites is studied using Differential Scanning Calorimetry. The results show that crystallization follows a multiple-step process with different activation energies. The thermoelectric properties are also discussed in the range that crystallization occurs. - Graphical Abstract: {beta}-K{sub 2}Bi{sub 8}Se{sub 13}-based nanocomposites follow a multiple-step crystallization process. Highlights: Black-Right-Pointing-Pointer K{sub 2}Bi{sub 8}Se{sub 13}-based composites consisting of nanocrystalline and amorphous phases. Black-Right-Pointing-Pointer Sintering results multiple-step crystallization with variable activation energies. Black-Right-Pointing-Pointer Thermoelectric properties follow a step-like behavior during sintering. Black-Right-Pointing-Pointer Properties are attributed to the strain relaxation, nucleation and grain growth.

  2. Polycrystalline CuInSe{sub 2} and CdTe solar cells. Annual subcontract report, April 15, 1992--April 14, 1993

    SciTech Connect (OSTI)

    Dhere, N.G. [Florida Solar Energy Center, Cape Canaveral, FL (United States)

    1994-08-01

    The principal objective of the research project is to develop processes for the fabrication of cadmium-telluride, CdTe, and copper-indium-gallium-diselenide, Cu(In{sub 1{minus}x}Ga{sub x})Se{sub 2}, polycrystalline-thin-film solar cells using techniques that can be scaled-up for economic manufacture on a large scale. The aims are to fabricate CdTe solar cells using Cd and Te layers sputtered from elemental targets; to promote the interdiffusion between Cd/Te layers, CdTe phase formation, and grain growth; to utilize non-toxic selenization so as to avoid the use of extremely toxic H{sub 2}Se in the fabrication of Cu(In{sub l{minus}x}Ga{sub x})Se{sub 2} thin-film solar cells; to optimize selenization parameters; to improve adhesion; to minimize residual stresses; to improve the uniformity, stoichiometry, and morphology of CdTe and Cu(In{sub 1{minus}x}Ga{sub x})Se{sub 2} thin films, and the efficiency of CdTe and Cu(In{sub 1{minus}x}Ga{sub x})Se{sub 2} solar cells.

  3. Understanding the electronic structure of CdSe quantum dot-fullerene (C{sub 60}) hybrid nanostructure for photovoltaic applications

    SciTech Connect (OSTI)

    Sarkar, Sunandan; Rajbanshi, Biplab; Sarkar, Pranab

    2014-09-21

    By using the density-functional tight binding method, we studied the electronic structure of CdSe quantum dot(QD)-buckminsterfullerene (C{sub 60}) hybrid systems as a function of both the size of the QD and concentration of the fullerene molecule. Our calculation reveals that the lowest unoccupied molecular orbital energy level of the hybrid CdSeQD-C{sub 60} systems lies on the fullerene moiety, whereas the highest occupied molecular orbital (HOMO) energy level lies either on the QD or the fullerene depending on size of the CdSe QD. We explored the possibility of engineering the energy level alignment by varying the size of the CdSe QD. With increase in size of the QD, the HOMO level is shifted upward and crosses the HOMO level of the C{sub 60}-thiol molecule resulting transition from the type-I to type-II band energy alignment. The density of states and charge density plot support these types of band gap engineering of the CdSe-C{sub 60} hybrid systems. This type II band alignment indicates the possibility of application of this nanohybrid for photovoltaic purpose.

  4. Linear and nonlinear transmission of Fe{sup 2+}-doped ZnSe crystals at a wavelength of 2940 nm in the temperature range 20–220 °C

    SciTech Connect (OSTI)

    Il'ichev, N N; Pashinin, P P; Gulyamova, E S; Bufetova, G A; Shapkin, P V; Nasibov, A S

    2014-03-28

    The linear and nonlinear transmission of Fe{sup 2+}:ZnSe crystals is measured at a wavelength of 2940 nm in the temperature range 20 – 220 °C. It is found that, with increasing temperature from 20 °C to 150 – 220 °C, the transmission of Fe{sup 2+}:ZnSe crystals decreases in the case of incident radiation with an intensity of ?5.5 MW cm{sup -2} and increases in the case of radiation with an intensity of 28 kW cm{sup -2}. At a temperature of 220 °C, the linear transmission almost coincides with the nonlinear transmission. The transmission spectra of Fe{sup 2+}:ZnSe crystals at temperatures of 22 and 220 °C in the wavelength range 500 – 7000 nm are presented. (active media)

  5. Nanoscale chemical phase separation in FeTe0.55Se0.45 as seen via scanning tunneling spectroscopy

    SciTech Connect (OSTI)

    He, Xiaobo [Louisiana State University; Li, Guorong [Louisiana State University; Zhang, Jiandi [Louisiana State University; Karki, A B [Louisiana State University; Jin, Rongying [Louisiana State University; Sales, Brian C [ORNL; Safa-Sefat, Athena [ORNL; McGuire, Michael A [ORNL; Mandrus, David [ORNL; Plummer, E. W. [Louisiana State University

    2011-01-01

    Atomically resolved structural and electronic properties of FeTe{sub 1-x}Se{sub x} (x = 0 and 0.45) have been studied with scanning tunneling microscopy/spectroscopy (STM/STS). In contrast to the extreme flatness of the Te-terminated FeTe surface, nanoscale chemical phase separation between Te and Se atoms is unambiguously revealed on the surface of FeTe{sub 0.55}Se{sub 0.45}. A statistical counting of the two kinds of atoms has the same ratio as that in the bulk. Remarkably, there is no electronic phase separation seen in the tunneling spectroscopy. This indicates that the optimally doped superconductor is chemically inhomogeneous but electronically homogeneous, in contrast to many correlated electron materials.

  6. The energy band structure of A{sub x}Fe{sub 2}Se{sub 2} (A = K, Rb) superconductors

    SciTech Connect (OSTI)

    Zabidi, Noriza A. [Physics Department, Centre for Defence Foundation Studies, Universiti Pertahanan Nasional Malaysia, Kuala Lumpur 59200 (Malaysia); Azhan, Muhd. Z. [Defence Science Department, Faculty of Defence Science and Technology, Universiti Pertahanan Nasional Malaysia, Kuala Lumpur 59200 (Malaysia); Rosli, A. N. [Faculty of Science and Technology, Universiti Sains Islam Malaysia, Nilai 71800, Negeri Sembilan (Malaysia); Shrivastava, Keshav N. [School of Physics, University of Hyderabad, Hyderabad 500046 (India)

    2014-03-05

    We study the band structure of antiferromagnetic A{sub x}Fe{sub 2}Se{sub 2} (A = K, Rb) superconductors by using first-principles electronic structure calculations which is density functional theory. In the vicinity of iron-vacancy, we identify the valence electrons of A{sub x}Fe{sub 2}Se{sub 2} will be filled up to the Fermi level and no semiconducting gap is observed. Hence, the A{sub x}Fe{sub 2}Se{sub 2} is a metallic instead of semiconducting which leads to superconductivity in the orbital-selective Mott phase. Similarly, there is non-vanishing density of states at the Fermi level.

  7. 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.

  8. Lead (II) selenite halides Pb{sub 3}(SeO{sub 3}){sub 2}X{sub 2} (X = Br, I): Synthesis and crystal structure

    SciTech Connect (OSTI)

    Berdonosov, P. S., E-mail: berdonosov@inorg.chem.msu.ru; Olenev, A. V.; Dolgikh, V. A. [Moscow State University (Russian Federation)

    2012-03-15

    Two lead selenite halides, Pb{sub 3}(SeO{sub 3}){sub 2}Br{sub 2} and Pb{sub 3}(SeO{sub 3}){sub 2}I{sub 2}, have been prepared by solid-phase synthesis and structurally characterized. These compounds are isotypic and can be considered 3D with a microporous framework composed of lead polyhedra (distorted Archimedean antiprisms formed by oxygen and halogen atoms). The framework contains channels oriented in the [010] direction. These channels contain selenium atoms, which are bound with framework oxygen atoms belonging to different lead polyhedra.

  9. Observation of an electron band above the Fermi level in FeTe?.??Se?.?? from in-situ surface doping

    SciTech Connect (OSTI)

    Zhang, P.; Richard, P.; Xu, N.; Xu, Y. -M.; Ma, J.; Qian, T.; Fedorov, A. V.; Denlinger, J. D.; Gu, G. D.; Ding, H.

    2014-10-27

    We used in-situ potassium (K) evaporation to dope the surface of the iron-based superconductor FeTe?.??Se?.??. The systematic study of the bands near the Fermi level confirms that electrons are doped into the system, allowing us to tune the Fermi level of this material and to access otherwise unoccupied electronic states. In particular, we observe an electron band located above the Fermi level before doping that shares similarities with a small three-dimensional pocket observed in the cousin, heavily-electron-doped KFe??xSe? compound.

  10. Solar-energy conversion by combined photovoltaic converters with CdTe and CuInSe{sub 2} base layers

    SciTech Connect (OSTI)

    Khrypunov, G. S. Sokol, E. I.; Yakimenko, Yu. I.; Meriuts, A. V.; Ivashuk, A. V.; Shelest, T. N.

    2014-12-15

    The possibility of the combined use of bifacial thin-film solar cells based on CdTe and frontal solar cells with a CuInSe{sub 2} base layer in tandem structures is experimentally confirmed. It is found that, for the use of bifacial solar cells based on cadmium telluride in a tandem structure, the optimal thickness of their base layer should be 1 ?m. The gain in the efficiency of the tandem structure, compared with an individual CuInSe{sub 2}-based solar cell, is 1.8% in the case of series-connected solar cells and 1.3%, for parallel-connected.

  11. Mesoporous TiO2 beads for high efficiency CdS/ CdSe quantum dot co-sensitized solar cells

    E-Print Network [OSTI]

    Cao, Guozhong

    Mesoporous TiO2 beads for high efficiency CdS/ CdSe quantum dot co-sensitized solar cells Ru Zhou-sensitized solar cell (QDSC) application. The photoanode films were composed of submicrometer-sized beads consisting of packed TiO2 nanocrystallites. A power conversion efficiency up to 4.05% has been achieved

  12. Campo 0. Transferencia del Conocimiento e Innovacin. Creado por la Resolucin de 23 de noviembre de 2010, donde se establece que

    E-Print Network [OSTI]

    Bilbao Arrese, Jesús Mario

    previamente desarrollados por el solicitante o de las innovaciones relevantes derivadas de su investigación participación directa en la creación de empresas basadas en la transferencia de conocimiento derivada de la publicaciones derivadas de trabajos con agentes socioeconómicos donde se describan productos comerciales

  13. Una mejora del mtodo de Steffensen en espacios En este artculo se presenta una generalizacin del mtodo de Steffensen para la

    E-Print Network [OSTI]

    Amat, Sergio

    generalización del método de Steffensen para la resolución de ecuaciones no lineales sin usar derivadas. Se numéricamente el método introducido con los métodos clásicos. Sin usar para ello ninguna derivada, el método de derivada f 0 (xk) por la siguiente expresión: f((f(xk) - xk) + xk) - f(xk) f(xk) - xk = f(f(xk)) - f(xk) f

  14. Rsum -Les films amorphes GeSe-j vapors obliquement ont une structure colonnaire trs marque. La contraction induite par photo-irradiation a t

    E-Print Network [OSTI]

    Boyer, Edmond

    -induced contraction of a-GeSe3 films has been studied with small-angle neutron scattering and scanning electron/. On illumination the films densify, and a previous small-angle neutron scattering (SANS) study /3/ showed. La contraction induite par photo-irradiation a été étudiée par diffusion des neutrons aux petits

  15. Distinct Fermi Surface Topology and Nodeless Superconducting Gap in a Tl0:58Rb0:42Fe1:72Se2 Superconductor

    E-Print Network [OSTI]

    Tian, Weidong

    -based superconductors reported so far. The Fermi surface around the M point shows a nearly isotropic superconducting gap) superconductors [6]. It is important to explore whether the high-Tc superconductiv- ity mechanism in this new FeDistinct Fermi Surface Topology and Nodeless Superconducting Gap in a ðTl0:58Rb0:42ÞFe1:72Se2

  16. Structural and dynamical properties of Bridgman-grown CdSe[subscript x]Te[subscript 1?x] (0

    E-Print Network [OSTI]

    Talwar, Devki N.

    Measurements of the Raman scattering and extended x-ray-absorption fine-structure (EXAFS) spectroscopy are reported on a series of Bridgman-grown zinc-blende CdTe[subscript 1?x]Se[subscript x] (0.35 ? x > 0.05) ternary ...

  17. Suzuki batteries The '96 to present Suzuki DR650SE comes from the factory with a Yuasa YTX9BS battery. This is a

    E-Print Network [OSTI]

    Westall, James M.

    Suzuki batteries The '96 to present Suzuki DR650SE comes from the factory with a Yuasa YTX9BS battery. This is a highquality AGM (absorbed glass mat) type battery, which is sealed and maintenance free. AGM batteries last much longer than conventional floodedcell batteries in normal service

  18. Electric Fields on Oxidized Silicon Surfaces: Static Polarization of PbSe Nanocrystals Chaya H. Ben-Porat, Oksana Cherniavskaya, and Louis Brus*

    E-Print Network [OSTI]

    . In ambient light, the nanocrystals generate static electric fields of magnitudes too weak to be caused in the oxide, and (c) the fundamental fact that the oxide is amorphous with varying local electrical propertiesElectric Fields on Oxidized Silicon Surfaces: Static Polarization of PbSe Nanocrystals Chaya H. Ben

  19. Oceanography | March 2012 213 O C E AN I C SPR E A D I N G CENT E R PRO C E S SE S |

    E-Print Network [OSTI]

    Girguis, Peter R.

    Oceanography | March 2012 213 O C E AN I C SPR E A D I N G CENT E R PRO C E S SE S | Ridge 2000 PRO, MA, USA. #12;Oceanography | Vol. 25, No.1214 communities--as well as bioelectro- chemical systems

  20. Determination of the minority carrier diffusion length in compositionally graded Cu,,In,Ga...Se2 solar cells using electron beam induced

    E-Print Network [OSTI]

    Wu, Junqiao

    , USA 2 National Renewable Energy Laboratory, Golden, Colorado 80401, USA 3 Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA 4 Division of Materials,Ga Se2 solar cells using energy dependent electron beam induced current. Gallium composition gradients

  1. Experimental investigation of exciton-LO-phonon couplings in CdSe/ZnS core/shell nanorods Holger Lange,1,* Mikhail Artemyev,2

    E-Print Network [OSTI]

    Nabben, Reinhard

    in the field of optoelectronics. CdSe nanorods have interest- ing properties, which lead to possible trioctylphosphine selenide in trioctylphos- phine oxide in the presence of hexadecylphosphonic acid as a surface- lected nanorod samples in a second step in a hexadecilamine/ trioctylphosphine oxide reaction mixture

  2. Interfacial mode coupling as the origin of the enhancement of Tc in FeSe films on SrTiO3

    SciTech Connect (OSTI)

    Lee, J. J.; Schmitt, F. T.; Moore, R. G.; Johnston, S.; Cui, Y. -T.; Li, W.; Yi, M.; Liu, Z. K.; Hashimoto, M.; Zhang, Y.; Lu, D. H.; Devereaux, T. P.; Lee, D. -H.; Shen, Z. -X.; /SIMES, Stanford /SLAC /Stanford U., Geballe Lab.

    2014-11-12

    Films of iron selenide (FeSe) one unit cell thick grown on strontium titanate (SrTiO3 or STO) substrates have recently shown superconducting energy gaps opening at temperatures close to the boiling point of liquid nitrogen (77 K), which is a record for the iron-based superconductors. The gap opening temperature usually sets the superconducting transition temperature Tc, as the gap signals the formation of Cooper pairs, the bound electron states responsible for superconductivity. To understand why Cooper pairs form at such high temperatures, we examine the role of the SrTiO3 substrate. Here we report high-resolution angle-resolved photoemission spectroscopy results that reveal an unexpected characteristic of the single-unit-cell FeSe/SrTiO3 system: shake-off bands suggesting the presence of bosonic modes, most probably oxygen optical phonons in SrTiO3, which couple to the FeSe electrons with only a small momentum transfer. Such interfacial coupling assists superconductivity in most channels, including those mediated by spin fluctuations. Our calculations suggest that this coupling is responsible for raising the superconducting gap opening temperature in single-unit-cell FeSe/SrTiO3.

  3. Microscale solar cells for high concentration on polycrystalline Cu(In,Ga)Se2 Myriam Paire,1,2,3,4,a)

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    thin film solar cell material,7 and efficiencies over 20% were achieved recently. We study CIGS to decrease with illumination. The device described in this letter is a glass/Mo/CIGS/ CdS/ZnO solar cellMicroscale solar cells for high concentration on polycrystalline Cu(In,Ga)Se2 thin films Myriam

  4. Hole drift mobility measurements in polycrystalline CuIn1-xGaxSe2 S. A. Dinca and E. A. Schiff

    E-Print Network [OSTI]

    Schiff, Eric A.

    mobility measurements on polycrystalline CuIn1-xGaxSe2 CIGS thin films incorporated into solar-cell of these properties is that solar cells fabricated from the thin- film polycrystalline materials have larger in a depletion region at the top interface with cadmium sulfide. 12 cells, originating in two laboratories, were

  5. Atomic and electronic structures of single-layer FeSe on SrTiO3(001): The role of oxygen deficiency

    SciTech Connect (OSTI)

    Bang, Junhyeok; Li, Zhi; Sun, Y. Y.; Samanta, Amit; Zhang, Y. Y.; Zhang, Wenhao; Wang, Lili; Chen, X.; Ma, Xucun; Xue, Q.-K.; Zhang, S. B.

    2013-06-06

    Using first-principles calculation, we propose an interface structure for single triple-layer FeSe on the SrTiO3(001) surface, a high-Tc superconductor found recently. The key component of this structure is the oxygen deficiency on the top layer of the SrTiO3 substrate, as a result of Se etching used in preparing the high-Tc samples. The O vacancies strongly bind the FeSe triple layer to the substrate giving rise to a (2×1) reconstruction, as observed by scanning tunneling microscopy. The enhanced binding correlates to the significant increase of Tc observed in experiment. The O vacancies also serve as the source of electron doping, which modifies the Fermi surface of the first FeSe layer by filling the hole pocket near the center of the surface Brillouin zone, as suggested from angle-resolved photoemission spectroscopy measurement.

  6. Evolution of glass properties during a substitution of S by Se in Ge28Sb12S60-xSex glass Guillaume Guery1,2

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Evolution of glass properties during a substitution of S by Se in Ge28Sb12S60-xSex glass network, Université de Bordeaux I, Avenue du Dr Schweitzer, 33608 Pessac Cedex, France. Keywords: Chalcogenide glass; Raman spectroscopy; X-ray photoelectron spectroscopy; Glass properties Author whom correspondence should

  7. A New Class of Multivariate Public Key Cryptosystems Constructed Based on Random Pseudo Cyclic Codes, K(XIII)SE(2)PKC, Realizing Coding Rate

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    A New Class of Multivariate Public Key Cryptosystems Constructed Based on Random Pseudo Cyclic present a new class of multivariate public-key cryptosystems, K(XIII)SE(2)PKC realizing the coding rate. Keyword Public key cryptosystem, Error-correcting code, Code based PKC, Cyclic code, Multivariate PKC, Gr

  8. Information Technologies Activity Report SE P T E M B E R -O C T O B E R 2 0 1 0

    E-Print Network [OSTI]

    Firestone, Jeremy

    Information Technologies Activity Report SE P T E M B E R - O C T O B E R 2 0 1 0 IT Helps UD, willing and able to seize the moment." Information Technologies (IT) was among the units Begleiter praised as the project develops. Go to the UD Mobile Web site for more information. 1 #12;Information Technologies

  9. 9 6 IEEE SOFTWARE Published by the IEEE Computer Society 0740-7459/07/$25.00 2007 IEEE of discussions with Tom Gilb, the company se-

    E-Print Network [OSTI]

    of discussions with Tom Gilb, the company se- lected Evo,1 an evolutionary project manage- ment method that Gilb first detailed in 1981.2 Evo develops the final product iteratively as new requirements are discovered system test. Evo is a rigorous process encompassing conscious risk management, similar to the later

  10. O II Seminrio Nacional de Tecnologia e Dignidade Humana visa fomentar uma reflexo interdisciplinar acerca da "dignidade da pessoa humana" no que se

    E-Print Network [OSTI]

    Paraná, Universidade Federal do

    Objetivo O II Seminário Nacional de Tecnologia e Dignidade Humana visa fomentar uma reflexão interdisciplinar acerca da "dignidade da pessoa humana" no que se refere ao uso de tecnologias de informação e de Tecnologia e Dignidade Humana Apoio 14 e 15 de maio de 2015 #12;9h00 Cerimônia de abertura do

  11. Studies on Thermoelectric Properties of n-type Polycrystalline SnSe[subscript 1-x]S[subscript x] by Iodine Doping

    E-Print Network [OSTI]

    Zhang, Qian

    Iodine-doped n-type SnSe polycrystalline by melting and hot pressing is prepared. The prepared material is anisotropic with a peak ZT of ?0.8 at about 773 K measured along the hot pressing direction. This is the first ...

  12. Characterization of Damp-Heat Degradation of CuInGaSe2 Solar Cell Components and Devices by (Electrochemical) Impedance Spectroscopy: Preprint

    SciTech Connect (OSTI)

    Pern, F. J. J.; Noufi, R.

    2011-09-01

    This work evaluated the capability of (electrochemical) impedance spectroscopy (IS, or ECIS as used here) to monitor damp heat (DH) stability of contact materials, CuInGaSe2 (CIGS) solar cell components, and devices. Cell characteristics and its variation of the CIGS devices were also examined by the ECIS.

  13. Examen de BIOESTADSTICA 3 de febrero de 2004 1) En la Sierra Morena se pueden encontrar arbustos de jara de dos tipos: jara de ldano (cistus ladanifer,

    E-Print Network [OSTI]

    Quirós, Fernando

    grandes obtuviéramos un peso medio muestral superior a 63 gramos? 3) En una práctica de ecología sobre el nivel de confianza de esta afirmación. 2) Los huevos producidos en una granja se clasifican en tres que el peso medio de los huevos de tipo "grande" que comercializa la granja es de 65 gramos, con una

  14. SE2S03, 2006 --WOLFRAM KAHL, Computing and Software, McMaster University 1.9 12 int myArray[10];

    E-Print Network [OSTI]

    Sekerinski, Emil

    Array[7] = { 0 }; /* result: [ 0, 0, 0, 0, 0, 0, 0 ] */ int myArray[7] = { }; /* Not ANSI CMaster University 1.47 51 VarArray #include /* VarArray.c */ #define SIZE 10 void printRow(int r[], intSE2S03, 2006 -- WOLFRAM KAHL, Computing and Software, McMaster University 1.9 12 Arrays int my

  15. Structural and chemical investigations of CBD-and PVD-CdS buffer layers and interfaces in Cu(In,Ga)Se2-based thin film solar cells

    E-Print Network [OSTI]

    Romeo, Alessandro

    (In,Ga)Se2-based thin film solar cells D. Abou-Rasa,b,*, G. Kostorza , A. Romeob,1 , D. Rudmannb , A Available online 8 December 2004 Abstract It is known that high-efficiency thin film solar cells based on Cu in efficiencies of solar cells with CBD- and PVD-CdS buffer layers can partly be explained by referring

  16. PHYSICAL REVIEW B 84, 064303 (2011) Hydrogen transport in superionic system Rb3H(SeO4)2: A revised cooperative migration mechanism

    E-Print Network [OSTI]

    2011-01-01

    for applications in solid-state hydrogen fuel cells, hydrogen storage, and electrochemical devices.1­4 A central problem in fuel-cell and hydrogen batteries technology is the development of cheap and efficient materials of hydrogen transport in Rb3H(SeO4)2 crystal that represents technologically promising class M3H(XO4

  17. Interface Driven Energy Filtering of Thermoelectric Power in Spark Plasma Sintered Bi2Te2.7Se0.3 Nanoplatelet Composites

    E-Print Network [OSTI]

    Xiong, Qihua

    -ray diffraction, transmission electron microscopy, thermoelectric, and thermal transport measurements illustrateInterface Driven Energy Filtering of Thermoelectric Power in Spark Plasma Sintered Bi2Te2.7Se0 that the pellet sintered at 250 °C shows a minimum grain growth and an optimal number of interfaces for efficient

  18. Palladium site ordering and the occurrence of superconductivity in Bi{sub 2}Pd{sub 3}Se{sub 2-x}S{sub x}

    SciTech Connect (OSTI)

    Weihrich, R. [Institut fuer Anorganische Chemie, Universitaet Regensburg, Universitaetsstrasse 31, D-93040 Regensburg (Germany); Matar, S.F., E-mail: matar@icmcb-bordeaux.cnrs.f [CNRS, University of Bordeaux, ICMCB, 87 avenue du Docteur A. Schweitzer, F-33600 Pessac (France); Anusca, I.; Pielnhofer, F.; Peter, P.; Bachhuber, F. [Institut fuer Anorganische Chemie, Universitaet Regensburg, Universitaetsstrasse 31, D-93040 Regensburg (Germany); Eyert, V. [Center for Electronic Correlations and Magnetism, Institute for Physics, University of Augsburg, D-86135 Augsburg (Germany)

    2011-04-15

    The crystallographic and electronic structures of compounds related to parkerite (Bi{sub 2}Ni{sub 3}S{sub 2}) are investigated with respect to the recently reported occurrence (Bi{sub 2}Pd{sub 3}Se{sub 2}) and absence (Bi{sub 2}Pd{sub 3}S{sub 2}) of superconductivity. Similarities and differences of the crystal structures are discussed within the series of solid solutions Bi{sub 2}Pd{sub 3}S{sub 2-x}Se{sub x} from powder and single crystal diffraction data. From crystal structure refinements, the question of different structures and settings of parkerite is discussed. Similar and different 2D and 3D partial Pd-Ch (Ch=S, Se) structures are related to half antiperovskite ordering schemes. To investigate the relation of low dimensional structures and the occurrence of superconductivity, electronic structures are analyzed by scalar-relativistic DFT calculations, including site projected DOS, ECOV and Fermi surfaces. -- Graphical abstract: Structure relations for perovskite type BiPd{sub 3}C, BiPd{sub 3/2}Se and BiPd{sub 3/2}S. Display Omitted Research highlights: {yields} Merging crystallographic and electronic structures studies to understand chalcogenides related to parkerite (Bi{sub 2}Ni{sub 3}S{sub 2}). {yields} Investigation in view of recently reported occurrence (Bi{sub 2}Pd{sub 3}Se{sub 2}) and absence (Bi{sub 2}Pd{sub 3}S{sub 2}) of superconductivity. {yields} Relationship of half perovskites with perovskites.

  19. Synthesis, characterization, and anomalous dielectric and conductivity performance of one-dimensional (bdaH)InSe{sub 2} (bda = 1,4-butanediamine)

    SciTech Connect (OSTI)

    Du, Ke-Zhao; Hu, Wan-Biao; Graduate School of the Chinese Academy of Sciences, Beijing 100049 ; Hu, Bing; Guan, Xiang-Feng; Huang, Xiao-Ying

    2011-11-15

    Graphical abstract: Anomalous dielectric and conductivity performance have been observed in the organic-containing indium selenide (bdaH)InSe{sub 2}, which are attributed to the water molecules existing in the crystal boundary rather than phase transition. Highlights: {yields} The title compound is the first example of organic-containing one-dimensional indium selenide. {yields} The anomalous dielectric peak is attributed to water molecules in crystal boundary. {yields} The inorganic and organic components of the title compound are connected via hydrogen bonding to form a supramolecular three-dimensional network. -- Abstract: A new indium selenide, namely (bdaH)InSe{sub 2} (1) (bda = 1,4-butanediamine) has been solvothermally synthesized and structurally characterized. It belongs to the non-centrosymmetric space group Fdd2. Its structure features an infinite one-dimensional anionic chain of [InSe{sub 2}]{sub n}{sup n-} with monoprotonated [bdaH]{sup +} as charge compensating cation. The organic [bdaH]{sup +} cations are joined into a supramolecular one-dimensional chain via N-H...N hydrogen bonding, which further interacts with the inorganic chain via N-H...Se and C-H...Se hydrogen bonding, forming a supramolecular three-dimensional network. Based on such a well-defined structure, the thermal stability, optical, conductivity, and dielectric properties were systematically investigated, showing that dielectric constant, as well as conductivity, had a hump at about 95 {sup o}C, which could be attributed to water molecules in the crystal boundary.

  20. Temperature dependence of hot-carrier relaxation in PbSe nanocrystals: An ab initio study Hua Bao,1 Bradley F. Habenicht,2 Oleg V. Prezhdo,2,*, and Xiulin Ruan1,*,

    E-Print Network [OSTI]

    Ruan, Xiulin

    in solar cells, lasers, thermoelectrics, etc.1­3 These artificial molecules can be controlled in size range in InAs,8 CdSe,9 and PbSe Refs. 10­12 nanocrystals and hence the phonon bottleneck effect- erally through the multiphonon relaxation mechanism. The fast relaxation in CdSe NCs has been

  1. Cs{sub 4}P{sub 2}Se{sub 10}: A new compound discovered with the application of solid-state and high temperature NMR

    SciTech Connect (OSTI)

    Gave, Matthew A.; Canlas, Christian G. [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Chung, In [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Department of Chemistry, Northwestern University, Evanston, IL 60208 (United States); Iyer, Ratnasabapathy G. [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Kanatzidis, Mercouri G. [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Department of Chemistry, Northwestern University, Evanston, IL 60208 (United States)], E-mail: m-kanatzidis@northwestern.edu; Weliky, David P. [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States)], E-mail: weliky@chemistry.msu.edu

    2007-10-15

    The new compound Cs{sub 4}P{sub 2}Se{sub 10} was serendipitously produced in high purity during a high-temperature synthesis done in a nuclear magnetic resonance (NMR) spectrometer. {sup 31}P magic angle spinning (MAS) NMR of the products of the synthesis revealed that the dominant phosphorus-containing product had a chemical shift of -52.8 ppm that could not be assigned to any known compound. Deep reddish brown well-formed plate-like crystals were isolated from the NMR reaction ampoule and the structure was solved with X-ray diffraction. Cs{sub 4}P{sub 2}Se{sub 10} has the triclinic space group P-1 with a=7.3587(11) A, b=7.4546(11) A, c=10.1420(15) A, {alpha}=85.938(2){sup o}, {beta}=88.055(2){sup o}, and {gamma}=85.609(2){sup o} and contains the [P{sub 2}Se{sub 10}]{sup 4-} anion. To our knowledge, this is the first compound containing this anion that is composed of two tetrahedral (PSe{sub 4}) units connected by a diselenide linkage. It was also possible to form a glass by quenching the melt in ice water, and Cs{sub 4}P{sub 2}Se{sub 10} was recovered upon annealing. The static {sup 31}P NMR spectrum at 350 deg. C contained a single peak with a -35 ppm chemical shift and a {approx}7 ppm peak width. This study highlights the potential of solid-state and high-temperature NMR for aiding discovery of new compounds and for probing the species that exist at high temperature. - Graphical abstract: The new compound Cs{sub 4}P{sub 2}Se{sub 10} was discovered following a high-temperature in situ synthesis in the NMR spectrometer and the structure was determined by single-crystal X-ray diffraction. It contains the new [P{sub 2}Se{sub 10}]{sup 4-} anion.

  2. Surface half-metallicity of CrS thin films and perfect spin filtering and spin diode effects of CrS/ZnSe heterostructure

    SciTech Connect (OSTI)

    Gao, G. Y. Yao, K. L.

    2014-11-03

    Recently, ferromagnetic zinc-blende Mn{sub 1?x}Cr{sub x}S thin films (above x?=?0.5) were fabricated experimentally on ZnSe substrate, which confirmed the previous theoretical prediction of half-metallic ferromagnetism in zinc-blende CrS. Here, we theoretically reveal that both Cr- and S-terminated (001) surfaces of the CrS thin films retain the half-metallicity. The CrS/ZnSe(001) heterogeneous junction exhibits excellent spin filtering and spin diode effects, which are explained by the calculated band structure and transmission spectra. The perfect spin transport properties indicate the potential applications of half-metallic CrS in spintronic devices. All computational results are obtained by using the density functional theory combined with nonequilibrium Green's function.

  3. Thermal studies of Se{sub 85-x}Te{sub 15}In{sub x} (x = 3,6,9,12) glasses

    SciTech Connect (OSTI)

    Sushama, D. [Dept. of Physics, MSM College, Kayamkulam, Kerala (India); George, Achamma [Dept. of Physics, St. Stephans' College, Pathanapuram, Kerala (India); Asokan, S. [Dept. of Instrumentation, Indian Institute of Science, Bangalore (India)

    2011-10-20

    Bulk glasses of compositions Se{sub 85-x}Te{sub 15}In{sub x} (x = 3,6,9,12) are prepared by melt quenching technique and Differential scanning calorimetry (DSC) is employed to study the thermal stability, crystallization mechanism as well as specific heat of these glasses. It is found that the addition of indium increases the glass transition temperature. From the heating rate dependence of the glass transition temperature the activation energy of glass transition is determined using Kissinger's equation for non-isothermal crystallization of materials. An attempt has been made to explain the variation in the value of T{sub c}, T{sub p} and {Delta}C{sub p} for the composition Se{sub 73}Te{sub 15}In{sub 12} using rigidity percolation threshold (RPT). From the values of (T{sub c}-T{sub g}) the stable glass system is determined.

  4. Spectral behavior of the optical constants in the visible/near infrared of GeSbSe chalcogenide thin films grown at glancing angle

    SciTech Connect (OSTI)

    Martin-Palma, R. J.; Ryan, Joseph V.; Pantano, C. G.

    2007-04-23

    GeSbSe chalcogenide thin films were deposited using glancing angle deposition onto transparent glass substrates for the determination of the spectral behavior of the optical constants (index of refraction n and extinction coefficient k) in the visible and near infrared ranges (400-2500 nm) as a function of the deposition angle. Computational simulations based on the matrix method were employed to determine the values of the optical constants of the different films from the experimental reflectance and transmittance spectra. A significant dependence of the overall optical behavior on the deposition angle is found. Furthermore, the band gap of the GeSbSe thin films was calculated. The accurate determination of the optical constants of films grown at glancing angle will enable the development of sculptured thin film fiber-optic chemical sensors and biosensors.

  5. The role of stoichiometric vacancy periodicity in pressure-induced amorphization of the Ga{sub 2}SeTe{sub 2} semiconductor alloy

    SciTech Connect (OSTI)

    Abdul-Jabbar, N. M. [Department of Nuclear Engineering, University of California, Berkeley, California 94720 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kalkan, B.; MacDowell, A. A. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Huang, G.-Y. [Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Gronsky, R. [Department of Materials Science and Engineering, University of California, Berkeley, California 94720 (United States); Bourret-Courchesne, E. D. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Wirth, B. D. [Department of Nuclear Engineering, University of California, Berkeley, California 94720 (United States); Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States)

    2014-08-04

    We observe that pressure-induced amorphization of Ga{sub 2}SeTe{sub 2} (a III-VI semiconductor) is directly influenced by the periodicity of its intrinsic defect structures. Specimens with periodic and semi-periodic two-dimensional vacancy structures become amorphous around 10–11?GPa in contrast to those with aperiodic structures, which amorphize around 7–8?GPa. The result is an instance of altering material phase-change properties via rearrangement of stoichiometric vacancies as opposed to adjusting their concentrations. Based on our experimental findings, we posit that periodic two-dimensional vacancy structures in Ga{sub 2}SeTe{sub 2} provide an energetically preferred crystal lattice that is less prone to collapse under applied pressure. This is corroborated through first-principles electronic structure calculations, which demonstrate that the energy stability of III-VI structures under hydrostatic pressure is highly dependent on the configuration of intrinsic vacancies.

  6. Measurement of the valence band-offset in a PbSe/ZnO heterojunction by x-ray photoelectron spectroscopy

    SciTech Connect (OSTI)

    Li Lin; Qiu Jijun; Weng Binbin; Yuan Zijian; Shi Zhisheng [School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019 (United States); Li Xiaomin; Gan Xiaoyan [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Sellers, Ian R. [Deparment of Physics, University of Oklahoma, Norman, Oklahoma 73019 (United States)

    2012-12-24

    A heterojunction of PbSe/ZnO has been grown by molecular beam epitaxy. X-ray photoelectron spectroscopy was used to directly measure the valence-band offset (VBO) of the heterojunction. The VBO, {Delta}E{sub V}, was determined as 2.51 {+-} 0.05 eV using the Pb 4p{sup 3/2} and Zn 2p{sup 3/2} core levels as a reference. The conduction-band offset, {Delta}E{sub C}, was, therefore, determined to be 0.59 {+-} 0.05 eV based on the above {Delta}E{sub V} value. This analysis indicates that the PbSe/ZnO heterojunction forms a type I (Straddling Gap) heterostructure.

  7. Defects in {sup 6}LiInSe{sub 2} neutron detector investigated by photo-induced current transient spectroscopy and photoluminescence

    SciTech Connect (OSTI)

    Cui, Yunlong; Bhattacharya, Pijush; Buliga, Vladimir; Tupitsyn, Eugene; Rowe, Emmanuel; Wiggins, Brenden; Johnstone, Daniel; Stowe, Ashley; Burger, Arnold; Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235

    2013-08-26

    {sup 6}LiInSe{sub 2} is a promising thermal neutron semiconductor detector material. The performance of the detector is affected by the carrier mobility-lifetime products. Therefore, defects that function as carrier recombination centers need to be identified. In this letter, characterization of defect levels in {sup 6}LiInSe{sub 2} by photo-induced current transient spectroscopy (PICTS) and photoluminescence is reported. PICTS measurements revealed electron-related defects located at 0.22, 0.36, and 0.55 eV and hole-related defects at 0.19, 0.30, and 0.73 eV. Free exciton and donor-acceptor pairs (DAP) emissions were observed. The PICTS defect level values are consistent with those extracted from DAP transitions.

  8. El laberinto de la indigenidad: Cómo se determina quién es indígena maya ch’orti’ en Guatemala, Honduras y El Salvador

    E-Print Network [OSTI]

    Metz, Brent

    2012-01-01

    ¿con qué criterios? ¿Qué escala es la más adecuada para definirlos, a nivel de país, de región, de municipio o de familia? La antropóloga Merlin (2009:304-6) divide la manera de distinguir a los indígenas de los no indígenas en dos categorías: a... es incorrecto políticamente pensar en indios atrasados frente a la economía política modernista; hay que pensar en indígenas cuyas culturas y derechos se deben preservar. Debido a estos cambios, la gente que negaba ser indígena ahora abraza el...

  9. DEVELOPMENT OF A NOVEL PRECURSOR FOR THE PREPARATION BY SELENIZATION OF HIGH EFFICIENCY CuInGaSe2/CdS THIN FILM SOLAR CELLS

    E-Print Network [OSTI]

    Romeo, Alessandro

    /CdS THIN FILM SOLAR CELLS N. Romeo1 , A. Bosio1 , V. Canevari2 , R. Tedeschi1 , S. Sivelli1 , A, Italy 3 Scientific and Technological Department, University of Verona, Italy 4 ETH Zürich Thin Films@phys.ethz.ch ABSTRACT: A novel precursor suitable to prepare uniform CuInGaSe2 thin films on an 1 inch2 area has been

  10. Structural and chemical investigations of CBD-and PVD-CdS buffer layers and interfaces in Cu(In,Ga)Se2-based thin film solar cells

    E-Print Network [OSTI]

    Romeo, Alessandro

    (In,Ga)Se2-based thin film solar cells D. Abou-Rasa,b,*, G. Kostorza , A. Romeob,1 , D. Rudmannb , A.N. Tiwarib,2 a ETH Zu¨rich, Institute of Applied Physics, 8093 Zu¨rich, Switzerland b ETH Zu¨rich, Thin Film Available online 8 December 2004 Abstract It is known that high-efficiency thin film solar cells based on Cu

  11. Non-Ideal p-n junction Diode of Sb{sub x}Se{sub 1-x}(x = 0.4, 0.5, 0.6, 0.7) Thin Films

    SciTech Connect (OSTI)

    Mustafa, Falah I. [Solar Energy Research Center, Renewable Energy Directorate, Ministry of Science and Technology, Baghdad (Iraq); Gupta, Shikha; Goyal, N.; Tripathi, S. K. [Department of Physics, Panjab University, Chandigarh -160014 (India)

    2011-12-12

    We have made diodes consisting of the same alloy i.e. Sb{sub x}Se{sub 1-x}(x = 0.4, 0.5, 0.6 and 0.7), but change the concentration of Sb metal from 40% to 70% atomic weight percentage. It is observed from the Hall measurements that the nature of charge carriers have changed from p- to n-type at x = 0.6 for Sb{sub x}Se{sub 1-x}. We have measured I-V characteristics of four p-n junction diodes i.e. p-Sb{sub 2}Se{sub 3}/n-Sb{sub 3}Se{sub 2}, p-Sb{sub 2}Se{sub 3}/n-Sb{sub 7}Se{sub 3}, p-SbSe/n-Sb{sub 3}Se{sub 2}, p-SbSe/n-Sb{sub 7}Se{sub 3}. From the I-V plots we have calculated the parameters as built-in voltage (V{sub bi}), forward resistance (R{sub f}), ideal factor (n), saturation current (I{sub o}), breakdown current (I{sub Bd}) and breakdown voltage (V{sub Bd}).

  12. 4, 667695, 2008 SE Atlantic

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Research Centre, Department of Geography, University College London, Pearson Building, Gower Street, London, WC1E 6BT, UK 2 NERC Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Nottingham Discussion Abstract A detailed record of benthic foraminifera carbon isotopes from the South East Atlantic

  13. Midea: Order (2013-SE-1505)

    Broader source: Energy.gov [DOE]

    DOE ordered GD Midea Air-Conditioning Equipment Co. Ltd. to pay a $416,800 civil penalty after finding Midea had manufactured and distributed in commerce in the U.S. atleast 14,968 units of basic model MWJ1-08ERN1-BI8, a noncompliant room air conditioner.

  14. ar Career Se ummarizes th

    E-Print Network [OSTI]

    Plotkin, Joshua B.

    nt prior to gra e), technology s $61,401, w nearly 68% a 9. We saw a hool, seeking graduate sc yne aduation. The y, consulting which was a s accepted posi 6% increase g graduate sc chool, 64.9% Associate to the Engineering section of the Career Services website for any student in the Class of 2010 who was browsing

  15. Hicon: Order (2013-SE-1426)

    Broader source: Energy.gov [DOE]

    DOE ordered Ningbo Hicon International Industry Company, Ltd. to pay a $1,912,714 civil penalty after finding Hicon had manufactured and distributed in commerce in the U.S. 115,126 units of basic model BD-200, a noncompliant freezer.

  16. Target: Subpoena (2010-SE-2001)

    Broader source: Energy.gov [DOE]

    DOE issued a Subpoena for Information and Production of Documents to Target Corporation requesting information regarding the compliance of various torchieres Target has distributed in commerce in the U.S.

  17. Philips: Order (2012-SE-2605)

    Broader source: Energy.gov [DOE]

    DOE ordered Philips Lighting Electronics N. A. to pay a $82,478 civil penalty after finding Philips had manufactured and distributed in commerce in the U.S. 7,498 units of basic model VEL-1S40-SC, noncompliant fluorescent lamp ballasts.

  18. News-PHaSe-EFRC

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

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  3. 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: Förster 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@QD–DNA 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 Förster 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.

  4. 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?, Aytunç; 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.

  5. 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.

  6. Indium-Gallium Segregation in CuIn$_{x}$Ga$_{1-x}$Se$_2$: An ab initio based Monte Carlo Study

    E-Print Network [OSTI]

    Ludwig, Christian D R; Felser, Claudia; Schilling, Tanja; Windeln, Johannes; Kratzer, Peter

    2010-01-01

    Thin-film solar cells with CuIn$_x$Ga$_{1-x}$Se$_2$ (CIGS) absorber are still far below their efficiency limit, although lab cells reach already 19.9%. One important aspect is the homogeneity of the alloy. Large-scale simulations combining Monte Carlo and density functional calculations show that two phases coexist in thermal equilibrium below room temperature. Only at higher temperatures, CIGS becomes more and more a homogeneous alloy. A larger degree of inhomogeneity for Ga-rich CIGS persists over a wide temperature range, which may contribute to the low observed efficiency of Ga-rich CIGS solar cells.

  7. 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.

  8. 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.

  9. 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.

  10. The picosecond dynamics of electron-hole pairs in graded and homogeneous CdS{sub x}Se{sub 1-x} semiconductors

    SciTech Connect (OSTI)

    Hane, J.K.

    1995-05-01

    Wavelength and composition dependence of the time-resolved luminescence were examined. Effects of macroscopic composition gradient and microscopic alloy disorder on e{sup {minus}}-h{sup +} pair dynamics were probed. Materials with both increasing and decreasing S content with distance from the surface were examined, where 0{le} {times} {le}1 over the full range. In these graded materials, the band gap energy also varies with position. The graded semiconductor luminescence shows strong wavelength dependence, showing diffusion in both band gap and concentration gradients. A bottleneck in the diffusion is attributed to localization occurring primarily in the materials with greatest alloy disorder, i.e. around CdS{sub 0.5}Se{sub 0.50}. Homogeneous materials were studied for x = 0, 0.25, 0.50, 0.75, 1; the time-resolved luminescence depends strongly on the composition. The mixed compositions have longer decay constants than CdS and CdSe. Observed lifetimes agree with a picture of localized states induced by the alloy disorder. For a given homogeneous crystal, no wavelength dependence of the time decays was observed. Picosecond luminescence upconversion spectroscopy was used to study further the dependence of the luminescence on composition. Large nonexponential character in the decay functions was observed in the alloys; this long time tail can be attributed to a broad distribution of relaxation times as modeled by the Kohlrausch exponential.

  11. Reaction rates of $^{64}$Ge($p,?$)$^{65}$As and $^{65}$As($p,?$)$^{66}$Se and the extent of nucleosynthesis in type I X-ray bursts

    E-Print Network [OSTI]

    Y. H. Lam; J. J. He; A. Parikh; B. A. Brown; M. Wang; B. Guo; Y. H. Zhang; X. H. Zhou; H. S. Xu

    2015-05-09

    The extent of nucleosynthesis in models of type I X-ray bursts and the associated impact on the energy released in these explosive events are sensitive to nuclear masses and reaction rates around the $^{64}$Ge waiting point. Using a recent high precision mass measurement of $^{65}$As along with large-scale shell model calculations, we have determined new thermonuclear rates of the $^{64}$Ge($p$,$\\gamma$)$^{65}$As and $^{65}$As($p$,$\\gamma$)$^{66}$Se reactions. We examine the impact of available rates for these two reactions through a representative one-zone X-ray burst model. We find that our recommended rates may strongly suppress the flow of abundances toward $A\\approx100$, in sharp contrast to recent work claiming that $^{64}$Ge is not a significant $rp$-process waiting point. Indeed, the summed mass fractions for species with $A > 70$ varies by about factors of 3 or 2 depending upon the adopted $^{64}$Ge($p$,$\\gamma$)$^{65}$As or $^{65}$As($p$,$\\gamma$)$^{66}$Se rates, respectively. Furthermore, the predictions for nuclear energy generation rate E$_\\mathrm{gen}$ at late times during the burst varies rather significantly between the models using the different rates, with differences as large as about a factor of 2.

  12. Ultra-broadband terahertz time-domain ellipsometric spectroscopy utilizing GaP and GaSe emitters and an epitaxial layer transferred photoconductive detector

    SciTech Connect (OSTI)

    Yamashita, Masatsugu, E-mail: m-yama@riken.jp; Takahashi, Hideki; Otani, Chiko [RIKEN Center for Advanced Photonics, 519-1399 Aobaaramaki, Aoba-ku, Sendai 980-0845 (Japan); Ouchi, Toshihiko [Corporate R and D Headquarters, Canon Inc., 30-2 Shimomaruko 3-Chome, Ohta-ku, Tokyo 145-8501 (Japan)

    2014-02-03

    We present a reflection-type ultra-broadband terahertz (THz) time-domain spectroscopic ellipsometry system covering the frequency range of 0.5–30 THz. GaP (110) and z-cut GaSe crystals are used as emitters to generate the THz and mid-infrared pulses, respectively, and a photoconductive antenna switch using a low-temperature grown GaAs epitaxial layer transferred on Si substrate was used as a detector. By changing the emitter between the GaP and GaSe crystals, the measurable frequency range can be easily switched from the 0.5–7.8 THz range to the 7.8–30 THz range without additional optical alignment. We demonstrated the measurement of the dielectric function in a p-type InAs wafer and the optical conductivity of an indium tin oxide (ITO) thin film. The obtained carrier density and the mobility of the ITO thin film show good agreement with that obtained by the Hall measurement.

  13. Effect of dietary fat on plasma glutathione peroxidase levels and intestinal absorption of /sup 75/Se-labeled sodium selenite in chicks

    SciTech Connect (OSTI)

    Mutanen, M.L.; Mykkaenen, H.M.

    1984-05-01

    The effect of dietary fat on the availability of selenium was investigated in chicks fed either 4 or 20% butter, olive oil, rape oil, corn oil or sunflower oil in the diet for 3 weeks after hatching. Plasma glutathione peroxidase (GSH-Px) activity was used as an indicator of the body selenium status. In addition, the intestinal absorption of sodium selenite (/sup 75/Se-labeled) was determined by using both the in vivo ligated loop procedure and oral administration of the isotope. The plasma GSH-Px levels increased with increasing proportion of the polyunsaturated fatty acids in the diet. Increasing the amount of fat from 4 to 20% significantly enhanced the GSH-Px activity in the groups receiving butter or olive oil, but had no effect in animals fed the unsaturated fats. The absorption of (/sup 75/Se)selenite from the ligated duodenal loops tended to be reduced in chicks fed corn oil or sunflower oil as compared to the animals receiving butter in their diet. On the other hand, the type of dietary fat did not appear to affect the absorption of the orally administered selenite. The present study demonstrates that the type of dietary fat can affect the plasma GSH-Px levels in chicks without altering the intestinal absorption of selenite. However, the results on the absorption of the intraduodenally injected sodium selenite suggest that dietary fat plays some role in the intestinal transport of selenium.

  14. 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.

  15. 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.

  16. Enhancement of transition temperature in Fe{sub x}Se{sub 0.5}Te{sub 0.5} film via iron vacancies

    SciTech Connect (OSTI)

    Zhuang, J. C. [Department of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189 (China); Institute for Superconducting and Electronic Materials, University of Wollongong, North Wollongong, New South Wales 2500 (Australia); Yeoh, W. K., E-mail: waikong.yeoh@sydney.edu.au, E-mail: zxshi@seu.edu.cn [Institute for Superconducting and Electronic Materials, University of Wollongong, North Wollongong, New South Wales 2500 (Australia); Australian Centre for Microscopy and Microanalysis, University of Sydney, Sydney, New South Wales 2006 (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, New South Wales 2006 (Australia); Cui, X. Y.; Ringer, S. P. [Australian Centre for Microscopy and Microanalysis, University of Sydney, Sydney, New South Wales 2006 (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, New South Wales 2006 (Australia); Kim, J. H.; Shi, D. Q.; Wang, X. L.; Dou, S. X. [Institute for Superconducting and Electronic Materials, University of Wollongong, North Wollongong, New South Wales 2500 (Australia); Shi, Z. X., E-mail: waikong.yeoh@sydney.edu.au, E-mail: zxshi@seu.edu.cn [Department of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189 (China)

    2014-06-30

    The effects of iron deficiency in Fe{sub x}Se{sub 0.5}Te{sub 0.5} thin films (0.8???x???1) on superconductivity and electronic properties have been studied. A significant enhancement of the superconducting transition temperature (T{sub C}) up to 21?K was observed in the most Fe deficient film (x?=?0.8). Based on the observed and simulated structural variation results, there is a high possibility that Fe vacancies can be formed in the Fe{sub x}Se{sub 0.5}Te{sub 0.5} films. The enhancement of T{sub C} shows a strong relationship with the lattice strain effect induced by Fe vacancies. Importantly, the presence of Fe vacancies alters the charge carrier population by introducing electron charge carriers, with the Fe deficient film showing more metallic behavior than the defect-free film. Our study provides a means to enhance the superconductivity and tune the charge carriers via Fe vacancy, with no reliance on chemical doping.

  17. Electronic structure of antifluorite Cu{sub 2}X (X = S, Se, Te) within the modified Becke-Johnson potential plus an on-site Coulomb U

    SciTech Connect (OSTI)

    Zhang, Yubo; Wang, Youwei; Xi, Lili; Qiu, Ruihao; Shi, Xun; Zhang, Peihong E-mail: pzhang3@buffalo.edu; Beijing Computational Science Research Center, Beijing 100084 ; Zhang, Wenqing E-mail: pzhang3@buffalo.edu; School of Chemistry and Chemical Engineering, and Sate Key Laboratory of Coordination Chemistry, Nanjing University, Jiangsu 210093

    2014-02-21

    The traditional photon absorbers Cu{sub 2?x}X (X = S, Se, and Te) have regained significant research attention in the search of earth-abundant photovoltaic materials. These moderate- and narrow-gap materials have also been shown to exhibit excellent thermoelectric properties recently. However, semimetallic band structures with inverted band orderings are predicted for antifluorite structure Cu{sub 2}X using density functional theory with the local density approximation or the generalized gradient approximation. We find that semiconducting band structures and normal band orderings can be obtained using the modified Becke-Johnson potential plus an on-site Coulomb U (the mBJ+U approach), which is consistent with our earlier finding for diamond-like Cu-based multinary semiconductors [Y. Zhang, J. Zhang, W. Gao, T. A. Abtew, Y. Wang, P. Zhang, and W. Zhang, J. Chem. Phys. 139, 184706 (2013)]. The trend of the chemical bonding of Cu{sub 2}X is analyzed, which shows that the positions of the valence band maximum and conduction band minimum are strongly affected by the inter-site pd and intra-site sp hybridizations, respectively. The calculated gaps of Cu{sub 2}S and Cu{sub 2}Se still seem to be underestimated compared with experimental results. We also discuss the effects of different structural phases and Cu disordering and deficiency on the bandgaps of these materials.

  18. Fabrication and testing of diamond-machined gratings in ZnSe, GaP, and bismuth germanate for the near infrared and visible

    SciTech Connect (OSTI)

    Kuzmenko, P J; Little, S L; Ikeda, Y; Kobayashi, N

    2008-06-22

    High quality immersion gratings for infrared applications have been demonstrated in silicon and germanium. To extend this technology to shorter wavelengths other materials must be investigated. We selected three materials, zinc selenide, gallium phosphide and bismuth germanate (Bi{sub 4}Ge{sub 3}O{sub 12}), based on high refractive index, good visible transmission and commercial availability in useful sizes. Crystal samples were diamond turned on an ultra-precision lathe to identify preferred cutting directions. Using this information we diamond-flycut test gratings over a range of feed rates to determine the optimal cutting conditions. For both ZnSe and GaP good surface quality was achieved at feed rates up to 1.0 cm/minute using a special compound angle diamond tool with negative rake angles on both cutting surfaces. The surface roughness of the groove facets was about 4 nm. A Zygo interferometer measured grating wavefront errors in reflection. For the ZnSe the RMS error was < {lambda}/20 at 633nm. More extensive testing was performed with a HeNe laser source and a cooled CCD camera. These measurements demonstrated high relative diffraction efficiency (> 80%), low random groove error (2.0 nm rms), and Rowland ghost intensities at < 0.1%. Preliminary tests on bismuth germanate show high tool wear.

  19. Investigation of scanning tunneling spectra on iron-based superconductor FeSe0.5Te0.5(in Chinese)

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

    Du, Z. -Y.; Fang, D. -L.; Wang, Z. -Y.; Du, G.; Yang, X.; Yang, H.; Gu, G.; -H, Wen H.

    2015-05-05

    FeSe0.5Te0.5 single crystals with superconducting critical temperature of 13.5 K are investigated by scanning tunneling microscopy/spectroscopy (STM/STS) measureflents in detail. STM image on the top surface shows an atomically resolved square lattice consisted by white and dark spots with a constant of about 3.73± 0.03 Å which is consistent with the lattice constant 3.78 Å. The Se and Te atoms with a height difference of about 0.35 Å are successfully identified since the sizes of the two kinds of atoms are different. The tunneling spectra show very large zero-bias conductance value and asymmetric coherent peaks in the superconducting state. Accordingmore »to the positions of coherence peaks, we determine the superconducting gap 2? = 5.5 meV, and the reduced gap 2?/kBTc = 4.9 is larger than the value predicted by the weak-coupling BCS theory. The zero-bias conductance at 1.7 K only have a decrease of about 40% compared with the normal state conductance, which may originate from some scattering and broadening mechanism in the material. This broadening effect will also make the superconducting gap determined by the distance between the coherence peaks larger than the exact gap value. The asymmetric structure of the tunneling spectra near the superconducting gap is induced by the hump on the background. This hump appears at temperature more than twice the superconducting critical temperature. This kind of hump has also been observed in other iron pnictides and needs further investigation. A possible bosonic mode outside the coherence peak with a mode energy ? of about 5.5 meV is observed in some tunneling spectra, and the ratio between the mode energy and superconducting transition temperature ?/kBTc ? 4.7 is roughly consistent with the universal ratio 4.3 in iron-based superconductors. The high-energy background of the spectra beyond the superconducting gaps shows a V-shape feature. The slopes of the differential conductance spectra at high energy are very different in the areas of Te-atom cluster and Se-atom cluster, and the difference extends to the energy of more than 300 meV. The differential conductance mapping has very little information about the quasi-particle interference of the superconducting state, which may result from the other strong scattering mechanism in the sample.« less

  20. CuInSe2 and its alloys are the leading choice for absorber layers in high-efficiency thin film solar cells due to their direct gap, high absorption coefficient and

    E-Print Network [OSTI]

    Rockett, Angus

    in CuInSe2. Epitaxial CuInSe2 thin films were deposited on GaAs bicrystal substrates using a hybrid film solar cells due to their direct gap, high absorption coefficient and excellent thermal stability epilayers to the GaAs bicrystal substrate. This allows isolation and optical characterization of individual

  1. Effect of carrier recombination on ultrafast carrier dynamics in thin films of the topological insulator Bi{sub 2}Se{sub 3}

    SciTech Connect (OSTI)

    Glinka, Yuri D.; Babakiray, Sercan; Johnson, Trent A.; Holcomb, Mikel B.; Lederman, David

    2014-10-27

    Transient reflectivity (TR) from thin films (6–40?nm thick) of the topological insulator Bi{sub 2}Se{sub 3} revealed ultrafast carrier dynamics, which suggest the existence of both radiative and non-radiative recombination between electrons residing in the upper cone of initially unoccupied high energy Dirac surface states (SS) and holes residing in the lower cone of occupied low energy Dirac SS. The modeling of measured TR traces allowed us to conclude that recombination is induced by the depletion of bulk electrons in films below ?20?nm thick due to the charge captured on the surface defects. We predict that such recombination processes can be observed using time-resolved photoluminescence techniques.

  2. Properties of Sb{sub 2}S{sub 3} and Sb{sub 2}Se{sub 3} thin films obtained by pulsed laser ablation

    SciTech Connect (OSTI)

    Virt, I. S.; Rudyj, I. O.; Kurilo, I. V.; Lopatynskyi, I. Ye.; Linnik, L. F.; Tetyorkin, V. V.; Potera, P.; Luka, G.

    2013-07-15

    The properties of Sb{sub 2}S{sub 3} and Sb{sub 2}Se{sub 3} thin films of variable thickness deposited onto Al{sub 2}O{sub 3}, Si, and KCl substrates are investigated by the method of pulsed laser ablation. The samples are obtained at a substrate temperature of 180 Degree-Sign C in a vacuum chamber with a residual pressure of 10{sup -5} Torr. The thickness of the films amounted to 40-1500 nm. The structure of the bulk material of the targets and films is investigated by the methods of X-ray diffraction and transmission high-energy electron diffraction, respectively. The electrical properties of the films are investigated in the temperature range of 253-310 K. It is shown that the films have semiconductor properties. The structural features of the films determine their optical parameters.

  3. Synthesis of CdS/CdSe core/shell ultra small nanostructures using new microwave assisted ultrasonic sol gel route

    SciTech Connect (OSTI)

    Goswami, Y. C., E-mail: y-goswami@yahoo.com; Kumar, Vijay, E-mail: y-goswami@yahoo.com [School of Physical Sciences, ITM University, Sithouli, Gwalior- 474001 (India); Sharma, Ranjana [Institute of Technology and Management, Sithouli, Gwalior- 474001 (India); Singh, Rajeev [Institute of Information Technology and Management, Sithouli, Gwalior, MP 474001 (India)

    2014-04-24

    Core-shell CdS/CdSe nanostructures have been synthesized by new microwave assisted ultrasonic sol gel route. The solution was obtained by dissolving cadmium acetate and Thiourea in the molar ratio 1:1 in Triethlioamine. The solution was Ultrasonically irradiated by Ultrasonic crystal at 40 Hz for 3 hours at 70°C. The sol was kept for another 24 hours for gel formation. Selenium dioxide was used as a selenium source and added separately. The gel was spin coated on Quartz and Glass slides followed by microwave heat treatment. The samples were characterized by structural morphological and optical characterization. XRD studies confirm the zinc blende phase of the CdS nanoparticles. The mean nanocrystal sizes calculated using Scherrer equation is ?1.2nm. Optical studies show the strong blue shift in the spectra due to very small size of the nanocrystals. TEM and HRTEM confirm the formation of core shell structures.

  4. Substitution of Ni for Fe in superconducting Fe?.??Te?.?Se?.? depresses the normal-state conductivity but not the magnetic spectral weight

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

    Wang, Jinghui; Tranquada, J. M.; Zhong, Ruidan; Li, Shichao; Gan, Yuan; Xu, Zhijun; Zhang, Cheng; Ozaki, T.; Matsuda, M.; Zhao, Yang; et al

    2015-01-05

    We have performed systematic resistivity and inelastic neutron scattering measurements on Fe?.???zNizTe?.?Se?.? samples to study the impact of Ni substitution on the transport properties and the low-energy (? 12 meV) magnetic excitations. It is found that, with increasing Ni doping, both the conductivity and superconductivity are gradually suppressed; in contrast, the low-energy magnetic spectral weight changes little. Comparing with the impact of Co and Cu substitution, we find that the effects on conductivity and superconductivity for the same degree of substitution grow systematically as the atomic number of the substituent deviates from that of Fe. The impact of the substituentsmore »as scattering centers appears to be greater than any contribution to carrier concentration. The fact that low-energy magnetic spectral weight is not reduced by increased electron scattering indicates that the existence of antiferromagnetic correlations does not depend on electronic states close to the Fermi energy.« less

  5. Substitution of Ni for Fe in superconducting Fe?.??Te?.?Se?.? depresses the normal-state conductivity but not the magnetic spectral weight

    SciTech Connect (OSTI)

    Wang, Jinghui [Nanjing Univ., Nanjing (China); Tranquada, J. M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zhong, Ruidan [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States); Li, Shichao [Nanjing Univ., Nanjing (China); Gan, Yuan [Nanjing Univ., Nanjing (China); Xu, Zhijun [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zhang, Cheng [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States); Ozaki, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Matsuda, M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Zhao, Yang [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Univ. of Maryland, College Park, MD (United States); Li, Qiang [Brookhaven National Lab. (BNL), Upton, NY (United States); Xu, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gu, Genda [Brookhaven National Lab. (BNL), Upton, NY (United States); Birgeneau, R. J. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wen, Jinsheng [Nanjing Univ., Nanjing (China)

    2015-01-01

    We have performed systematic resistivity and inelastic neutron scattering measurements on Fe?.???zNizTe?.?Se?.? samples to study the impact of Ni substitution on the transport properties and the low-energy (? 12 meV) magnetic excitations. It is found that, with increasing Ni doping, both the conductivity and superconductivity are gradually suppressed; in contrast, the low-energy magnetic spectral weight changes little. Comparing with the impact of Co and Cu substitution, we find that the effects on conductivity and superconductivity for the same degree of substitution grow systematically as the atomic number of the substituent deviates from that of Fe. The impact of the substituents as scattering centers appears to be greater than any contribution to carrier concentration. The fact that low-energy magnetic spectral weight is not reduced by increased electron scattering indicates that the existence of antiferromagnetic correlations does not depend on electronic states close to the Fermi energy.

  6. Substitution of Ni for Fe in superconducting Fe?.??Te?.?Se?.? depresses the normal-state conductivity but not the magnetic spectral weight

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

    Wang, Jinghui [Nanjing Univ., Nanjing (China); Tranquada, J. M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zhong, Ruidan [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States); Li, Shichao [Nanjing Univ., Nanjing (China); Gan, Yuan [Nanjing Univ., Nanjing (China); Xu, Zhijun [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zhang, Cheng [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States); Ozaki, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Matsuda, M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Zhao, Yang [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Univ. of Maryland, College Park, MD (United States); Li, Qiang [Brookhaven National Lab. (BNL), Upton, NY (United States); Xu, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gu, Genda [Brookhaven National Lab. (BNL), Upton, NY (United States); Birgeneau, R. J. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wen, Jinsheng [Nanjing Univ., Nanjing (China)

    2015-01-01

    We have performed systematic resistivity and inelastic neutron scattering measurements on Fe?.???zNizTe?.?Se?.? samples to study the impact of Ni substitution on the transport properties and the low-energy (? 12 meV) magnetic excitations. It is found that, with increasing Ni doping, both the conductivity and superconductivity are gradually suppressed; in contrast, the low-energy magnetic spectral weight changes little. Comparing with the impact of Co and Cu substitution, we find that the effects on conductivity and superconductivity for the same degree of substitution grow systematically as the atomic number of the substituent deviates from that of Fe. The impact of the substituents as scattering centers appears to be greater than any contribution to carrier concentration. The fact that low-energy magnetic spectral weight is not reduced by increased electron scattering indicates that the existence of antiferromagnetic correlations does not depend on electronic states close to the Fermi energy.

  7. Heat Capacity And Structural Relaxation In Se{sub 80-x}Te{sub 20}Ag{sub x}(x = 3 and 9) Glassy Alloys

    SciTech Connect (OSTI)

    Naqvi, S. Faheem; Saxena, N. S. [Semi-conductor and Polymer Science Laboratory, 5-6, Vigyan Bhawan, Department of Physics, University of Rajasthan, Jaipur-302004 (India)

    2011-10-20

    This paper reports the effects of annealing time and temperature on the thermodynamics of enthalpy relaxation of Se{sub 80-x}Te{sub 20}Ag{sub x} (x = 3,9) glasses. Differential Scanning Calorimetry (DSC) method is optimized for the measurement of enthalpy relaxation in the vicinity of glass transition. The recovery of excess enthalpy ({Delta}H{sub excess}) has been calculated from the knowledge of excess specific heat ({Delta}C{sub p}). It is found that excess enthalpy released ({Delta}H{sub excess}) increase with increase in annealing time (t{sub a}). From the knowledge of excess specific heat ({Delta}C{sub p}) and {Delta}H{sub excess}, it has been found that sub-T{sub g} annealing of glass leads to decrease in enthalpy of the system and thereby taking it to the more equilibrium state.

  8. 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 Förster resonance energy transfer in the system.

  9. Employing time-resolved terahertz spectroscopy to analyze carrier dynamics in thin-film Cu{sub 2}ZnSn(S,Se){sub 4} absorber layers

    SciTech Connect (OSTI)

    Guglietta, Glenn W.; Baxter, Jason B.; Choudhury, Kaushik Roy; Caspar, Jonathan V.

    2014-06-23

    We report the application of time-resolved terahertz spectroscopy (TRTS) to measure photoexcited carrier lifetimes and mobility, and to determine recombination mechanisms in Cu{sub 2}ZnSn(S,Se){sub 4} (CZTSSe) thin films fabricated from nanocrystal inks. Ultrafast time resolution permits tracking the evolution of carrier density to determine recombination rates and mechanisms. The carrier generation profile was manipulated by varying the photoexcitation wavelength and fluence to distinguish between surface, Shockley-Read-Hall (SRH), radiative, and Auger recombination mechanisms and determine rate constants. Surface and SRH recombination are the dominant mechanisms for the air/CZTSSe/SiO{sub 2}/Si film stack. Diffusion to, and then recombination at, the air-CZTSSe interface occurred on the order of 100 picoseconds, while SRH recombination lifetimes were 1–2 nanoseconds. TRTS measurements can provide information that is complementary to conventional time-resolved photoluminescence measurements and can direct the design of efficient thin film photovoltaics.

  10. Broadband Dielectric Spectroscopy of Mixed Betaine Phosphate Betaine Phosphite, CuInP_2(S_xSe_{1-x})_6 crystals and PMN-PSN-PZN Ceramics

    E-Print Network [OSTI]

    Macutkevic, Jan

    2010-01-01

    TIn the first chapter, the current ideas about crystalline disordered system are surveyed and exemplified by the results allowing for the most straightforward interpretation. Exclusive consideration is intended for broadband dielectric spectroscopy results. Several critical remarks are presented about various predefined forms of the distribution of relaxation times and it physical meaning. The second chapter is devoted to the experimental and theoretical methods of the broadband dielectric spectroscopy, which have been applied by the author to collect the original data personally. The third chapter contains results of investigations of the mixed hydrogen-bond betaine phosphite betaine phosphate phase transitions dynamics. Here distribution of the relaxation times, double well potential parameters, local polarization distributions of the investigated crystals are presented. In the fourth chapter the dielectric spectroscopy results of mixed CuInP2(SxSe1-x)6 crystals are presented, phase diagram of these crystal...

  11. Insulating and metallic spin glass in KxFe2-?-yNiySe2 (0.06 ? y ? 1.44 ) single crystals

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

    Ryu, Hyejin; Abeykoon, Milinda; Wang, Kefeng; Lei, Hechang; Lazarevic, N.; Warren, J. B.; Bozin, E. S.; Popovic, Z. V.; Petrovic, C.

    2015-05-04

    We report electron doping effects by Ni in KxFe2-?-yNiySe? (0.06 ? y ? 1.44) single crystal alloys. A rich ground state phase diagram is observed. Thus, a small amount of Ni (~ 4%) suppressed superconductivity below 1.8 K, inducing insulating spin glass magnetic ground state for higher Ni content. With further Ni substitution, metallic resistivity is restored. For high Ni concentration in the lattice the unit cell symmetry is high symmetry I4/mmm with no phase separation whereas both I4/m + I4/mmm space groups were detected in the phase separated crystals when concentration of Ni more »coincides with the absence of crystalline Fe vacancy order.« less

  12. Point defects in CdTexSe1-x crystals grown from a Te-rich solution for applications in detecting radiation

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

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

    2015-04-15

    We investigated cadmium telluride selenide (CdTeSe) crystals, newly grown by the Traveling Heater Method (THM), for the presence and abundance of point defects. Deep Level Transient spectroscopy (I-DLTS) was used to determine the energies of the traps, their capture cross sections, and densities. The bias across the detectors was varied from (1–30) V. Four types of point defects were identified, ranging from 10 meV to 0.35 eV. Two dominant traps at energies of 0.18 eV and 0.14 eV were studied in depth. Cd vacancies are found at lower concentrations than other point defects present in the material.

  13. Spatiotemporal Monte Carlo transport methods in x-ray semiconductor detectors: Application to pulse-height spectroscopy in a-Se

    SciTech Connect (OSTI)

    Fang Yuan; Badal, Andreu; Allec, Nicholas; Karim, Karim S.; Badano, Aldo

    2012-01-15

    Purpose: The authors describe a detailed Monte Carlo (MC) method for the coupled transport of ionizing particles and charge carriers in amorphous selenium (a-Se) semiconductor x-ray detectors, and model the effect of statistical variations on the detected signal. Methods: A detailed transport code was developed for modeling the signal formation process in semiconductor x-ray detectors. The charge transport routines include three-dimensional spatial and temporal models of electron-hole pair transport taking into account recombination and trapping. Many electron-hole pairs are created simultaneously in bursts from energy deposition events. Carrier transport processes include drift due to external field and Coulombic interactions, and diffusion due to Brownian motion. Results: Pulse-height spectra (PHS) have been simulated with different transport conditions for a range of monoenergetic incident x-ray energies and mammography radiation beam qualities. Two methods for calculating Swank factors from simulated PHS are shown, one using the entire PHS distribution, and the other using the photopeak. The latter ignores contributions from Compton scattering and K-fluorescence. Comparisons differ by approximately 2% between experimental measurements and simulations. Conclusions: The a-Se x-ray detector PHS responses simulated in this work include three-dimensional spatial and temporal transport of electron-hole pairs. These PHS were used to calculate the Swank factor and compare it with experimental measurements. The Swank factor was shown to be a function of x-ray energy and applied electric field. Trapping and recombination models are all shown to affect the Swank factor.

  14. Electronic structure of lanthanum copper oxychalcogenides LaCuOCh (Ch=S, Se, Te) by X-ray photoelectron and absorption spectroscopy

    SciTech Connect (OSTI)

    Rudyk, Brent W.; Blanchard, Peter E.R.; Cavell, Ronald G. [Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2 (Canada); Mar, Arthur, E-mail: arthur.mar@ualberta.ca [Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2 (Canada)

    2011-07-15

    X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge spectroscopy (XANES) have been applied to examine the electronic structures of lanthanum copper oxychalcogenides LaCuOCh (Ch=S, Se, Te), whose structure has been conventionally viewed as consisting of nominally isolated [LaO] and [CuCh] layers. However, there is evidence for weak La-Ch interactions between these layers, as seen in small changes in the satellite intensity of the La 3d XPS spectra as the chalcogen is changed and as supported by band structure calculations. The O 1s and Cu 2p XPS spectra are insensitive to chalcogen substitution. Lineshapes in the Cu 2p XPS spectra and fine-structure in the Cu L- and M-edge XANES spectra support the presence of Cu{sup +} species. The Ch XPS spectra show negative BE shifts relative to the elemental chalcogen, indicative of anionic species; these shifts correlate well with greater difference in electronegativity between the Cu and Ch atoms, provided that an intermediate electronegativity is chosen for Se. - Graphical abstract: The presence of anionic chalcogen atoms in LaCuOCh is supported by the Ch binding energies, which undergo negative shifts proportional to the polarity of the Cu-Ch bonds. Highlights: > La 3d XPS confirms La-Ch interlayer interactions between [LaO] and [CuCh] layers. > O 1s and Cu 2p XPS are insensitive to chalcogen substitution. > Cu XANES spectra support the presence of Cu{sup +} species. > Negative shifts in Ch binding energies imply anionic chalcogen atoms.

  15. VOLUME 88, NUMBER 4 P H Y S I C A L R E V I E W L E T T E R S 28 JANUARY 2002 Electronic Structure of Glassy Chalcogenides As4Se4 and As2Se3

    E-Print Network [OSTI]

    Drabold, David

    , dynamics, and electronic structure of these glasses. Krecmer et al. [2] demonstrated an opto- mechanical possible. In this Letter, we present a calculation of the electronic structure of models of g-As4Se4 usingVOLUME 88, NUMBER 4 P H Y S I C A L R E V I E W L E T T E R S 28 JANUARY 2002 Electronic Structure

  16. Surgical PediatricS ObStetricS Public health SchOOl nurSe internatiOnal health agencieS addictiOnS Shelter agencieS lOng-term care rehabilitatiOn

    E-Print Network [OSTI]

    Saskatchewan, University of

    Surgical PediatricS ObStetricS Public health SchOOl nurSe internatiOnal health agencieS addictiOrenSicS flight nurSe OccuPatiOnal health nOrthern nurSing gOvernment nurSing OfficerS Surgical PediatricS ObOnS Shelter agencieS lOng-term care rehabilitatiOn nurSe educatOr rural and remOte nurSing nOn-PrOfit SectOr f

  17. Effect of burst and recombination models for Monte Carlo transport of interacting carriers in a-Se x-ray detectors on Swank noise

    SciTech Connect (OSTI)

    Fang, Yuan; Karim, Karim S.; Badano, Aldo

    2014-01-15

    Purpose: The authors describe the modification to a previously developed Monte Carlo model of semiconductor direct x-ray detector required for studying the effect of burst and recombination algorithms on detector performance. This work provides insight into the effect of different charge generation models for a-Se detectors on Swank noise and recombination fraction. Methods: The proposed burst and recombination models are implemented in the Monte Carlo simulation package, ARTEMIS, developed byFang et al. [“Spatiotemporal Monte Carlo transport methods in x-ray semiconductor detectors: Application to pulse-height spectroscopy in a-Se,” Med. Phys. 39(1), 308–319 (2012)]. The burst model generates a cloud of electron-hole pairs based on electron velocity, energy deposition, and material parameters distributed within a spherical uniform volume (SUV) or on a spherical surface area (SSA). A simple first-hit (FH) and a more detailed but computationally expensive nearest-neighbor (NN) recombination algorithms are also described and compared. Results: Simulated recombination fractions for a single electron-hole pair show good agreement with Onsager model for a wide range of electric field, thermalization distance, and temperature. The recombination fraction and Swank noise exhibit a dependence on the burst model for generation of many electron-hole pairs from a single x ray. The Swank noise decreased for the SSA compared to the SUV model at 4 V/?m, while the recombination fraction decreased for SSA compared to the SUV model at 30 V/?m. The NN and FH recombination results were comparable. Conclusions: Results obtained with the ARTEMIS Monte Carlo transport model incorporating drift and diffusion are validated with the Onsager model for a single electron-hole pair as a function of electric field, thermalization distance, and temperature. For x-ray interactions, the authors demonstrate that the choice of burst model can affect the simulation results for the generation of many electron-hole pairs. The SSA model is more sensitive to the effect of electric field compared to the SUV model and that the NN and FH recombination algorithms did not significantly affect simulation results.

  18. Influence of Damp Heat on the Electrical, Optical, and Morphological Properties of Encapsulated CuInGaSe2 Devices: Preprint

    SciTech Connect (OSTI)

    Sundaramoorthy, R.; Pern, F. J.; Teeter, G.; Li, J. V.; Young, M.; Kuciauskas, D.; Call, N.; Yan, F.; To, B.; Johnston, S.; Noufi, R.; Gessert, T. A.

    2011-08-01

    CuInGaSe2 (CIGS) devices, encapsulated with different backsheets having different water vapor transmission rates (WVTR), were exposed to damp heat (DH) at 85C and 85% relative humidity (RH) and characterized periodically to understand junction degradation induced by moisture ingress. Performance degradation of the devices was primarily driven by an increase in series resistance within first 50 h of exposure, resulting in a decrease in fill factor and, accompanied loss in carrier concentration and widening of depletion width. Surface analysis of the devices after 700-h DH exposure showed the formation of Zn(OH)2 from hydrolysis of the Al-doped ZnO (AZO) window layer by the moisture, which was detrimental to the collection of minority carriers. Minority carrier lifetimes observed for the CIGS devices using time resolved photoluminescence (TRPL) remained relatively long after DH exposure. By etching the DH-exposed devices and re-fabricating with new component layers, the performance of reworked devices improved significantly, further indicating that DH-induced degradation of the AZO layer and/or the CdS buffer was the primary performance-degrading factor.

  19. Mechanical and thermal properties of h-MX{sub 2} (M?=?Cr, Mo, W; X?=?O, S, Se, Te) monolayers: A comparative study

    SciTech Connect (OSTI)

    Çak?r, Deniz, E-mail: deniz.cakir@uantwerpen.be; Peeters, François M., E-mail: francois.peeters@uantwerpen.be [Department of Physics, University of Antwerp, 2610 Antwerpen (Belgium); Sevik, Cem, E-mail: csevik@anadolu.edu.tr [Department of Mechanical Engineering, Faculty of Engineering, Anadolu University, Eskisehir TR 26555 (Turkey)

    2014-05-19

    Using density functional theory, we obtain the mechanical and thermal properties of MX{sub 2} monolayers (where M?=?Cr, Mo, W and X?=?O, S, Se, Te). The ?-centered phonon frequencies (i.e., A{sub 1}, A{sub 2}{sup ?}, E?, and E?), relative frequency values of A{sub 1}, and E? modes, and mechanical properties (i.e., elastic constants, Young modulus, and Poisson's ratio) display a strong dependence on the type of metal and chalcogenide atoms. In each chalcogenide (metal) group, transition-metal dichalcogenides (TMDCs) with W (O) atom are found to be much stiffer. Consistent with their stability, the thermal expansion of lattice constants for TMDCs with O (Te) is much slower (faster). Furthermore, in a heterostructure of these materials, the difference of the thermal expansion of lattice constants between the individual components becomes quite tiny over the whole temperature range. The calculated mechanical and thermal properties show that TMDCs are promising materials for heterostructures.

  20. Beta-decay properties of neutron-rich Ge, Se, Kr, Sr, Ru, and Pd isotopes from deformed quasiparticle random-phase approximation

    E-Print Network [OSTI]

    P. Sarriguren

    2015-04-07

    Beta-decay properties of even and odd-A neutron-rich Ge, Se, Kr, Sr, Ru, and Pd isotopes involved in the astrophysical rapid neutron capture process are studied within a deformed proton-neutron quasiparticle random-phase approximation. The underlying mean field is described self-consistently from deformed Skyrme Hartree-Fock calculations with pairing correlations. Residual interactions in the particle-hole and particle-particle channels are also included in the formalism. The isotopic evolution of the various nuclear equilibrium shapes and the corresponding charge radii are investigated in all the isotopic chains. The energy distributions of the Gamow-Teller strength as well as the beta-decay half-lives are discussed and compared with the available experimental information. It is shown that nuclear deformation plays a significant role in the description of the decay properties in this mass region. Reliable predictions of the strength distributions are essential to evaluate decay rates in astrophysical scenarios.

  1. Investigation of deep-level defects in Cu(In,Ga)Se{sub 2} thin films by a steady-state photocapacitance method

    SciTech Connect (OSTI)

    Hu, Xiaobo, E-mail: hxb1314@gmail.com; Sakurai, Takeaki; Akimoto, Katsuhiro [Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Yamada, Akimasa; Ishizuka, Shogo; Niki, Sigeru [National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

    2014-10-28

    The properties of defect levels located 0.8?eV above the valence band in Cu(In{sub 1?x},Ga{sub x})Se{sub 2} thin films were investigated by a steady-state photocapacitance method. When illuminated by light with a photon energy of 0.8?eV at 60?K, a fast increase, followed by a slow increase, was observed in the photocapacitance transients of all samples. Upon being re-exposed, samples with a low bandgap energy showed a slow decrease in photocapacitance transients. These observations were interpreted using a configuration coordinate model assuming two states for the 0.8?eV defect: a stable state D and its metastable state D* with a large lattice relaxation. The difference in the evolution mechanisms of the photocapacitance transients was attributed to the difference in the optical transition of carriers between the two states of the 0.8?eV defect and the valence and conduction bands.

  2. Determining conductivity and mobility values of individual components in multiphase composite Cu{sub 1.97}Ag{sub 0.03}Se

    SciTech Connect (OSTI)

    Day, Tristan W.; Brown, David R.; Snyder, G. Jeffrey, E-mail: jsnyder@caltech.edu [Department of Materials Science, California Institute of Technology, MC 309-81, Pasadena, California 91106 (United States); Zeier, Wolfgang G. [Department of Materials Science, California Institute of Technology, MC 309-81, Pasadena, California 91106 (United States); Department of Chemistry, University of Southern California, Seeley G. Mudd Bldg., 3620 McClintock Ave., Los Angeles, California 90089-1062 (United States); Melot, Brent C. [Department of Chemistry, University of Southern California, Seeley G. Mudd Bldg., 3620 McClintock Ave., Los Angeles, California 90089-1062 (United States)

    2014-10-27

    The intense interest in phase segregation in thermoelectrics as a means to reduce the lattice thermal conductivity and to modify the electronic properties from nanoscale size effects has not been met with a method for separately measuring the properties of each phase assuming a classical mixture. Here, we apply effective medium theory for measurements of the in-line and Hall resistivity of a multiphase composite, in this case Cu{sub 1.97}Ag{sub 0.03}Se. The behavior of these properties with magnetic field as analyzed by effective medium theory allows us to separate the conductivity and charge carrier mobility of each phase. This powerful technique can be used to determine the matrix properties in the presence of an unwanted impurity phase, to control each phase in an engineered composite, and to determine the maximum carrier concentration change by a given dopant, making it the first step toward a full optimization of a multiphase thermoelectric material and distinguishing nanoscale effects from those of a classical mixture.

  3. Excited state carrier dynamics in CdS{sub x}Se{sub 1-x} semisconductor alloys as studied by ultrafast fluorescence spectroscopy

    SciTech Connect (OSTI)

    Gadd, S.E.

    1995-08-01

    This dissertation discusses studies of the electron-hole pair dynamics of CdS{sub x}Se{sub 1-x} semiconductor alloys for the entire compositional range from x = 1 to x = 0 as examined by the ultrafast fluorescence techniques of time correlated single photon counting and fluorescence upconversion. Specifically, samples with x = 1, .75, .5, .25, and 0 were studied each at a spread of wavelengths about its respective emission maximum which varies according to {lambda} = 718nm - 210x nm. The decays of these samples were found to obey a Kohlrausch distribution, exp [(t/{tau}){sup {beta}}], with the exponent 3 in the range .5-.7 for the alloys. These results are in agreement with those expected for localization due to local potential variations resulting from the random distribution of sulfur and selenium atoms on the element VI A sub-lattice. This localization can be understood in terms of Anderson localization of the holes in states whose energy distribution tails into the forbidden energy band-gap. Because these states have energy dependent lifetimes, the carriers can decay via many parallel channels. This distribution of channels is the ultimate source of the Kohlrausch form of the fluorescence decays.

  4. Probing the Role of Interlayer Coupling and Coulomb Interactions on Electronic Structure in Few-Layer MoSe 2 Nanostructures

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

    Bradley, Aaron J.; M. Ugeda, Miguel; da Jornada, Felipe H.; Qiu, Diana Y.; Ruan, Wei; Zhang, Yi; Wickenburg, Sebastian; Riss, Alexander; Lu, Jiong; Mo, Sung-Kwan; et al

    2015-03-16

    Despite the weak nature of interlayer forces in transition metal dichalcogenide (TMD) materials, their properties are highly dependent on the number of layers in the few-layer two-dimensional (2D) limit. Here, we present a combined scanning tunneling microscopy/spectroscopy and GW theoretical study of the electronic structure of high quality single- and few-layer MoSe2 grown on bilayer graphene. We find that the electronic (quasiparticle) bandgap, a fundamental parameter for transport and optical phenomena, decreases by nearly one electronvolt when going from one layer to three due to interlayer coupling and screening effects. Our results paint a clear picture of the evolution ofmore »the electronic wave function hybridization in the valleys of both the valence and conduction bands as the number of layers is changed. This demonstrates the importance of layer number and electron-electron interactions on van der Waals heterostructures and helps to clarify how their electronic properties might be tuned in future 2D nanodevices.« less

  5. Thickness Effect of Al-Doped ZnO Window Layer on Damp Heat Stability of CuInGaSe2 Solar Cells: Preprint

    SciTech Connect (OSTI)

    Pern, F. J.; Mansfield, L.; DeHart, C.; Glick, S. H.; Yan, F.; Noufi, R.

    2011-07-01

    We investigated the damp heat (DH) stability of CuInGaSe2 (CIGS) solar cells as a function of thickness of the Al-doped ZnO (AZO) window layer from the 'standard' 0.12 ?m to a modest 0.50 ?m over an underlying 0.10-?m intrinsic ZnO buffer layer. The CIGS cells were prepared with external electrical contact using fine Au wire to the tiny 'standard' Ni/Al (0.05 ?m/3 ?m) metal grid contact pads. Bare cell coupons and sample sets encapsulated in a specially designed, Al-frame test structure with an opening for moisture ingress control using a TPT backsheet were exposed to DH at 85oC and 85% relative humidity, and characterized by current-voltage (I-V), quantum efficiency (QE), and (electrochemical) impedance spectroscopy (ECIS). The results show that bare cells exhibited rapid degradation within 50-100 h, accompanied by film wrinkling and delamination and corrosion of Mo and AlNi grid, regardless of AZO thickness. In contrast, the encapsulated cells did not show film wrinkling, delamination, and Mo corrosion after 168 h DH exposure; but the trend of efficiency degradation rate showed a weak correlation to the AZO thickness.

  6. '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.

  7. *Horarios destinados al transporte de personal 1. El servicio de transporte interno se realizar desde la entrada de la Universidad hasta la Meseta a partir de las 08:00 a.m. hasta las

    E-Print Network [OSTI]

    Vásquez, Carlos

    los trabajadores y en caso de quedar puestos vacios podrán ser usados por estudiantes que se Mar solo embarcarán estudiantes cuando queden puestos vacios a partir de Naiguatá. 5. Las paradas

  8. Surgical PediatricS ObStetricS Public health SchOOl nurSe internatiOnal health agencieS addictiOnS Shelter agencieS lOng-term care rehabilitatiOn

    E-Print Network [OSTI]

    Saskatchewan, University of

    OnS Shelter agencieS lOng-term care rehabilitatiOn nurSe educatOr rural and remOte nurSing nOn-PrOfit SectOr f

  9. 0.1 Imers"oes e submers"oes entre espa,cos de Banach. Destacamos esta se,c"ao da 0.0 pois em rela,c"ao `a imers"oes e submers"oes*

    E-Print Network [OSTI]

    Tausk, Daniel Victor

    0.1 Imers"oes e submers"oes entre espa,cos de Banach. Destacamos esta se,c"ao da 0.0 pois em rela,c"ao `a imers"oes e submers"oes* * o c'alculo em espa,cos de Banach cont'em algumas diferen teoria (i.e., a di* *ferencial das fun,c"oes e na se,c"ao seguinte o espa,co tangente `as variedades) 'e

  10. Probing structure-induced optical behavior in a new class of self-activated luminescent 0D/1D CaWO? metal oxide – CdSe nanocrystal composite heterostructures

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

    Han, Jinkyu [Brookhaven National Lab. (BNL), Upton, NY (United States); McBean, Coray [State Univ. of New York at Stony Brook, Stony Brook, NY (United States); Wang, Lei [State Univ. of New York at Stony Brook, Stony Brook, NY (United States); Hoy, Jessica [State Univ. of New York at Stony Brook, Stony Brook, NY (United States); Jaye, Cherno [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Liu, Haiqing [State Univ. of New York at Stony Brook, Stony Brook, NY (United States); Li, Zhuo-Qun [State Univ. of New York at Stony Brook, Stony Brook, NY (United States); Sfeir, Matthew Y. [Brookhaven National Lab. (BNL), Upton, NY (United States); Fischer, Daniel A. [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Taylor, Gordon T. [State Univ. of New York at Stony Brook, Stony Brook, NY (United States); Misewich, James A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wong, Stanislaus S. [Brookhaven National Lab. (BNL), Upton, NY (United States); State Univ. of New York at Stony Brook, Stony Brook, NY (United States)

    2015-02-10

    In this report, we synthesize and characterize the structural and optical properties of novel heterostructures composed of (i) semiconducting nanocrystalline CdSe quantum dot (QDs) coupled with (ii) both one and zero-dimensional (1D and 0D) motifs of self-activated luminescence CaWO? metal oxides. Specifically, ~4 nm CdSe QDs have been anchored onto (i) high-aspect ratio 1D nanowires, measuring ~230 nm in diameter and ~3 ?m in length, as well as onto (ii) crystalline 0D nanoparticles (possessing an average diameter of ~ 80 nm) of CaWO? through the mediation of 3-mercaptopropionic acid (MPA) as a connecting linker. Composite formation was confirmed by complementary electron microscopy and spectroscopy (i.e. IR and Raman) data. In terms of luminescent properties, our results show that our 1D and 0D heterostructures evince photoluminescence (PL) quenching and shortened PL lifetimes of CaWO? as compared with unbound CaWO?. We propose that a photo-induced electron transfer process occurs from CaWO? to CdSe QDs, a scenario which has been confirmed by NEXAFS measurements and which highlights a decrease in the number of unoccupied orbitals in the conduction bands of CdSe QDs. By contrast, the PL signature and lifetimes of MPA-capped CdSe QDs within these heterostructures do not exhibit noticeable changes as compared with unbound MPA-capped CdSe QDs. The striking difference in optical behavior between CaWO? nanostructures and CdSe QDs within our heterostructures can be correlated with the relative positions of their conduction and valence energy band levels. In addition, the PL quenching behaviors for CaWO? within the heterostructure configuration were examined by systematically varying (i) the quantities and coverage densities of CdSe QDs as well as (ii) the intrinsic morphology (and by extension, the inherent crystallite size) of CaWO? itself.

  11. Cu(In,Ga)Se2 alloys are the leading choice for absorber layers in high-efficiency thin film solar cells due to their direct gap, high absorption

    E-Print Network [OSTI]

    Rockett, Angus

    film solar cells due to their direct gap, high absorption coefficient and excellent thermal stability]/[In+Ga]SubstrateCrystalSample *Negligible amount of Ga diffused into back of film from substrate; not detectable by EDX Device structure GaAs(In,Ga)SePhotoluminescence Excitation Spectroscopy of Cu(In,Ga)Se22 Thin FilmsThin Films Damon Hebert, Julio Soares, Marie Mayer, Angus

  12. Probing structure-induced optical behavior in a new class of self-activated luminescent 0D/1D CaWO? metal oxide – CdSe nanocrystal composite heterostructures

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

    Han, Jinkyu; McBean, Coray; Wang, Lei; Hoy, Jessica; Jaye, Cherno; Liu, Haiqing; Li, Zhuo-Qun; Sfeir, Matthew Y.; Fischer, Daniel A.; Taylor, Gordon T.; et al

    2015-01-30

    In this report, we synthesize and characterize the structural and optical properties of novel heterostructures composed of (i) semiconducting nanocrystalline CdSe quantum dot (QDs) coupled with (ii) both one and zero-dimensional (1D and 0D) motifs of self-activated luminescence CaWO? metal oxides. Specifically, ~4 nm CdSe QDs have been anchored onto (i) high-aspect ratio 1D nanowires, measuring ~230 nm in diameter and ~3 ?m in length, as well as onto (ii) crystalline 0D nanoparticles (possessing an average diameter of ~ 80 nm) of CaWO? through the mediation of 3-mercaptopropionic acid (MPA) as a connecting linker. Composite formation was confirmed by complementarymore »electron microscopy and spectroscopy (i.e. IR and Raman) data. In terms of luminescent properties, our results show that our 1D and 0D heterostructures evince photoluminescence (PL) quenching and shortened PL lifetimes of CaWO? as compared with unbound CaWO?. We propose that a photo-induced electron transfer process occurs from CaWO? to CdSe QDs, a scenario which has been confirmed by NEXAFS measurements and which highlights a decrease in the number of unoccupied orbitals in the conduction bands of CdSe QDs. By contrast, the PL signature and lifetimes of MPA-capped CdSe QDs within these heterostructures do not exhibit noticeable changes as compared with unbound MPA-capped CdSe QDs. The striking difference in optical behavior between CaWO? nanostructures and CdSe QDs within our heterostructures can be correlated with the relative positions of their conduction and valence energy band levels. In addition, the PL quenching behaviors for CaWO? within the heterostructure configuration were examined by systematically varying (i) the quantities and coverage densities of CdSe QDs as well as (ii) the intrinsic morphology (and by extension, the inherent crystallite size) of CaWO? itself.« less

  13. Comparison of Sn-doped and nonstoichiometric vertical-Bridgman-grown crystals of the topological insulator Bi{sub 2}Te{sub 2}Se

    SciTech Connect (OSTI)

    Kushwaha, S. K. Gibson, Q. D.; Cava, R. J.; Xiong, J.; Ong, N. P.; Pletikosic, I.; Weber, A. P.; Fedorov, A. V.; Valla, T.

    2014-04-14

    A comparative study of the properties of topological insulator Bi{sub 2}Te{sub 2}Se (BTS) crystals grown by the vertical Bridgeman method is described. Two defect mechanisms that create acceptor impurities to compensate for the native n-type carriers are compared: Bi excess, and light Sn doping. Both methods yield low carrier concentrations and an n-p crossover over the length of the grown crystal boules, but lower carrier concentrations and higher resistivities are obtained for the Sn-doped crystals, which reach carrier concentrations as low as 8?×?10{sup 14}?cm{sup ?3}. Further, the temperature dependent resistivities for the Sn-doped crystals display strongly activated behavior at high temperatures, with a characteristic energy of half the bulk band gap. The (001) cleaved Sn-doped BTS crystals display high quality Shubnikov de Haas (SdH) quantum oscillations due to the topological surface state electrons. Angle resolved photoelectron spectroscopy (ARPES) characterization shows that the Fermi energy (E{sub F}) for the Sn-doped crystals falls cleanly in the surface states with no interference from the bulk bands, which the Dirac point for the surface states lies approximately 60?meV below the top of the bulk valence band maximum, and allows for a determination of the bulk and surface state carrier concentrations as a function of Energy near E{sub F}. Electronic structure calculations that compare Bi excess and Sn dopants in BTS demonstrate that Sn acts as a special impurity, with a localized impurity band that acts as a charge buffer occurring inside the bulk band gap. We propose that the special resonant level character of Sn in BTS gives rise to the exceptionally low carrier concentrations and activated resistivities observed.

  14. Seed-mediated synthesis, properties and application of {gamma}-Fe{sub 2}O{sub 3}-CdSe magnetic quantum dots

    SciTech Connect (OSTI)

    Lin, Alex W.H.; Ang, Chung Yen; Patra, Pranab K.; Han Yu; Gu Hongwei; Le Breton, Jean-Marie; Juraszek, Jean; Chiron, Hubert; Papaefthymiou, Georgia C.; Tamil Selvan, Subramanian; Ying, Jackie Y.

    2011-08-15

    Seed-mediated growth of fluorescent CdSe quantum dots (QDs) around {gamma}-Fe{sub 2}O{sub 3} magnetic cores was performed at high temperature (300 deg. C) in the presence of organic surfactants. Bi-functional magnetic quantum dots (MQDs) with tunable emission properties were successfully prepared. The as-synthesized MQDs were characterized by high-resolution transmission electron microscopy (HRTEM) and dynamic light scattering (DLS), which confirmed the assembly of heterodimers. When a longer growth period was employed, a homogeneous dispersion of QDs around a magnetic nanoparticle was obtained. The magnetic properties of these nanocomposites were examined. The MQDs were superparamagnetic with a saturation magnetization of 0.40 emu/g and a coercivity of 138 Oe at 5 K. To demonstrate their potential application in bio-labeling, these MQDs were coated with a thin silica shell, and functionalized with a polyethylene glycol (PEG) derivative. The functionalized MQDs were effectively used for the labeling of live cell membranes of 4T1 mouse breast cancer cells and HepG2 human liver cancer cells. - Graphical abstract: (a) HRTEM image of oleic acid capped MPs. The size of MPs ranges from 8 to 10 nm. (b) XRD pattern of {gamma}-Fe{sub 2}O{sub 3} MPs. Highlights: > The fabrication of MQDs through a seed-mediated approach has been demonstrated. > The formation and assembly of these bi-functional nanocomposites have been elucidated. > The MQDs exhibit superparamagnetism and tunable emissions characteristic of the components. > MQDs with thin silica coating were successfully employed in the labeling of cancer cell membranes.

  15. Reliable wet-chemical cleaning of natively oxidized high-efficiency Cu(In,Ga)Se{sub 2} thin-film solar cell absorbers

    SciTech Connect (OSTI)

    Lehmann, Jascha; Lehmann, Sebastian; Lauermann, Iver; Rissom, Thorsten; Kaufmann, Christian A.; Lux-Steiner, Martha Ch.; Bär, Marcus; Sadewasser, Sascha

    2014-12-21

    Currently, Cu-containing chalcopyrite-based solar cells provide the highest conversion efficiencies among all thin-film photovoltaic (PV) technologies. They have reached efficiency values above 20%, the same performance level as multi-crystalline silicon-wafer technology that dominates the commercial PV market. Chalcopyrite thin-film heterostructures consist of a layer stack with a variety of interfaces between different materials. It is the chalcopyrite/buffer region (forming the p-n junction), which is of crucial importance and therefore frequently investigated using surface and interface science tools, such as photoelectron spectroscopy and scanning probe microscopy. To ensure comparability and validity of the results, a general preparation guide for “realistic” surfaces of polycrystalline chalcopyrite thin films is highly desirable. We present results on wet-chemical cleaning procedures of polycrystalline Cu(In{sub 1-x}Ga{sub x})Se{sub 2} thin films with an average x?=?[Ga]/([In]?+?[Ga])?=?0.29, which were exposed to ambient conditions for different times. The hence natively oxidized sample surfaces were etched in KCN- or NH{sub 3}-based aqueous solutions. By x-ray photoelectron spectroscopy, we find that the KCN treatment results in a chemical surface structure which is – apart from a slight change in surface composition – identical to a pristine as-received sample surface. Additionally, we discover a different oxidation behavior of In and Ga, in agreement with thermodynamic reference data, and we find indications for the segregation and removal of copper selenide surface phases from the polycrystalline material.

  16. Rare-earth transition-metal gallium chalcogenides RE{sub 3}MGaCh{sub 7} (M=Fe, Co, Ni; Ch=S, Se)

    SciTech Connect (OSTI)

    Rudyk, Brent W.; Stoyko, Stanislav S.; Oliynyk, Anton O.; Mar, Arthur, E-mail: arthur.mar@ualberta.ca

    2014-02-15

    Six series of quaternary rare-earth transition-metal chalcogenides RE{sub 3}MGaCh{sub 7} (M=Fe, Co, Ni; Ch=S, Se), comprising 33 compounds in total, have been prepared by reactions of the elements at 1050 °C (for the sulphides) or 900 °C (for the selenides). They adopt noncentrosymmetric hexagonal structures (ordered Ce{sub 3}Al{sub 1.67}S{sub 7}-type, space group P6{sub 3}, Z=2) with cell parameters in the ranges of a=9.5–10.2 Å and c=6.0–6.1 Å for the sulphides and a=10.0–10.5 Å and c=6.3–6.4 Å for the selenides as refined from powder X-ray diffraction data. Single-crystal structures were determined for five members of the sulphide series RE{sub 3}FeGaS{sub 7} (RE=La, Pr, Tb) and RE{sub 3}CoGaS{sub 7} (RE=La, Tb). The highly anisotropic crystal structures consist of one-dimensional chains of M-centred face-sharing octahedra and stacks of Ga-centred tetrahedra all pointing in the same direction. Magnetic measurements on the sulphides reveal paramagnetic behaviour in some cases and long-range antiferromagnetic behaviour with low Néel temperatures (15 K or lower) in others. Ga L-edge XANES spectra support the presence of highly cationic Ga tetrahedral centres with a tendency towards more covalent Ga–Ch character on proceeding from the sulphides to the selenides. Band structure calculations on La{sub 3}FeGaS{sub 7} indicate that the electronic structure is dominated by Fe 3d-based states near the Fermi level. - Graphical abstract: The series of chalcogenides RE{sub 3}MGaS{sub 7}, which form for a wide range of rare-earth and transition metals (M=Fe, Co, Ni), adopt highly anisotropic structures containing chains of M-centred octahedra and stacks of Ga-centred tetrahedra. Display Omitted - Highlights: • Six series (comprising 33 compounds) of chalcogenides RE{sub 3}MGaCh{sub 7} were prepared. • They adopt noncentrosymmetric hexagonal structures with high anisotropy. • Most compounds are paramagnetic; some show antiferromagnetic ordering. • Ga L-edge XANES confirms presence of cationic Ga species.

  17. Effect of annealing on the kinetic properties and band parameters of Hg{sub 1?x?y}Cd{sub x}Eu{sub y}Se semiconductor crystals

    SciTech Connect (OSTI)

    Kovalyuk, T. T. Maistruk, E. V.; Maryanchuk, P. D.

    2014-12-15

    The results of studies of the kinetic properties of Hg{sub 1?x?y}Cd{sub x}Eu{sub y}Se semiconductor crystals in the ranges of temperatures T = 77–300 K and magnetic fields H = 0.5–5 kOe before and after heat treatment of the samples in Se vapors are reported. It is established that annealing of the samples in Se vapors induces a decrease in the electron concentration. From the concentration dependence of the electron effective mass at the Fermi level, the band gap, the matrix element of interband interaction, and the electron effective mass at the bottom of the conduction band are determined.

  18. Observation of an electron band above the Fermi level in FeTe{sub 0.55}Se{sub 0.45} from in-situ surface doping

    SciTech Connect (OSTI)

    Zhang, P.; Ma, J.; Qian, T.; Richard, P. Ding, H.; Xu, N.; Xu, Y.-M.; Fedorov, A. V.; Denlinger, J. D.; Gu, G. D.

    2014-10-27

    We used in-situ potassium (K) evaporation to dope the surface of the iron-based superconductor FeTe{sub 0.55}Se{sub 0.45}. The systematic study of the bands near the Fermi level confirms that electrons are doped into the system, allowing us to tune the Fermi level of this material and to access otherwise unoccupied electronic states. In particular, we observe an electron band located above the Fermi level before doping that shares similarities with a small three-dimensional pocket observed in the cousin, heavily electron-doped KFe{sub 2?x}Se{sub 2} compound.

  19. 174. THE EFFECTS OF RESIDENCE TIME ON THE RETENTION OF ARSENATE BY GOETHITE. S.E. O'Reilly and D.L. Sparks, Department of Plant and Soil Sciences, University

    E-Print Network [OSTI]

    Sparks, Donald L.

    174. THE EFFECTS OF RESIDENCE TIME ON THE RETENTION OF ARSENATE BY GOETHITE. S.E. O'Reilly and D on goethite. Batch sorption and desorption studies were conducted at pH 6 for periods up to 2 months. Arsenate sorption increased slowly with time. As residence time between arsenate and goethite increased

  20. Aero III/IV Conformal Mapping Handout 1 A. G. Walton Under the transformation ' sE5 ' E%c+ n E%c+c a set of points in the 5E%c+ plane

    E-Print Network [OSTI]

    Walton, Andrew G

    Aero III/IV Conformal Mapping Handout 1 A. G. Walton Maps Under the transformation ' sE5 ' E%c+ n with centre off the real axis transforms to an aerofoil with camber (iii). #12;Aero III/IV Conformal Mapping

  1. Anomalous transport in an n-type topological insulator ultrathin Bi2Se3 film Toru Hirahara,1,* Yusuke Sakamoto,1 Yasuo Takeichi,2 Hidetoshi Miyazaki,3 Shin-ichi Kimura,3 Iwao Matsuda,2

    E-Print Network [OSTI]

    Hasegawa, Shuji

    Anomalous transport in an n-type topological insulator ultrathin Bi2Se3 film Toru Hirahara,1, the insulating bulk carriers will freeze out and only the metallic surface states should contribute-purity insulating samples.10­15 This is partly due to the different environment in which ARPES and transport mea

  2. 6 de septiembre de 2007 Probabilidad I U.A.M. curso 2006/07 1. En la campa~na de oto~no de vacunacion anti-gripal se administro la vacuna al 15 % de la poblacion.

    E-Print Network [OSTI]

    Fernández Gallardo, Pablo

    ´on anti-gripal se administr´o la vacuna al 15 % de la poblaci´on. Estudios realizados a lo largo del densidad conjunta f(x, y) = k(x - y) 0 densidad marginales. b) Para cada x (0, 1), la funci´on de densidad condicionada de Y dado X = x y la E(Y/X = 1 2

  3. Rgulirement, Gosciences-Infos se fait l'cho du rayonnement international de GM, mme si son format est trop rduit pour rendre compte de l'tendue relle de ces activits. Le

    E-Print Network [OSTI]

    Demouchy, Sylvie

    - édito Régulièrement, Géosciences-Infos se fait l'écho du rayonnement international de GM, même si-chercheurs du laboratoire dans pas moins de cinq sessions du congrès de l'AGU à San Francisco. L'attrait de GM CNRS-Organismes (Algérie, Australie, Egypte, Irlande, Maroc, Taïwan...). GM est particulièrement

  4. Influence of different sulfur to selenium ratios on the structural and electronic properties of Cu(In,Ga)(S,Se){sub 2} thin films and solar cells formed by the stacked elemental layer process

    SciTech Connect (OSTI)

    Mueller, B. J.; Zimmermann, C.; Haug, V. Koehler, T.; Zweigart, S.; Hergert, F.; Herr, U.

    2014-11-07

    In this study, we investigate the effect of different elemental selenium to elemental sulfur ratios on the chalcopyrite phase formation in Cu(In,Ga)(S,Se){sub 2} thin films. The films are formed by the stacked elemental layer process. The structural and electronic properties of the thin films and solar cells are analyzed by means of scanning electron microscopy, glow discharge optical emission spectrometry, X-ray diffraction, X-ray fluorescence, Raman spectroscopy, spectral photoluminescence as well as current-voltage, and quantum efficiency measurements. The influence of different S/(S+Se) ratios on the anion incorporation and on the Ga/In distribution is investigated. We find a homogenous sulfur concentration profile inside the film from the top surface to the bottom. External quantum efficiency measurements show that the band edge of the solar cell device is shifted to shorter wavelength, which enhances the open-circuit voltages. The relative increase of the open-circuit voltage with S/(S+Se) ratio is lower than expected from the band gap energy trend, which is attributed to the presence of S-induced defects. We also observe a linear decrease of the short-circuit current density with increasing S/(S+Se) ratio which can be explained by a reduced absorption. Above a critical S/(S+Se) ratio of around 0.61, the fill factor drops drastically, which is accompanied by a strong series resistance increase which may be attributed to changes in the back contact or p-n junction properties.

  5. The solubility of selenate-AFt (3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}3CaSeO{sub 4}{center_dot}37.5H{sub 2}O) and selenate-AFm (3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}CaSeO{sub 4}{center_dot}xH{sub 2}O)

    SciTech Connect (OSTI)

    Baur, Isabel; Johnson, C. Annette

    2003-11-01

    The Se(VI)-analogues of ettringite and monosulfate, selenate-AFt (3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}3CaSeO{sub 4}{center_dot}37.5H{sub 2}O), and selenate-AFm (3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}CaSeO{sub 4}{center_dot}xH{sub 2}O) were synthesised and characterised by bulk chemical analysis and X-ray diffraction. Their solubility products were determined from a series of batch and resuspension experiments conducted at 25 deg. C. For selenate-AFt suspensions, the pH varied between 11.37 and 11.61, and a solubility product, log K{sub so}=61.29{+-}0.60 (I=0 M), was determined for the reaction 3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}3CaSeO{sub 4}{center_dot}37.5H{sub 2}O+12 H{sup +} implies 6Ca{sup 2+}+2Al{sup 3+}+3SeO{sub 4}{sup 2-}+43.5H{sub 2}O. Selenate-AFm synthesis resulted in the uptake of Na, which was leached during equilibration and resuspension. For the pH range of 11.75 to 11.90, a solubility product, log K{sub so}=73.40{+-}0.22 (I=0 M), was determined for the reaction 3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}CaSeO{sub 4}{center_dot}xH{sub 2}O+12 H{sup +} implies 4Ca{sup 2+}+2Al{sup 3+}+SeO{sub 4}{sup 2-}+(x+6)H{sub 2}O. Thermodynamic modelling suggested that both selenate-AFt and selenate-AFm are stable in the cementitious matrix; and that in a cement limited in sulfate, selenate concentration may be limited by selenate-AFm to below the millimolar range above pH 12.

  6. The Quadrangle Club The Quadrangle Club 1155 E. 57th Street Chicago, IL 60637 773.702.7221

    E-Print Network [OSTI]

    with Cilantro-Lime Mayo Vegetable Wonton, Hoisin Sauce, Green Onion Crisp Ravioli with Tomato Caponata Menu Hors

  7. Behavioral/Systems/Cognitive Estradiol Selectively Enhances Auditory Function in Avian

    E-Print Network [OSTI]

    Rubel, Edwin

    for the majority of studies on this topic, express hor- mone receptors (Bernard et al., 1999; Gahr, 2001; Jeong et

  8. 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.

  9. 1) Dos grafos G=(V,E) y H=(A,B) son isomorfos si existe una funcin biyectiva entre los conjuntos de vrtices de G y H que preserva las relaciones de adyacencia. Todava no se conoce un algoritmo

    E-Print Network [OSTI]

    Meza, Oscar J.

    conjuntos de vértices de G y H que preserva las relaciones de adyacencia. Todavía no se conoce un algoritmo múltiples ni bucles. Un algoritmo "ingenuo" para determinar si G y H son isomorfos probaría con las n! biyecciones. Un algoritmo de backtracking podría funcionar mejor si tratamos de disminuir el tamaño del grafo

  10. Secondary Particle Data Observations Marcus Palm

    E-Print Network [OSTI]

    McDonald, Kirk

    runs in "scan valley": · Hor pos: [-18, -11] · Vert pos: [-8, 0] ­ No probe ­ 14 GeV/c · Target out runs in "scan valley": · Hor pos: [-18, -11] · Vert pos: [-8, 0] ­ No probe · No major changes from low intensity ­ All runs in "scan valley": · Hor pos: [-18, -11] · Vert pos: [-8, 0] ­ No probe · Decreasing

  11. Structural and conductivity studies of CsK(SO{sub 4}){sub 0.32}(SeO{sub 4}){sub 0.68}Te(OH){sub 6}

    SciTech Connect (OSTI)

    Djemel, M.; Abdelhedi, M.; Dammak, M.; Kolsi, A.W.

    2012-12-15

    The compound CsK(SO{sub 4}){sub 0.32}(SeO{sub 4}){sub 0.68}Te(OH){sub 6} crystallizes in the monoclinic P2{sub 1}/n space group. It was analyzed, at room temperature, using X-ray diffractometer data. The main feature of these atomic arrangements is the coexistence of three and different anions (SO{sub 4}{sup 2-}, SeO{sub 4}{sup 2-} and TeO{sub 6}{sup 6-}groups) in the unit cell, connected by hydrogen bonds which make the building of the crystal. The thermal analysis of the title compound shows three distinct endothermal peaks at 435, 460 and 475 K. Complex impedance measurements are performed on this material as a function of both temperature and frequency. The electric conduction has been studied. The temperature dependence on the conductivity indicates that the sample became an ionic conductor at high temperature. - Graphical abstract: Projection of crystal structure CsK(SO{sub 4}){sub 0.32}(SeO{sub 4}){sub 0.68}Te(OH){sub 6} on the ab plane. Highlights: Black-Right-Pointing-Pointer We have studied the results of the crystal structure of the new mixed compound. Black-Right-Pointing-Pointer We have characterized the phase transition observed in DSC curve. Black-Right-Pointing-Pointer The protonic conduction in our material is probably due to a hopping mechanism.

  12. Solar Cells from Plastics? Mission Possible at the PHaSE Energy Research Center, UMass Amherst (A "Life at the Frontiers of Energy Research" contest entry from the 2011 Energy Frontier Research Centers (EFRCs) Summit and Forum)

    ScienceCinema (OSTI)

    Russell, Thomas P; Lahti, Paul M. (PHaSE - Polymer-Based Materials for Harvesting Solar Energy); PHaSE Staff

    2011-11-03

    'Solar Cells from Plastics? Mission Possible at the PHaSE Energy Research Center, UMass Amherst' was submitted by the Polymer-Based Materials for Harvesting Solar Energy (PHaSE) EFRC to the 'Life at the Frontiers of Energy Research' video contest at the 2011 Science for Our Nation's Energy Future: Energy Frontier Research Centers (EFRCs) Summit and Forum. Twenty-six EFRCs created short videos to highlight their mission and their work. PHaSE, an EFRC co-directed by Thomas P. Russell and Paul M. Lahti at the University of Massachusetts, Amherst, is a partnership of scientists from six institutions: UMass (lead), Oak Ridge National Laboratory, Pennyslvania State University, Rensselaer Polytechnic Institute, and the University of Pittsburgh. The Office of Basic Energy Sciences in the U.S. Department of Energy's Office of Science established the 46 Energy Frontier Research Centers (EFRCs) in 2009. These collaboratively-organized centers conduct fundamental research focused on 'grand challenges' and use-inspired 'basic research needs' recently identified in major strategic planning efforts by the scientific community. The overall purpose is to accelerate scientific progress toward meeting the nation's critical energy challenges.

  13. Liquid precursor inks for deposition of In--Se, Ga--Se and In--Ga--Se

    DOE Patents [OSTI]

    Curtis, Calvin J.; Hersh, Peter A.; Miedaner, Alexander; Habas, Susan; van Hest, Maikel; Ginley, David S.

    2015-08-11

    An ink includes a solution of selenium in ethylene diamine solvent and a solution of at least one metal salt selected from the group consisting of an indium salt or a gallium salt in at least one solvent including an organic amide. The organic amide can include dimethylformamide. The organic amide can include N-methylpyrrolidone.

  14. CNA: Compromise Agreement (2013-SE-1430)

    Broader source: Energy.gov [DOE]

    DOE and CNA International, Inc., d/b/a MC Appliance Corp. entered into a Compromise Agreement to resolve a case involving the distribution in commerce of noncompliant freezers.

  15. GE Lighting Solutions: Order (2013-SE-4901)

    Broader source: Energy.gov [DOE]

    DOE ordered General Electric Lighting Solutions, LLC to pay a $5,360 civil penalty after finding GE Lighting Solutions had manufactured and distributed in commerce in the U.S. 30 units of basic model DR4-RTFB-23B and 177 units (of which 85 units remain in inventory) of basic model DR4-RTFB-77A-002, noncompliant traffic signal modules.

  16. Lutron Electronics: Proposed Penalty (2012-SE-3796)

    Broader source: Energy.gov [DOE]

    DOE alleged in a Notice of Proposed Civil Penalty that Lutron Electronics Co., Inc. manufactured and distributed noncompliant class A external power supplies in the U.S.

  17. Lutron Electronics: Noncompliance Determination (2012-SE-3796)

    Broader source: Energy.gov [DOE]

    DOE issued a Notice of Noncompliance Determination to Lutron Electronics Co., Inc. finding that a variety of Class A external power supply basic models do not comport with the energy conservation standards.

  18. Lutron Electronics: Order (2012-SE-3796)

    Broader source: Energy.gov [DOE]

    DOE ordered Lutron Electronics Co., Inc. to pay a $13,000 civil penalty after finding Lutron Electronics had manufactured and distributed in commerce in the U.S. at least 79,000 units of various basic models, noncompliant Class A external power supplies.

  19. Aktiebolaget SKF SE-415 50 Gteborg, Sweden

    E-Print Network [OSTI]

    Cambridge, University of

    , mechatronics, services and lubrication systems. The Group's service offer includes technical support, maintenance services, engineering consultancy and training. SKF is represented in more than 130 countries

  20. Midea: Penalty Notice Withdrawal (2010-SE-0110)

    Broader source: Energy.gov [DOE]

    DOE withdrew its January 26, 2012 Notice of Proposed Civil Penalty, but retained the right to take further enforcement actions.