Sample records for band-gap semiconductor metal

  1. Narrow band gap amorphous silicon semiconductors

    DOE Patents [OSTI]

    Madan, A.; Mahan, A.H.

    1985-01-10T23:59:59.000Z

    Disclosed is a narrow band gap amorphous silicon semiconductor comprising an alloy of amorphous silicon and a band gap narrowing element selected from the group consisting of Sn, Ge, and Pb, with an electron donor dopant selected from the group consisting of P, As, Sb, Bi and N. The process for producing the narrow band gap amorphous silicon semiconductor comprises the steps of forming an alloy comprising amorphous silicon and at least one of the aforesaid band gap narrowing elements in amount sufficient to narrow the band gap of the silicon semiconductor alloy below that of amorphous silicon, and also utilizing sufficient amounts of the aforesaid electron donor dopant to maintain the amorphous silicon alloy as an n-type semiconductor.

  2. Wide band gap semiconductor templates

    DOE Patents [OSTI]

    Arendt, Paul N. (Los Alamos, NM); Stan, Liliana (Los Alamos, NM); Jia, Quanxi (Los Alamos, NM); DePaula, Raymond F. (Santa Fe, NM); Usov, Igor O. (Los Alamos, NM)

    2010-12-14T23:59:59.000Z

    The present invention relates to a thin film structure based on an epitaxial (111)-oriented rare earth-Group IVB oxide on the cubic (001) MgO terminated surface and the ion-beam-assisted deposition ("IBAD") techniques that are amendable to be over coated by semiconductors with hexagonal crystal structures. The IBAD magnesium oxide ("MgO") technology, in conjunction with certain template materials, is used to fabricate the desired thin film array. Similarly, IBAD MgO with appropriate template layers can be used for semiconductors with cubic type crystal structures.

  3. Toward Photochemical Water Splitting Using Band-Gap-Narrowed Semiconductors and Transition-Metal Based Molecular Catalysts

    SciTech Connect (OSTI)

    Muckerman,J.T.; Rodriguez, J.A.; Fujita, E.

    2009-06-07T23:59:59.000Z

    We are carrying out coordinated theoretical and experimental studies of toward photochemical water splitting using band-gap-narrowed semiconductors (BGNSCs) with attached multi-electron molecular water oxidation and hydrogen production catalysts. We focus on the coupling between the materials properties and the H{sub 2}O redox chemistry, with an emphasis on attaining a fundamental understanding of the individual elementary steps in the following four processes: (1) Light-harvesting and charge-separation of stable oxide or oxide-derived semiconductors for solar-driven water splitting, including the discovery and characterization of the behavior of such materials at the aqueous interface; (2) The catalysis of the four-electron water oxidation by dinuclear hydroxo transition-metal complexes with quinonoid ligands, and the rational search for improved catalysts; (3) Transfer of the design principles learned from the elucidation of the DuBois-type hydrogenase model catalysts in acetonitrile to the rational design of two-electron hydrogen production catalysts for aqueous solution; (4) Combining these three elements to examine the function of oxidation catalysts on BGNSC photoanode surfaces and hydrogen production catalysts on cathode surfaces at the aqueous interface to understand the challenges to the efficient coupling of the materials functions.

  4. Band gap engineering at a semiconductor - crystalline oxide interface

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

    Moghadam, Jahangir-Moghadam; Shen, Xuan; Chrysler, Matthew; Ahmadi-Majlan, Kamyar; Su, Dong; Ngai, Joseph H.

    2015-03-01T23:59:59.000Z

    The epitaxial growth of crystalline oxides on semiconductors provides a pathway to introduce new functionalities to semiconductor devices. Key to integrating the functionalities of oxides onto semiconductors is controlling the band alignment at interfaces between the two materials. Here we apply principles of band gap engineering traditionally used at heterojunctions between conventional semiconductors to control the band offset between a single crystalline oxide and a semiconductor. Reactive molecular beam epitaxy is used to realize atomically abrupt and structurally coherent interfaces between SrZrxTi1-xO? and Ge, in which the band gap of the former is enhanced with Zr content x. We presentmore »structural and electrical characterization of SrZrxTi1-xO?-Ge heterojunctions and demonstrate a type-I band offset can be achieved. These results demonstrate that band gap engineering can be exploited to realize functional semiconductor crystalline oxide heterojunctions.« less

  5. Implications of mercury interactions with band-gap semiconductor oxides

    SciTech Connect (OSTI)

    Granite, E.J.; King, W.P.; Stanko, D.C.; Pennline, H.W.

    2008-09-01T23:59:59.000Z

    Titanium dioxide is a well-known photooxidation catalyst. It will oxidize mercury in the presence of ultraviolet light from the sun and oxygen and/or moisture to form mercuric oxide. Several companies manufacture self-cleaning windows. These windows have a transparent coating of titanium dioxide. The titanium dioxide is capable of destroying organic contaminants in air in the presence of ultraviolet light from the sun, thereby keeping the windows clean. The commercially available self-cleaning windows were used to sequester mercury from oxygen–nitrogen mixtures. Samples of the self-cleaning glass were placed into specially designed photo-reactors in order to study the removal of elemental mercury from oxygen–nitrogen mixtures resembling air. The possibility of removing mercury from ambient air with a self-cleaning glass apparatus is examined. The intensity of 365-nm ultraviolet light was similar to the natural intensity from sunlight in the Pittsburgh region. Passive removal of mercury from the air may represent an option in lieu of, or in addition to, point source clean-up at combustion facilities. There are several common band-gap semiconductor oxide photocatalysts. Sunlight (both the ultraviolet and visible light components) and band-gap semiconductor particles may have a small impact on the global cycle of mercury in the environment. The potential environmental consequences of mercury interactions with band-gap semiconductor oxides are discussed. Heterogeneous photooxidation might impact the global transport of elemental mercury emanating from flue gases.

  6. Calculation of semiconductor band gaps with the M06-L density functional Yan Zhao and Donald G. Truhlara

    E-Print Network [OSTI]

    Truhlar, Donald G

    2009 The performance of the M06-L density functional has been tested for band gaps in seven,13 that is designed for main group thermo- chemistry, transition metal bonding, thermochemical kinet- ics in group-4, group 3­5, and metal oxide semiconductors. In Sec. II, we describe the test sets

  7. Transport band gap opening at metal–organic interfaces

    SciTech Connect (OSTI)

    Haidu, Francisc, E-mail: francisc.haidu@physik.tu-chemnitz.de; Salvan, Georgeta; Zahn, Dietrich R. T. [Semiconductor Physics, Technische Universität Chemnitz, D-09107 Chemnitz (Germany); Smykalla, Lars; Hietschold, Michael [Solid Surfaces Analysis, Technische Universität Chemnitz, D-09107 Chemnitz (Germany); Knupfer, Martin [Electronic and Optical Properties Department, IFW Dresden, D-01171 Dresden (Germany)

    2014-07-01T23:59:59.000Z

    The interface formation between copper phthalocyanine (CuPc) and two representative metal substrates, i.e., Au and Co, was investigated by the combination of ultraviolet photoelectron spectroscopy and inverse photoelectron spectroscopy. The occupied and unoccupied molecular orbitals and thus the transport band gap of CuPc are highly influenced by film thickness, i.e., molecule substrate distance. Due to the image charge potential given by the metallic substrates the transport band gap of CuPc “opens” from (1.4?±?0.3) eV for 1?nm thickness to (2.2?±?0.3) eV, and saturates at this value above 10?nm CuPc thickness. The interface dipoles with values of 1.2?eV and 1.0?eV for Au and Co substrates, respectively, predominantly depend on the metal substrate work functions. X-ray photoelectron spectroscopy measurements using synchrotron radiation provide detailed information on the interaction between CuPc and the two metal substrates. While charge transfer from the Au or Co substrate to the Cu metal center is present only at sub-monolayer coverages, the authors observe a net charge transfer from the molecule to the Co substrate for films in the nm range. Consequently, the Fermi level is shifted as in the case of a p-type doping of the molecule. This is, however, a competing phenomenon to the energy band shifts due to the image charge potential.

  8. Catalyzed Water Oxidation by Solar Irradiation of Band-Gap-Narrowed Semiconductors (Part 1. Overview).

    SciTech Connect (OSTI)

    Fujita,E.; Khalifah, P.; Lymar, S.; Muckerman, J.T.; Rodgriguez, J.

    2008-03-18T23:59:59.000Z

    The objectives of this report are: (1) Investigate the catalysis of water oxidation by cobalt and manganese hydrous oxides immobilized on titania or silica nanoparticles, and dinuclear metal complexes with quinonoid ligands in order to develop a better understanding of the critical water oxidation chemistry, and rationally search for improved catalysts. (2) Optimize the light-harvesting and charge-separation abilities of stable semiconductors including both a focused effort to improve the best existing materials by investigating their structural and electronic properties using a full suite of characterization tools, and a parallel effort to discover and characterize new materials. (3) Combine these elements to examine the function of oxidation catalysts on Band-Gap-Narrowed Semiconductor (BGNSC) surfaces and elucidate the core scientific challenges to the efficient coupling of the materials functions.

  9. Method of manufacturing flexible metallic photonic band gap structures, and structures resulting therefrom

    DOE Patents [OSTI]

    Gupta, Sandhya (Bloomington, MN); Tuttle, Gary L. (Ames, IA); Sigalas, Mihail (Ames, IA); McCalmont, Jonathan S. (Ames, IA); Ho, Kai-Ming (Ames, IA)

    2001-08-14T23:59:59.000Z

    A method of manufacturing a flexible metallic photonic band gap structure operable in the infrared region, comprises the steps of spinning on a first layer of dielectric on a GaAs substrate, imidizing this first layer of dielectric, forming a first metal pattern on this first layer of dielectric, spinning on and imidizing a second layer of dielectric, and then removing the GaAs substrate. This method results in a flexible metallic photonic band gap structure operable with various filter characteristics in the infrared region. This method may be used to construct multi-layer flexible metallic photonic band gap structures. Metal grid defects and dielectric separation layer thicknesses are adjusted to control filter parameters.

  10. Fermion space charge in narrow-band gap semiconductors, Weyl semimetals and around highly charged nuclei

    E-Print Network [OSTI]

    Eugene B. Kolomeisky; Joseph P. Straley; Hussain Zaidi

    2013-10-15T23:59:59.000Z

    The field of charged impurities in narrow-band gap semiconductors and Weyl semimetals can create electron-hole pairs when the total charge $Ze$ of the impurity exceeds a value $Z_{c}e$. The particles of one charge escape to infinity, leaving a screening space charge. The result is that the observable dimensionless impurity charge $Q_{\\infty}$ is less than $Z$ but greater than $Z_{c}$. There is a corresponding effect for nuclei with $Z >Z_{c} \\approx 170$, however in the condensed matter setting we find $Z_{c} \\simeq 10$. Thomas-Fermi theory indicates that $Q_{\\infty} = 0$ for the Weyl semimetal, but we argue that this is a defect of the theory. For the case of a highly-charged recombination center in a narrow band-gap semiconductor (or of a supercharged nucleus), the observable charge takes on a nearly universal value. In Weyl semimetals the observable charge takes on the universal value $Q_{\\infty} = Z_{c}$ set by the reciprocal of material's fine structure constant.

  11. Surface Plasmon Polariton Assisted Optical Switching in Noble Metal Nanoparticle Systems: A Sub-Band Gap Approach

    E-Print Network [OSTI]

    Dhara, S

    2015-01-01T23:59:59.000Z

    In a proposed book chapter surface plasmon polariton assisted optical switching in noble metal nanoparticle systems is discussed in the sub-band gap formalism.

  12. Band gap tuning in transition metal oxides by site-specific substitution

    DOE Patents [OSTI]

    Lee, Ho Nyung; Chisholm, Jr., Matthew F; Jellison, Jr., Gerald Earle; Singh, David J; Choi, Woo Seok

    2013-12-24T23:59:59.000Z

    A transition metal oxide insulator composition having a tuned band gap includes a transition metal oxide having a perovskite or a perovskite-like crystalline structure. The transition metal oxide includes at least one first element selected form the group of Bi, Ca, Ba, Sr, Li, Na, Mg, K, Pb, and Pr; and at least one second element selected from the group of Ti, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Rh, Hf, Ta, W, Re, Os, Ir, and Pt. At least one correlated insulator is integrated into the crystalline structure, including REMO.sub.3, wherein RE is at least one Rare Earth element, and wherein M is at least one element selected from the group of Co, V, Cr, Ni, Mn, and Fe. The composition is characterized by a band gap of less of 4.5 eV.

  13. Waveguides in three-dimensional metallic photonic band-gap materials

    SciTech Connect (OSTI)

    Sigalas, M.M.; Biswas, R.; Ho, K.M.; Soukoulis, C.M. [Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States)] [Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States); Crouch, D.D. [Advanced Electromagnetic Technologies Center, Raytheon Corporation, Rancho Cucamonga, California 91729 (United States)] [Advanced Electromagnetic Technologies Center, Raytheon Corporation, Rancho Cucamonga, California 91729 (United States)

    1999-08-01T23:59:59.000Z

    We theoretically investigate waveguide structures in three-dimensional metallic photonic band-gap (MPBG) materials. The MPBG materials used in this study consist of a three-dimensional mesh of metallic wires embedded in a dielectric. An {ital L}-shaped waveguide is created by removing part of the metallic wires. Using finite difference time domain simulations, we found that an 85{percent} transmission efficiency can be achieved through the 90{degree} bend with just three unit cell thickness MPBG structures. thinsp {copyright} {ital 1999} {ital The American Physical Society}

  14. Wide-band-gap, alkaline-earth-oxide semiconductor and devices utilizing same

    DOE Patents [OSTI]

    Abraham, Marvin M. (Oak Ridge, TN); Chen, Yok (Oak Ridge, TN); Kernohan, Robert H. (Oak Ridge, TN)

    1981-01-01T23:59:59.000Z

    This invention relates to novel and comparatively inexpensive semiconductor devices utilizing semiconducting alkaline-earth-oxide crystals doped with alkali metal. The semiconducting crystals are produced by a simple and relatively inexpensive process. As a specific example, a high-purity lithium-doped MgO crystal is grown by conventional techniques. The crystal then is heated in an oxygen-containing atmosphere to form many [Li].degree. defects therein, and the resulting defect-rich hot crystal is promptly quenched to render the defects stable at room temperature and temperatures well above the same. Quenching can be effected conveniently by contacting the hot crystal with room-temperature air.

  15. SPECTROSCOPIE DE DEFAUTS -LUMINESCENCE I. THE ANALYSIS OF WIDE BAND GAP SEMICONDUCTORS

    E-Print Network [OSTI]

    Boyer, Edmond

    on analysis depend very much on the device. In semiconductors, light emitting diodes (LEDs) are formed from pn

  16. Blueshift of optical band gap in ZnO thin films grown by metal-organic chemical-vapor deposition

    E-Print Network [OSTI]

    . INTRODUCTION Zinc oxide ZnO is a wide direct band-gap 3.37 eV semiconductor with a broad range of applications. Dimethylzinc DMZn , N2 gas, and high-purity O2 were used as the zinc source, carrier gas, and oxidizing agent including light-emitting devices,1 varistors,2 solar cells,3 and gas sensors.4 Moreover, ZnO is a promising

  17. Substrate-Induced Band-Gap Opening in Epitaxial Graphene

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

    Substrate-Induced Band-Gap Opening in Epitaxial Graphene Print Prospective challengers to silicon, the long-reigning king of semiconductors for computer chips and other electronic...

  18. Lattice matched semiconductor growth on crystalline metallic substrates

    DOE Patents [OSTI]

    Norman, Andrew G; Ptak, Aaron J; McMahon, William E

    2013-11-05T23:59:59.000Z

    Methods of fabricating a semiconductor layer or device and said devices are disclosed. The methods include but are not limited to providing a metal or metal alloy substrate having a crystalline surface with a known lattice parameter (a). The methods further include growing a crystalline semiconductor alloy layer on the crystalline substrate surface by coincident site lattice matched epitaxy. The semiconductor layer may be grown without any buffer layer between the alloy and the crystalline surface of the substrate. The semiconductor alloy may be prepared to have a lattice parameter (a') that is related to the lattice parameter (a). The semiconductor alloy may further be prepared to have a selected band gap.

  19. Fabrication of photonic band gap materials

    DOE Patents [OSTI]

    Constant, Kristen (Ames, IA); Subramania, Ganapathi S. (Ames, IA); Biswas, Rana (Ames, IA); Ho, Kai-Ming (Ames, IA)

    2002-01-15T23:59:59.000Z

    A method for forming a periodic dielectric structure exhibiting photonic band gap effects includes forming a slurry of a nano-crystalline ceramic dielectric or semiconductor material and monodisperse polymer microspheres, depositing a film of the slurry on a substrate, drying the film, and calcining the film to remove the polymer microspheres therefrom. The film may be cold-pressed after drying and prior to calcining. The ceramic dielectric or semiconductor material may be titania, and the polymer microspheres may be polystyrene microspheres.

  20. Conduction properties of metal/organic monolayer/semiconductor heterostructures

    SciTech Connect (OSTI)

    Li, D.; Bishop, A.; Gim, Y.; Shi, X.B.; Fitzsimmons, M.R.; Jia, Q.X. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1998-11-01T23:59:59.000Z

    We have fabricated and characterized rectifying devices made of metal/organic monolayer/semiconductor heterostructures. The devices consist of an organic barrier layer sandwiched between an aluminum (Al) metal contact and a {ital p}-type Si semiconductor. The barrier materials were chosen from three types of self-assembled monolayers (SAMs) with different electronic properties: (1) wide-band gap poly(diallydimethyl ammonium) chloride (PDDA), (2) narrow-band gap PDDA/NiPc (nickel phthalocyanine tetrasulfonate), and (3) donor type PDDA/PPP (poly {ital p}-quaterphenylene-disulfonic-dicarboxylic acid). From current{endash}voltage (I{endash}V) measurements at room temperature, we have found the turn-on voltage of the devices can be tuned by varying the structure, hence electronic properties, of the organic monolayers, and that there exists a power-law dependence of {ital I} on V, I{proportional_to}V{sup {alpha}}, with the exponent {alpha}=2.2 for PDDA, 2.7 for PDDA/NiPc, and 1.44 for PDDA/PPP as the barrier layer, respectively. Our results imply that the transport properties are controlled by both the electronic properties of the SAMs and those of the metal and semiconductor, as indicated by the power-law dependence of the I{endash}V characteristics. {copyright} {ital 1998 American Institute of Physics.}

  1. Narrow energy band gap gallium arsenide nitride semi-conductors and an ion-cut-synthesis method for producing the same

    DOE Patents [OSTI]

    Weng, Xiaojun; Goldman, Rachel S.

    2006-06-06T23:59:59.000Z

    A method for forming a semi-conductor material is provided that comprises forming a donor substrate constructed of GaAs, providing a receiver substrate, implanting nitrogen into the donor substrate to form an implanted layer comprising GaAs and nitrogen. The implanted layer is bonded to the receiver substrate and annealed to form GaAsN and nitrogen micro-blisters in the implanted layer. The micro-blisters allow the implanted layer to be cleaved from the donor substrate.

  2. Low band gap polymers Organic Photovoltaics

    E-Print Network [OSTI]

    Low band gap polymers for Organic Photovoltaics Eva Bundgaard Ph.D. Dissertation Risø National Bundgaard Title: Low band gap polymers for Organic photovoltaics Department: The polymer department Report the area of organic photovoltaics are focusing on low band gap polymers, a type of polymer which absorbs

  3. Photonic band gap structure simulator

    DOE Patents [OSTI]

    Chen, Chiping; Shapiro, Michael A.; Smirnova, Evgenya I.; Temkin, Richard J.; Sirigiri, Jagadishwar R.

    2006-10-03T23:59:59.000Z

    A system and method for designing photonic band gap structures. The system and method provide a user with the capability to produce a model of a two-dimensional array of conductors corresponding to a unit cell. The model involves a linear equation. Boundary conditions representative of conditions at the boundary of the unit cell are applied to a solution of the Helmholtz equation defined for the unit cell. The linear equation can be approximated by a Hermitian matrix. An eigenvalue of the Helmholtz equation is calculated. One computation approach involves calculating finite differences. The model can include a symmetry element, such as a center of inversion, a rotation axis, and a mirror plane. A graphical user interface is provided for the user's convenience. A display is provided to display to a user the calculated eigenvalue, corresponding to a photonic energy level in the Brilloin zone of the unit cell.

  4. Variation in band gap of lanthanum chromate by transition metals doping LaCr{sub 0.9}A{sub 0.1}O{sub 3} (A:Fe/Co/Ni)

    SciTech Connect (OSTI)

    Naseem, Swaleha, E-mail: wasiamu@gmail.com; Khan, Wasi, E-mail: wasiamu@gmail.com; Saad, A. A., E-mail: wasiamu@gmail.com; Shoeb, M., E-mail: wasiamu@gmail.com; Ahmed, Hilal, E-mail: wasiamu@gmail.com; Naqvi, A. H. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg. and Technology, Aligarh Muslim University, Aligarh-202002 (India); Husain, Shahid [Department of Physics, Aligarh Muslim University, Aligarh-202002 (India)

    2014-04-24T23:59:59.000Z

    Transition metal (Fe, Co, Ni) doped lanthanum chromate (LaCrO{sub 3}) nanoparticles (NPs) were prepared by gel combustion method and calcinated at 800°C. Microstructural studies were carried by XRD and SEM/EDS techniques. The results of structural characterization show the formation of all samples in single phase without any impurity. Optical properties were studied by UV- visible and photoluminescence techniques. The energy band gap was calculated and the variation was observed with the doping of transition metal ions. Photoluminescence spectra show the emission peak maxima for the pure LaCrO{sub 3} at about 315 nm. Influence of Fe, Co, Ni doping was studied and compared with pure lanthanum chromate nanoparticles.

  5. Magnetization dynamics and spin diffusion in semiconductors and metals

    E-Print Network [OSTI]

    Cywi?ski, ?ukasz

    2007-01-01T23:59:59.000Z

    to (III,Mn)V ferromagnetic semiconductors . . . . . . . . .semiconductors . . . . . . . . . . . . . . . . . .Spin di?usion in semiconductors and metals: a general

  6. Voltage-matched, monolithic, multi-band-gap devices

    SciTech Connect (OSTI)

    Wanlass, Mark W.; Mascarenhas, Angelo

    2006-08-22T23:59:59.000Z

    Monolithic, tandem, photonic cells include at least a first semiconductor layer and a second semiconductor layer, wherein each semiconductor layer includes an n-type region, a p-type region, and a given band-gap energy. Formed within each semiconductor layer is a sting of electrically connected photonic sub-cells. By carefully selecting the numbers of photonic sub-cells in the first and second layer photonic sub-cell string(s), and by carefully selecting the manner in which the sub-cells in a first and second layer photonic sub-cell string(s) are electrically connected, each of the first and second layer sub-cell strings may be made to achieve one or more substantially identical electrical characteristics.

  7. Voltage-Matched, Monolithic, Multi-Band-Gap Devices

    DOE Patents [OSTI]

    Wanlass, M. W.; Mascarenhas, A.

    2006-08-22T23:59:59.000Z

    Monolithic, tandem, photonic cells include at least a first semiconductor layer and a second semiconductor layer, wherein each semiconductor layer includes an n-type region, a p-type region, and a given band-gap energy. Formed within each semiconductor layer is a string of electrically connected photonic sub-cells. By carefully selecting the numbers of photonic sub-cells in the first and second layer photonic sub-cell string(s), and by carefully selecting the manner in which the sub-cells in a first and second layer photonic sub-cell string(s) are electrically connected, each of the first and second layer sub-cell strings may be made to achieve one or more substantially identical electrical characteristics.

  8. Band-Gap Engineering of Carbon Nanotubes with Grain Boundaries...

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

    Band-Gap Engineering of Carbon Nanotubes with Grain Boundaries. Band-Gap Engineering of Carbon Nanotubes with Grain Boundaries. Abstract: Structure and electronic properties of...

  9. Indirect-direct band gap transition through electric tuning in bilayer MoS{sub 2}

    SciTech Connect (OSTI)

    Zhang, Z. Y.; Si, M. S., E-mail: sims@lzu.edu.cn; Wang, Y. H.; Gao, X. P. [Key laboratory for Magnetism and Magnetic Materials of the Ministry of Education, School of Physical Science and Technology, Lanzhou University, Lanzhou 730 000 (China)] [Key laboratory for Magnetism and Magnetic Materials of the Ministry of Education, School of Physical Science and Technology, Lanzhou University, Lanzhou 730 000 (China); Sung, Dongchul; Hong, Suklyun [Graphene Research Institute, Sejong University, Seoul 143 747 (Korea, Republic of)] [Graphene Research Institute, Sejong University, Seoul 143 747 (Korea, Republic of); He, Junjie [Department of Physics, Xiangtan University, Hunan 411 105 (China)] [Department of Physics, Xiangtan University, Hunan 411 105 (China)

    2014-05-07T23:59:59.000Z

    We investigate the electronic properties of bilayer MoS{sub 2} exposed to an external electric field by using first-principles calculations. It is found that a larger interlayer distance, referring to that by standard density functional theory (DFT) with respect to that by DFT with empirical dispersion corrections, makes indirect-direct band gap transition possible by electric control. We show that external electric field effectively manipulates the valence band contrast between the K- and ?-valleys by forming built-in electric dipole fields, which realizes an indirect-direct transition before a semiconductor-metal transition happens. Our results provide a novel efficient access to tune the electronic properties of two-dimensional layered materials.

  10. Optical properties of two-dimensional transition metal dichalcogenides

    E-Print Network [OSTI]

    Lin, Yuxuan, S.M. Massachusetts Institute of Technology

    2014-01-01T23:59:59.000Z

    The re-discovery of the atomically thin transition metal dichalcogenides (TMDs), which are mostly semiconductors with a wide range of band gaps, has diversified the family of two-dimensional materials and boosted the ...

  11. Substrate-Induced Band-Gap Opening in Epitaxial Graphene

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

    Substrate-Induced Band-Gap Opening in Epitaxial Graphene Substrate-Induced Band-Gap Opening in Epitaxial Graphene Print Wednesday, 26 March 2008 00:00 Prospective challengers to...

  12. Direct band gap narrowing in highly doped Ge

    E-Print Network [OSTI]

    Han, Zhaohong

    Direct band gap narrowing in highly doped n-type Ge is observed through photoluminescence measurements by determining the spectrum peak shift. A linear relationship between the direct band gap emission and carrier concentration ...

  13. Hydrogenated Graphene Nanoflakes: Semiconductor to Half-Metal...

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

    Hydrogenated Graphene Nanoflakes: Semiconductor to Half-Metal Transition and Remarkable Large Magnetism. Hydrogenated Graphene Nanoflakes: Semiconductor to Half-Metal Transition...

  14. acoustic band gaps: Topics by E-print Network

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

    type of phononic crystals manufactured Institute of Physics. DOI: 10.10631.2167794 The propagation of acoustic waves in periodic composite Deymier, Pierre 2 Acoustic band gap...

  15. Energy Band-Gap Engineering of Graphene Nanoribbons Melinda Y. Han,1

    E-Print Network [OSTI]

    Kim, Philip

    , New York, New York 10027, USA 2 Department of Physics, Columbia University, New York, New York 10027Energy Band-Gap Engineering of Graphene Nanoribbons Melinda Y. Han,1 Barbaros O¨ zyilmaz,2 Yuanbo an energy gap near the charge neutrality point. Individual graphene layers are contacted with metal

  16. SEMIEMPIRICAL MOLECULAR ORBITAL CALCULATIONS OF BAND GAPS OF CONJUGATED POLYMERS

    E-Print Network [OSTI]

    Goddard III, William A.

    SEMI­EMPIRICAL MOLECULAR ORBITAL CALCULATIONS OF BAND GAPS OF CONJUGATED POLYMERS Tahir Cagin Research and Development Center, Materials Labarotory, Polymer Branch, Wright Patterson AFB, Ohio 45433 geometries and energy band gaps of conjugated polymers. In this study, we used a modified version of semi

  17. Fabrication of Ceramic Layer-by-Layer Infrared Wavelength Photonic Band Gap Crystals

    SciTech Connect (OSTI)

    Henry Hao-Chuan Kang

    2004-12-19T23:59:59.000Z

    Photonic band gap (PBG) crystals, also known as photonic crystals, are periodic dielectric structures which form a photonic band gap that prohibit the propagation of electromagnetic (EM) waves of certain frequencies at any incident angles. Photonic crystals have several potential applications including zero-threshold semiconductor lasers, the inhibition of spontaneous emission, dielectric mirrors, and wavelength filters. If defect states are introduced in the crystals, light can be guided from one location to another or even a sharp bending of light in micron scale can be achieved. This generates the potential for optical waveguide and optical circuits, which will contribute to the improvement in the fiber-optic communications and the development of high-speed computers.

  18. Feasibility of band gap engineering of pyrite FeS?

    E-Print Network [OSTI]

    Sun, Ruoshi

    We use first-principles computations to investigate whether the band gap of pyrite FeS? can be increased by alloying in order to make it a more effective photovoltaic material. In addition to the isostructural compounds ...

  19. Substrate-induced band gap opening in epitaxial graphene

    E-Print Network [OSTI]

    2008-01-01T23:59:59.000Z

    H.A. Electronic states of graphene nanoribbons studied withS.G. Louie. Energy gaps in graphene nanoribbons. Phys. Rev.band-gap engineering of graphene nanoribbons. Phys. Rev.

  20. Characterization of Novel Semiconductor Alloys for Band Gap Engineering

    E-Print Network [OSTI]

    Broesler, Robert Joseph

    2010-01-01T23:59:59.000Z

    including high efficiency photovoltaics and light emittingEngineering 1.2.1 High Efficiency Photovoltaics 1.2.2 High1.2.1 High Efficiency Photovoltaics There has been

  1. Characterization of Novel Semiconductor Alloys for Band Gap Engineering

    E-Print Network [OSTI]

    Broesler, Robert Joseph

    2010-01-01T23:59:59.000Z

    and pulsed laser melting (PLM) to crystallize the amorphousrich crystalline phases, where as PLM results in GaAs-richFurther study into the effects of PLM on amorphous GaNAs is

  2. Recent emission channeling studies in wide band gap semiconductors

    E-Print Network [OSTI]

    Wahl, Ulrich; Rita, E; Alves, E; Carvalho-Soares, João; De Vries, Bart; Matias, V; Vantomme, A

    2005-01-01T23:59:59.000Z

    We present results of recent emission channeling experiments on the lattice location of implanted Fe and rare earths in wurtzite GaN and ZnO. In both cases the majority of implanted atoms are found on substitutional cation sites. The root mean square displacements from the ideal substitutional Ga and Zn sites are given and the stability of the Fe and rare earth lattice location against thermal annealing is discussed.

  3. First principles study of Fe in diamond: A diamond-based half metallic dilute magnetic semiconductor

    SciTech Connect (OSTI)

    Benecha, E. M. [Department of Physics, University of South Africa, P.O. Box 392, UNISA 0003 Pretoria (South Africa); Lombardi, E. B., E-mail: lombaeb@unisa.ac.za [College of Graduate Studies, University of South Africa, P.O. Box 392, UNISA 0003 Pretoria (South Africa)

    2013-12-14T23:59:59.000Z

    Half-metallic ferromagnetic ordering in semiconductors, essential in the emerging field of spintronics for injection and transport of highly spin polarised currents, has up to now been considered mainly in III–V and II–VI materials. However, low Curie temperatures have limited implementation in room temperature device applications. We report ab initio Density Functional Theory calculations on the properties of Fe in diamond, considering the effects of lattice site, charge state, and Fermi level position. We show that the lattice sites and induced magnetic moments of Fe in diamond depend strongly on the Fermi level position and type of diamond co-doping, with Fe being energetically most favorable at the substitutional site in p-type and intrinsic diamond, while it is most stable at a divacancy site in n-type diamond. Fe induces spin polarized bands in the band gap, with strong hybridization between Fe-3d and C-2s,2p bands. We further consider Fe-Fe spin interactions in diamond and show that substitutional Fe{sup +1} in p-type diamond exhibits a half-metallic character, with a magnetic moment of 1.0??{sub B} per Fe atom and a large ferromagnetic stabilization energy of 33?meV, an order of magnitude larger than in other semiconductors, with correspondingly high Curie temperatures. These results, combined with diamond's unique properties, demonstrate that Fe doped p-type diamond is likely to be a highly suitable candidate material for spintronics applications.

  4. Band gap engineering strategy via polarization rotation in perovskite ferroelectrics

    SciTech Connect (OSTI)

    Wang, Fenggong, E-mail: fenggong@sas.upenn.edu; Grinberg, Ilya; Rappe, Andrew M., E-mail: rappe@sas.upenn.edu [The Makineni Theoretical Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104–6323 (United States)

    2014-04-14T23:59:59.000Z

    We propose a strategy to engineer the band gaps of perovskite oxide ferroelectrics, supported by first principles calculations. We find that the band gaps of perovskites can be substantially reduced by as much as 1.2?eV through local rhombohedral-to-tetragonal structural transition. Furthermore, the strong polarization of the rhombohedral perovskite is largely preserved by its tetragonal counterpart. The B-cation off-center displacements and the resulting enhancement of the antibonding character in the conduction band give rise to the wider band gaps of the rhombohedral perovskites. The correlation between the structure, polarization orientation, and electronic structure lays a good foundation for understanding the physics of more complex perovskite solid solutions and provides a route for the design of photovoltaic perovskite ferroelectrics.

  5. Special purpose modes in photonic band gap fibers

    DOE Patents [OSTI]

    Spencer, James; Noble, Robert; Campbell, Sara

    2013-04-02T23:59:59.000Z

    Photonic band gap fibers are described having one or more defects suitable for the acceleration of electrons or other charged particles. Methods and devices are described for exciting special purpose modes in the defects including laser coupling schemes as well as various fiber designs and components for facilitating excitation of desired modes. Results are also presented showing effects on modes due to modes in other defects within the fiber and due to the proximity of defects to the fiber edge. Techniques and devices are described for controlling electrons within the defect(s). Various applications for electrons or other energetic charged particles produced by such photonic band gap fibers are also described.

  6. Transformation Optics with Photonic Band Gap Media

    E-Print Network [OSTI]

    Urzhumov, Yaroslav A

    2010-01-01T23:59:59.000Z

    We introduce a class of optical media based on adiabatically modulated, dielectric-only, and potentially extremely low-loss, photonic crystals. The media we describe represent a generalization of the eikonal limit of transformation optics (TO). The foundation of the concept is the possibility to fit frequency isosurfaces in the k-space of photonic crystals with elliptic surfaces, allowing them to mimic the dispersion relation of light in anisotropic effective media. Photonic crystal cloaks and other TO devices operating at visible wavelengths can be constructed from optically transparent substances like glasses, whose attenuation coefficient can be as small as 10 dB/km, suggesting the TO design methodology can be applied to the development of optical devices not limited by the losses inherent to metal-based, passive metamaterials.

  7. Method of physical vapor deposition of metal oxides on semiconductors

    DOE Patents [OSTI]

    Norton, David P. (Knoxville, TN)

    2001-01-01T23:59:59.000Z

    A process for growing a metal oxide thin film upon a semiconductor surface with a physical vapor deposition technique in a high-vacuum environment and a structure formed with the process involves the steps of heating the semiconductor surface and introducing hydrogen gas into the high-vacuum environment to develop conditions at the semiconductor surface which are favorable for growing the desired metal oxide upon the semiconductor surface yet is unfavorable for the formation of any native oxides upon the semiconductor. More specifically, the temperature of the semiconductor surface and the ratio of hydrogen partial pressure to water pressure within the vacuum environment are high enough to render the formation of native oxides on the semiconductor surface thermodynamically unstable yet are not so high that the formation of the desired metal oxide on the semiconductor surface is thermodynamically unstable. Having established these conditions, constituent atoms of the metal oxide to be deposited upon the semiconductor surface are directed toward the surface of the semiconductor by a physical vapor deposition technique so that the atoms come to rest upon the semiconductor surface as a thin film of metal oxide with no native oxide at the semiconductor surface/thin film interface. An example of a structure formed by this method includes an epitaxial thin film of (001)-oriented CeO.sub.2 overlying a substrate of (001) Ge.

  8. Photonic-band-gap properties for two-component slow light

    SciTech Connect (OSTI)

    Ruseckas, J.; Kudriasov, V.; Juzeliunas, G.; Unanyan, R. G.; Otterbach, J.; Fleischhauer, M. [Institute of Theoretical Physics and Astronomy, Vilnius University, A. Gostauto 12, Vilnius 01108 (Lithuania); Fachbereich Physik and Research Center OPTIMAS, Technische Universitaet Kaiserslautern, Kaiserslautern D-67663 (Germany)

    2011-06-15T23:59:59.000Z

    We consider two-component ''spinor'' slow light in an ensemble of atoms coherently driven by two pairs of counterpropagating control laser fields in a double tripod-type linkage scheme. We derive an equation of motion for the spinor slow light (SSL) representing an effective Dirac equation for a massive particle with the mass determined by the two-photon detuning. By changing the detuning the atomic medium acts as a photonic crystal with a controllable band gap. If the frequency of the incident probe light lies within the band gap, the light experiences reflection from the sample and can tunnel through it. For frequencies outside the band gap, the transmission and reflection probabilities oscillate with the increasing length of the sample. In both cases the reflection takes place into the complementary mode of the probe field. We investigate the influence of the finite excited state lifetime on the transmission and reflection coefficients of the probe light. We discuss possible experimental implementations of the SSL using alkali-metal atoms such as rubidium or sodium.

  9. Metal Oxide Semiconductor Nanoparticles Open the Door to New...

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

    Innovations Technology available for licensing: novel nanometer-sized metal oxide semiconductors that allow targeting, initiating and control of in vitro and in vivo chemical...

  10. Multi-junction, monolithic solar cell using low-band-gap materials lattice matched to GaAs or Ge

    DOE Patents [OSTI]

    Olson, Jerry M. (Lakewood, CO); Kurtz, Sarah R. (Golden, CO); Friedman, Daniel J. (Lakewood, CO)

    2001-01-01T23:59:59.000Z

    A multi-junction, monolithic, photovoltaic solar cell device is provided for converting solar radiation to photocurrent and photovoltage with improved efficiency. The solar cell device comprises a plurality of semiconductor cells, i.e., active p/n junctions, connected in tandem and deposited on a substrate fabricated from GaAs or Ge. To increase efficiency, each semiconductor cell is fabricated from a crystalline material with a lattice constant substantially equivalent to the lattice constant of the substrate material. Additionally, the semiconductor cells are selected with appropriate band gaps to efficiently create photovoltage from a larger portion of the solar spectrum. In this regard, one semiconductor cell in each embodiment of the solar cell device has a band gap between that of Ge and GaAs. To achieve desired band gaps and lattice constants, the semiconductor cells may be fabricated from a number of materials including Ge, GaInP, GaAs, GaInAsP, GaInAsN, GaAsGe, BGaInAs, (GaAs)Ge, CuInSSe, CuAsSSe, and GaInAsNP. To further increase efficiency, the thickness of each semiconductor cell is controlled to match the photocurrent generated in each cell. To facilitate photocurrent flow, a plurality of tunnel junctions of low-resistivity material are included between each adjacent semiconductor cell. The conductivity or direction of photocurrent in the solar cell device may be selected by controlling the specific p-type or n-type characteristics for each active junction.

  11. Indirect-to-direct band gap transition in relaxed and strained Ge{sub 1?x?y}Si{sub x}Sn{sub y} ternary alloys

    SciTech Connect (OSTI)

    Attiaoui, Anis; Moutanabbir, Oussama [Department of Engineering Physics, École Polytechnique de Montréal, Montréal, C.P. 6079, Succ. Centre-Ville, Montréal, Québec H3C 3A7 (Canada)

    2014-08-14T23:59:59.000Z

    Sn-containing group IV semiconductors create the possibility to independently control strain and band gap thus providing a wealth of opportunities to develop an entirely new class of low dimensional systems, heterostructures, and silicon-compatible electronic and optoelectronic devices. With this perspective, this work presents a detailed investigation of the band structure of strained and relaxed Ge{sub 1?x?y}Si{sub x}Sn{sub y} ternary alloys using a semi-empirical second nearest neighbors tight binding method. This method is based on an accurate evaluation of the deformation potential constants of Ge, Si, and ?-Sn using a stochastic Monte-Carlo approach as well as a gradient based optimization method. Moreover, a new and efficient differential evolution approach is also developed to accurately reproduce the experimental effective masses and band gaps. Based on this, we elucidated the influence of lattice disorder, strain, and composition on Ge{sub 1?x?y}Si{sub x}Sn{sub y} band gap energy and directness. For 0???x???0.4 and 0???y???0.2, we found that tensile strain lowers the critical content of Sn needed to achieve a direct band gap semiconductor with the corresponding band gap energies below 0.76?eV. This upper limit decreases to 0.43?eV for direct gap, fully relaxed ternary alloys. The obtained transition to direct band gap is given by y?>?0.605?×?x?+?0.077 and y?>?1.364?×?x?+?0.107 for epitaxially strained and fully relaxed alloys, respectively. The effects of strain, at a fixed composition, on band gap directness were also investigated and discussed.

  12. Electronic structure of Pt based topological Heusler compounds with C1{sub b} structure and 'zero band gap'

    SciTech Connect (OSTI)

    Ouardi, Siham; Shekhar, Chandra; Fecher, Gerhard H.; Kozina, Xeniya; Stryganyuk, Gregory; Felser, Claudia [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitaet, D-55099 Mainz (Germany); Ueda, Shigenori; Kobayashi, Keisuke [NIMS Beamline Station at SPring-8, National Institute for Materials Science, Hyogo 679-5148 (Japan)

    2011-05-23T23:59:59.000Z

    Besides of their well-known wide range of properties it was recently shown that many of the heavy Heusler semiconductors with 1:1:1 composition and C1{sub b} structure exhibit a zero band gap behavior and are topological insulators induced by their inverted band structure. In the present study, the electronic structure of the Heusler compounds PtYSb and PtLaBi was investigated by bulk sensitive hard x-ray photoelectron spectroscopy. The measured valence band spectra are clearly resolved and in well agreement to the first-principles calculations of the electronic structure of the compounds. The experimental results give clear evidence for the zero band gap state.

  13. Wave propagation in ordered, disordered, and nonlinear photonic band gap materials

    SciTech Connect (OSTI)

    Lidorikis, Elefterios

    1999-12-10T23:59:59.000Z

    Photonic band gap materials are artificial dielectric structures that give the promise of molding and controlling the flow of optical light the same way semiconductors mold and control the electric current flow. In this dissertation the author studied two areas of photonic band gap materials. The first area is focused on the properties of one-dimensional PBG materials doped with Kerr-type nonlinear material, while, the second area is focused on the mechanisms responsible for the gap formation as well as other properties of two-dimensional PBG materials. He first studied, in Chapter 2, the general adequacy of an approximate structure model in which the nonlinearity is assumed to be concentrated in equally-spaced very thin layers, or 6-functions, while the rest of the space is linear. This model had been used before, but its range of validity and the physical reasons for its limitations were not quite clear yet. He performed an extensive examination of many aspects of the model's nonlinear response and comparison against more realistic models with finite-width nonlinear layers, and found that the d-function model is quite adequate, capturing the essential features in the transmission characteristics. The author found one exception, coming from the deficiency of processing a rigid bottom band edge, i.e. the upper edge of the gaps is always independent of the refraction index contrast. This causes the model to miss-predict that there are no soliton solutions for a positive Kerr-coefficient, something known to be untrue.

  14. Metal-doped semiconductor nanoparticles and methods of synthesis thereof

    DOE Patents [OSTI]

    Ren, Zhifeng (Newton, MA); Chen, Gang (Carlisle, MA); Poudel, Bed (West Newton, MA); Kumar, Shankar (Newton, MA); Wang, Wenzhong (Beijing, CN); Dresselhaus, Mildred (Arlington, MA)

    2009-09-08T23:59:59.000Z

    The present invention generally relates to binary or higher order semiconductor nanoparticles doped with a metallic element, and thermoelectric compositions incorporating such nanoparticles. In one aspect, the present invention provides a thermoelectric composition comprising a plurality of nanoparticles each of which includes an alloy matrix formed of a Group IV element and Group VI element and a metallic dopant distributed within the matrix.

  15. Single-junction solar cells with the optimum band gap for terrestrial concentrator applications

    DOE Patents [OSTI]

    Wanlass, Mark W. (Golden, CO)

    1994-01-01T23:59:59.000Z

    A single-junction solar cell having the ideal band gap for terrestrial concentrator applications. Computer modeling studies of single-junction solar cells have shown that the presence of absorption bands in the direct spectrum has the effect of "pinning" the optimum band gap for a wide range of operating conditions at a value of 1.14.+-.0.02 eV. Efficiencies exceeding 30% may be possible at high concentration ratios for devices with the ideal band gap.

  16. Surface Plasmon Band Gap Sensor A new sensor for robust on-field biosensing (SEN 1)

    E-Print Network [OSTI]

    Arnaud Benahmed; Robert Lam; Chih-Ming Ho

    2006-01-01T23:59:59.000Z

    Networked Sensing Surface Plasmon Band Gap Sensor A newsensing concept Nanostructures for Surface Plasmon SensingSurface Plasmon are surface EM waves whose wavelength is

  17. PHYSICAL REVIEW B 90, 115209 (2014) Computational search for direct band gap silicon crystals

    E-Print Network [OSTI]

    Lee, Jooyoung

    2014-01-01T23:59:59.000Z

    of microns thick, while solar cells made from direct band gap materials (such as CdTe, CIGS, or CZTS) can

  18. Thermoelectric power measurements of wide band gap semiconducting Chul-Ho Lee,1

    E-Print Network [OSTI]

    Kim, Philip

    Thermoelectric power measurements of wide band gap semiconducting nanowires Chul-Ho Lee,1 Gyu online 13 January 2009 We investigated the temperature-dependent thermoelectric power TEP of individual concentration in wide band gap semiconducting nano- wires employing temperature-dependent thermoelectric power

  19. Light trapping design for low band-gap polymer solar cells

    E-Print Network [OSTI]

    John, Sajeev

    Light trapping design for low band-gap polymer solar cells Stephen Foster1,* and Sajeev John1,2 1 demonstrate numerically a 2-D nanostructured design for light trapping in a low band-gap polymer solar cell observe an enhancement in solar absorption of almost 40% relative to a planar cell. Improvements

  20. Band gap changes of GaN shocked to 13 GPa M. D. McCluskeya)

    E-Print Network [OSTI]

    McCluskey, Matthew

    Band gap changes of GaN shocked to 13 GPa M. D. McCluskeya) and Y. M. Gupta Institute for Shock, California 94304 Received 24 October 2001; accepted for publication 19 December 2001 The band gap of GaN in shock-wave experiments. Shock waves were generated by impacting the GaN samples with c-cut sapphire

  1. Metal-sensing layer-semiconductor and metal-sensing layer-metal heterostructure gas sensors

    SciTech Connect (OSTI)

    O'Leary, M.; Li, Zheng; Fonash, S.J.

    1987-01-01T23:59:59.000Z

    Extremely sensitive gas sensors can be fabricated using heterostructures of the form metal-sensing layer-semiconductor or metal-sensing layer-metal. These structures are heterostructure diodes which have the barrier controlling transport at least partially located in the sensing layer. In the presence of the gas species to be detected, the electrical properties of the sensing layer evolve, resulting in a modification of the barrier to electric current transport and, hence, resulting in detection due to changes in the current-voltage characteristics of the device. This type of sensor structure is demonstrated using the Pd/Ti-O/sub x/Ti heterostructure hydrogen detector.

  2. Al-doped HfO2/In0.53Ga0.47As metal-oxide-semiconductor capaci

    E-Print Network [OSTI]

    Stemmer, Susanne

    2011-01-01T23:59:59.000Z

    MOS (Metal Oxide Semiconductor) Phys- ics and Technologywas funded by the Semiconductor Re- search Corporation0.47 As metal-oxide-semiconductor capacitors Yoontae Hwang,

  3. Significant Reduction in NiO Band Gap upon Formation of LixNi1?xO Alloys: Applications to Solar Energy Conversion

    SciTech Connect (OSTI)

    Alidoust, Nima; Toroker, Maytal; Keith, John A.; Carter, Emily A.

    2014-01-01T23:59:59.000Z

    Long-term sustainable solar energy conversion relies on identifying economical and versatile semiconductor materials with appropriate band structures for photovoltaic and photocatalytic applications (e.g., band gaps of ?1.5–2.0 eV). Nickel oxide (NiO) is an inexpensive yet highly promising candidate. Its charge-transfer character may lead to longer carrier lifetimes needed for higher efficiencies, and its conduction band edge is suitable for driving hydrogen evolution via water-splitting. However, NiO’s large band gap (?4 eV) severely limits its use in practical applications. Our first-principles quantum mechanics calculations show band gaps dramatically decrease to ?2.0 eV when NiO is alloyed with Li2O. We show that LixNi1?xO alloys (with x=0.125 and 0.25) are p-type semiconductors, contain states with no impurity levels in the gap and maintain NiO’s desirable charge-transfer character. Lastly, we show that the alloys have potential for photoelectrochemical applications, with band edges well-placed for photocatalytic hydrogen production and CO2 reduction, as well as in tandem dye-sensitized solar cells as a photocathode.

  4. Single-junction solar cells with the optimum band gap for terrestrial concentrator applications

    DOE Patents [OSTI]

    Wanlass, M.W.

    1994-12-27T23:59:59.000Z

    A single-junction solar cell is described having the ideal band gap for terrestrial concentrator applications. Computer modeling studies of single-junction solar cells have shown that the presence of absorption bands in the direct spectrum has the effect of ''pinning'' the optimum band gap for a wide range of operating conditions at a value of 1.14[+-]0.02 eV. Efficiencies exceeding 30% may be possible at high concentration ratios for devices with the ideal band gap. 7 figures.

  5. Calculation of wakefields in a 17 GHz beam-driven photonic band-gap accelerator structure

    E-Print Network [OSTI]

    Hu, Min

    We present the theoretical analysis and computer simulation of the wakefields in a 17 GHz photonic band-gap (PBG) structure for accelerator applications. Using the commercial code CST Particle Studio, the fundamental ...

  6. Tunable frequency band-gap and pulse propagation in a strongly nonlinear diatomic chain

    E-Print Network [OSTI]

    E. B. Herbold; J. Kim; V. F. Nesterenko; S. Wang; C. Daraio

    2008-06-26T23:59:59.000Z

    One-dimensional nonlinear phononic crystals have been assembled from periodic diatomic chains of stainless steel cylinders alternated with Polytetrafluoroethylene (PTFE) spheres. We report the presence of acoustic band gaps in the dispersion relation of the linearized systems and study the transformation of single and multiple pulses in linear, nonlinear and strongly nonlinear regimes with numerical calculations and experiments. The limiting frequencies of the band gap are within the audible frequency range (20-20,000 Hz) and can be tuned by varying the particle's material properties, mass and initial compression. Pulses rapidly transform within very short distances from the impacted end due to the influence of the band gap in the linear and in nonlinear elastic chains. The effects of an in situ band gap created by a mean dynamic compression are observed in the strongly nonlinear wave regime.

  7. Thermophotovoltaic conversion using selective infrared line emitters and large band gap photovoltaic devices

    DOE Patents [OSTI]

    Brandhorst, Jr., Henry W. (Auburn, AL); Chen, Zheng (Auburn, AL)

    2000-01-01T23:59:59.000Z

    Efficient thermophotovoltaic conversion can be performed using photovoltaic devices with a band gap in the 0.75-1.4 electron volt range, and selective infrared emitters chosen from among the rare earth oxides which are thermally stimulated to emit infrared radiation whose energy very largely corresponds to the aforementioned band gap. It is possible to use thermovoltaic devices operating at relatively high temperatures, up to about 300.degree. C., without seriously impairing the efficiency of energy conversion.

  8. Fabrication and characterization of metal-semiconductor-metal nanorod using template synthesis

    SciTech Connect (OSTI)

    Kim, Kyohyeok; Kwon, Namyong; Hong, Junki; Chung, Ilsub [Sungkyunkwan University Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Sungkyunkwan University Advanced Institute of Nanotechnology and Information and Communication Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2009-07-15T23:59:59.000Z

    The authors attempted to fabricate and characterize one dimensional metal-semiconductor-metal (MSM) nanorod using a template. Cadmium selenide (CdSe) and polypyrrole (Ppy) were chosen as n-type and p-type semiconductor materials, respectively, whereas Au was chosen as a metal electrode. The fabrication of the nanorod was achieved by ''template synthesis'' method using polycarbonate membrane. The structure of the fabricated nanorod was analyzed using scanning electron microscopy and energy dispersive spectroscopy. In addition, the electrical properties of MSM nanorods were characterized using scanning probe microscopy (Seiko Instruments, SPA 300 HV) by probing with a conductive cantilever. I-V characteristics as a function of the temperature give the activation energy, as well as the barrier height of a metal-semiconductor contact, which is useful to understand the conduction mechanism of MSM nanorods.

  9. Strain and electric field induced electronic properties of two-dimensional hybrid bilayers of transition-metal dichalcogenides

    SciTech Connect (OSTI)

    Sharma, Munish, E-mail: munishsharmahpu@live.com, E-mail: pk-ahluwalia7@yahoo.com; Kumar, Ashok; Ahluwalia, P. K., E-mail: munishsharmahpu@live.com, E-mail: pk-ahluwalia7@yahoo.com [Department of Physics, Himachal Pradesh University, Shimla 171005 (India); Pandey, Ravindra [Department of Physics, Michigan Technological University, Houghton, Michigan 49931 (United States)

    2014-08-14T23:59:59.000Z

    Tunability of the electronic properties of two-dimensional bilayer hetero structures of transition-metal dichalcogenides (i.e., MX{sub 2}-M?X?{sub 2} with (M, M??=?Mo, W; X, X??=?S, Se) is investigated. Application of both strain and electric field is found to modify the band gap and carrier effective mass in the hybrid bilayers considered. The calculated results based on density functional theory suggest that the tensile strain considerably changes the band gap of semiconducting bilayers; it makes the band gap to be indirect, and later initiates the semiconductor-to-metal transition. Application of the external electric fields, on the other hand, shows asymmetric variation in the band gap leading to the closure of the gap at about 0.5–1.0?V/Å. Tuning of the band gap and carrier effective mass in such a controlled manner makes the hybrid bilayers of transition metal dichalcogenides to be promising candidates for application in electronic devices at nanoscale.

  10. Science and applications of infrared semiconductor nanocrystals

    E-Print Network [OSTI]

    Geyer, Scott Mitchell

    2010-01-01T23:59:59.000Z

    In this work we study several applications of semiconductor nanocrystals (NCs) with infrared band gaps. In the first half, we explore the physics of two systems with applications in NC based photovoltaics. The physics of ...

  11. Band gap engineering for graphene by using Na{sup +} ions

    SciTech Connect (OSTI)

    Sung, S. J.; Lee, P. R.; Kim, J. G.; Ryu, M. T.; Park, H. M.; Chung, J. W., E-mail: jwc@postech.ac.kr [Department of Physics, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2014-08-25T23:59:59.000Z

    Despite the noble electronic properties of graphene, its industrial application has been hindered mainly by the absence of a stable means of producing a band gap at the Dirac point (DP). We report a new route to open a band gap (E{sub g}) at DP in a controlled way by depositing positively charged Na{sup +} ions on single layer graphene formed on 6H-SiC(0001) surface. The doping of low energy Na{sup +} ions is found to deplete the ?* band of graphene above the DP, and simultaneously shift the DP downward away from Fermi energy indicating the opening of E{sub g}. The band gap increases with increasing Na{sup +} coverage with a maximum E{sub g}?0.70?eV. Our core-level data, C 1s, Na 2p, and Si 2p, consistently suggest that Na{sup +} ions do not intercalate through graphene, but produce a significant charge asymmetry among the carbon atoms of graphene to cause the opening of a band gap. We thus provide a reliable way of producing and tuning the band gap of graphene by using Na{sup +} ions, which may play a vital role in utilizing graphene in future nano-electronic devices.

  12. One-dimensional electromagnetic band gap structures formed by discharge plasmas in a waveguide

    SciTech Connect (OSTI)

    Arkhipenko, V. I.; Simonchik, L. V., E-mail: l.simonchik@dragon.bas-net.by; Usachonak, M. S. [B.I. Stepanov Institute of Physics of the NAS of Belarus, Ave. Nezavisimostsi 68, 220072 Minsk (Belarus); Callegari, Th.; Sokoloff, J. [Université de Toulouse, UPS, INPT, LAPLACE, Laboratoire Plasma et Conversion d'Energie, 118 route de Narbonne, F-31062 Toulouse cedex 9 (France)

    2014-09-28T23:59:59.000Z

    We demonstrate the ability to develop one-dimensional electromagnetic band gap structure in X-band waveguide solely by using the positive columns of glow discharges in neon at the middle pressure. Plasma inhomogeneities are distributed uniformly along a typical X-band waveguide with cross section of 23?×?10?mm{sup 2}. It is shown that electron densities larger than 10{sup 14?}cm{sup ?3} are needed in order to create an effective one-dimensional electromagnetic band gap structure. Some applications for using the one-dimensional electromagnetic band gap structure in waveguide as a control of microwave (broadband filter and device for variation of pulse duration) are demonstrated.

  13. Polarization dependence of the temporal response of metal-semiconductor-metal photodetectors

    E-Print Network [OSTI]

    Van Driel, Henry M.

    of MSM-PD effi- ciency when the electrode period ( ) is comparable to the wavelength of the incident-semiconductor-metal photodetector temporal response is shown to be significant, and largest for devices with electrode periods less insensitive devices require special electrode patterning7 or . When used as a polarization analyzer/ detector

  14. Direct measurements of band gap grading in polycrystalline CIGS solar cells

    E-Print Network [OSTI]

    Heinrich, M P; Zhang, Y; Kiowski, O; Powalla, M; Lemmer, U; Slobodskyy, A

    2010-01-01T23:59:59.000Z

    We present direct measurements of depth-resolved band gap variations of CuIn(1-x)Ga(x)Se2 thin-film solar cell absorbers. A new measurement technique combining parallel measurements of local thin-film interference and spectral photoluminescence was developed for this purpose. We find sample-dependent correlation parameters between measured band gap depth and composition profiles, and emphasize the importance of direct measurements. These results bring a quantitative insight into the electronic properties of the solar cells and open a new way to analyze parameters that determine the efficiency of solar cells.

  15. Direct measurements of band gap grading in polycrystalline CIGS solar cells

    E-Print Network [OSTI]

    M. P. Heinrich; Z-H. Zhang; Y. Zhang; O. Kiowski; M. Powalla; U. Lemmer; A. Slobodskyy

    2010-09-20T23:59:59.000Z

    We present direct measurements of depth-resolved band gap variations of CuIn(1-x)Ga(x)Se2 thin-film solar cell absorbers. A new measurement technique combining parallel measurements of local thin-film interference and spectral photoluminescence was developed for this purpose. We find sample-dependent correlation parameters between measured band gap depth and composition profiles, and emphasize the importance of direct measurements. These results bring a quantitative insight into the electronic properties of the solar cells and open a new way to analyze parameters that determine the efficiency of solar cells.

  16. New Reconfigurable Power Divider Based on Radial Waveguide and Cylindrical Electromagnetic Band Gap Structure for Low

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Structure for Low Power and Low Cost Smart Antenna Systems Halim Boutayeb, Paul Watson and Toby Kemp AntennaNew Reconfigurable Power Divider Based on Radial Waveguide and Cylindrical Electromagnetic Band Gap halim.boutayeb@huawei.com Abstract--A new low power and low cost technique is proposed for designing

  17. Exploiting pattern transformation to tune phononic band gaps in a two-dimensional granular crystal

    E-Print Network [OSTI]

    ) cylinders is investigated numerically. This system was previously shown to undergo a pattern transformation with uniaxial compression by Go¨ncu¨ et al. [Soft Matter 7, 2321 (2011)]. The dispersion relations, or elastic waves in certain frequency ranges known as band gaps is an important feature of these materials

  18. Band gap structure modification of amorphous anodic Al oxide film by Ti-alloying

    SciTech Connect (OSTI)

    Canulescu, S., E-mail: stec@fotonik.dtu.dk; Schou, J. [Department of Photonics Engineering, Technical University of Denmark, 4000 Roskilde (Denmark); Rechendorff, K.; Pleth Nielsen, L. [Danish Technological Institute, Kongsvang Alle 29, 8000 Aarhus (Denmark); Borca, C. N. [Paul Scherrer Institute, 5232 Villigen (Switzerland); Jones, N. C.; Hoffmann, S. V. [ISA, Department of Physics and Astronomy, Aarhus University, 8000 Aarhus (Denmark); Bordo, K.; Ambat, R. [Department of Mechanical Engineering, Technical University of Denmark, 2800 Kongens Lyngby (Denmark)

    2014-03-24T23:59:59.000Z

    The band structure of pure and Ti-alloyed anodic aluminum oxide has been examined as a function of Ti concentration varying from 2 to 20 at.?%. The band gap energy of Ti-alloyed anodic Al oxide decreases with increasing Ti concentration. X-ray absorption spectroscopy reveals that Ti atoms are not located in a TiO{sub 2} unit in the oxide layer, but rather in a mixed Ti-Al oxide layer. The optical band gap energy of the anodic oxide layers was determined by vacuum ultraviolet spectroscopy in the energy range from 4.1 to 9.2?eV (300–135?nm). The results indicate that amorphous anodic Al{sub 2}O{sub 3} has a direct band gap of 7.3?eV, which is about ?1.4?eV lower than its crystalline counterpart (single-crystal Al{sub 2}O{sub 3}). Upon Ti-alloying, extra bands appear within the band gap of amorphous Al{sub 2}O{sub 3}, mainly caused by Ti 3d orbitals localized at the Ti site.

  19. The Electrical and Band-Gap Properties of Amorphous Zinc-Indium-Tin Oxide Thin Films

    E-Print Network [OSTI]

    Shahriar, Selim

    MRSEC The Electrical and Band-Gap Properties of Amorphous Zinc-Indium-Tin Oxide Thin Films D Science & Engineering Center For zinc-indium-tin oxide (ZITO) films, grown by pulsed-laser deposition was replaced by substitution with zinc and tin in equal molar proportions (co-substitution). All ZITO films

  20. Plasma process-induced band-gap modifications of a strained SiGe heterostructure

    E-Print Network [OSTI]

    Misra, Durgamadhab "Durga"

    Plasma process-induced band-gap modifications of a strained SiGe heterostructure P. K. Swain,a) S the strain of coherently strained SiGe. This work investigates the change in valence-band discontinuity in plasma-exposed SiGe films due to strain relaxation by a capacitance­voltage (C­V) profiling technique

  1. Reflection technique for thermal mapping of semiconductors

    DOE Patents [OSTI]

    Walter, Martin J. (Lee, NY)

    1989-06-20T23:59:59.000Z

    Semiconductors may be optically tested for their temperatures by illuminating them with tunable monochromatic electromagnetic radiation and observing the light reflected off of them. A transition point will occur when the wavelength of the light corresponds with the actual band gap energy of the semiconductor. At the transition point, the image of the semiconductor will appreciably darken as the light is transmitted through it, rather than being reflected off of it. The wavelength of the light at the transition point corresponds to the actual band gap energy and the actual temperature of the semiconductor.

  2. Ultrathin metal-semiconductor-metal resonator for angle invariant visible band transmission filters

    SciTech Connect (OSTI)

    Lee, Kyu-Tae; Seo, Sungyong; Yong Lee, Jae; Jay Guo, L., E-mail: guo@umich.edu [Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2014-06-09T23:59:59.000Z

    We present transmission visible wavelength filters based on strong interference behaviors in an ultrathin semiconductor material between two metal layers. The proposed devices were fabricated on 2?cm?×?2?cm glass substrate, and the transmission characteristics show good agreement with the design. Due to a significantly reduced light propagation phase change associated with the ultrathin semiconductor layer and the compensation in phase shift of light reflecting from the metal surface, the filters show an angle insensitive performance up to ±70°, thus, addressing one of the key challenges facing the previously reported photonic and plasmonic color filters. This principle, described in this paper, can have potential for diverse applications ranging from color display devices to the image sensors.

  3. Semiconductor Quantum Rods as Single Molecule Fluorescent Biological Labels

    E-Print Network [OSTI]

    2006-01-01T23:59:59.000Z

    A. , Gu, W. , Larabell, C. & Alivisatos, A.P. SemiconductorHu, J.T. , Yang, W.D. & Alivisatos, A.P. Band gap variationZanchet, D. , Weiss, S. , ,Alivisatos, A. P. Synthesis and

  4. Mesoscopic pointlike defects in semiconductors: Deep-level energies D. D. Nolte

    E-Print Network [OSTI]

    Nolte, David D.

    -semiconductor heterostructures to include metal-semiconductor,1 insulator-semiconductor, and superconductor-semiconductor

  5. Multiple percolation tunneling staircase in metal-semiconductor nanoparticle composites

    SciTech Connect (OSTI)

    Mukherjee, Rupam; Huang, Zhi-Feng; Nadgorny, Boris [Department of Physics and Astronomy, Wayne State University, Detroit, Michigan 48201 (United States)

    2014-10-27T23:59:59.000Z

    Multiple percolation transitions are observed in a binary system of RuO{sub 2}-CaCu{sub 3}Ti{sub 4}O{sub 12} metal-semiconductor nanoparticle composites near percolation thresholds. Apart from a classical percolation transition, associated with the appearance of a continuous conductance path through RuO{sub 2} metal oxide nanoparticles, at least two additional tunneling percolation transitions are detected in this composite system. Such behavior is consistent with the recently emerged picture of a quantum conductivity staircase, which predicts several percolation tunneling thresholds in a system with a hierarchy of local tunneling conductance, due to various degrees of proximity of adjacent conducting particles distributed in an insulating matrix. Here, we investigate a different type of percolation tunneling staircase, associated with a more complex conductive and insulating particle microstructure of two types of non-spherical constituents. As tunneling is strongly temperature dependent, we use variable temperature measurements to emphasize the hierarchical nature of consecutive tunneling transitions. The critical exponents corresponding to specific tunneling percolation thresholds are found to be nonuniversal and temperature dependent.

  6. Periodic dielectric structure for production of photonic band gap and method for fabricating the same

    DOE Patents [OSTI]

    Ozbay, E.; Tuttle, G.; Michel, E.; Ho, K.M.; Biswas, R.; Chan, C.T.; Soukoulis, C.

    1995-04-11T23:59:59.000Z

    A method is disclosed for fabricating a periodic dielectric structure which exhibits a photonic band gap. Alignment holes are formed in a wafer of dielectric material having a given crystal orientation. A planar layer of elongate rods is then formed in a section of the wafer. The formation of the rods includes the step of selectively removing the dielectric material of the wafer between the rods. The formation of alignment holes and layers of elongate rods and wafers is then repeated to form a plurality of patterned wafers. A stack of patterned wafers is then formed by rotating each successive wafer with respect to the next-previous wafer, and then placing the successive wafer on the stack. This stacking results in a stack of patterned wafers having a four-layer periodicity exhibiting a photonic band gap. 42 figures.

  7. Pre-Stressed Viscoelastic Composites: Effective Incremental Moduli and Band-Gap Tuning

    SciTech Connect (OSTI)

    Parnell, William J. [School of Mathematics, Alan Turing Building, University of Manchester, Manchester, M13 9PL (United Kingdom)

    2010-09-30T23:59:59.000Z

    We study viscoelastic wave propagation along pre-stressed nonlinear elastic composite bars. In the pre-stressed state we derive explicit forms for the effective incremental storage and loss moduli with dependence on the pre-stress. We also derive a dispersion relation for the effective wavenumber in the case of arbitrary frequency, hence permitting a study of viscoelastic band-gap tuning via pre-stress.

  8. Engineering of the band gap and optical properties of thin films of yttrium hydride

    SciTech Connect (OSTI)

    You, Chang Chuan; Mongstad, Trygve; Maehlen, Jan Petter; Karazhanov, Smagul, E-mail: smagulk@ife.no [Institute for Energy Technology, P.O. Box 40, NO-2027 Kjeller (Norway)

    2014-07-21T23:59:59.000Z

    Thin films of oxygen-containing yttrium hydride show photochromic effect at room temperature. In this work, we have studied structural and optical properties of the films deposited at different deposition pressures, discovering the possibility of engineering the optical band gap by variation of the oxygen content. In sum, the transparency of the films and the wavelength range of photons triggering the photochromic effect can be controlled by variation of the deposition pressure.

  9. Band gap tunning in BN-doped graphene systems with high carrier mobility

    SciTech Connect (OSTI)

    Kaloni, T. P.; Schwingenschlögl, U., E-mail: udo.schwingenschlogl@kaust.edu.sa [KAUST, PSE Division, Thuwal 23955-6900 (Saudi Arabia); Joshi, R. P.; Adhikari, N. P. [Central Department of Physics, Tribhuvan University, Kirtipur, Kathmandu (Nepal)

    2014-02-17T23:59:59.000Z

    Using density functional theory, we present a comparative study of the electronic properties of BN-doped graphene monolayer, bilayer, trilayer, and multilayer systems. In addition, we address a superlattice of pristine and BN-doped graphene. Five doping levels between 12.5% and 75% are considered, for which we obtain band gaps from 0.02?eV to 2.43?eV. We demonstrate a low effective mass of the charge carriers.

  10. Self-Assembled Metal/Molecule/Semiconductor Nanostructures for Electronic Device

    E-Print Network [OSTI]

    Woodall, Jerry M.

    565 Self-Assembled Metal/Molecule/Semiconductor Nanostructures for Electronic Device and Contact attracted interest for electronic device and ma- terials applications. The first class involves the for-assembled semiconductor structures, the electronic device functionality has been limited by the difficulty in achieving

  11. Blocking a wave: Frequency band gaps in ice shelves with periodic crevasses

    E-Print Network [OSTI]

    Julian Freed-Brown; Jason M. Amundson; Douglas R. MacAyeal; Wendy W. Zhang

    2011-12-14T23:59:59.000Z

    We assess how the propagation of high-frequency elastic-flexural waves through an ice shelf is modified by the presence of spatially periodic crevasses. Analysis of the normal modes supported by the ice shelf with and without crevasses reveals that a periodic crevasse distribution qualitatively changes the mechanical response. The normal modes of an ice shelf free of crevasses are evenly distributed as a function of frequency. In contrast, the normal modes of a crevasse-ridden ice shelf are distributed unevenly. There are "band gaps", frequency ranges over which no eigenmodes exist. A model ice shelf that is 50 km in lateral extent and 300 m thick with crevasses spaced 500 m apart has a band gap from 0.2 to 0.38 Hz. This is a frequency range relevant for ocean wave/ice-shelf interactions. When the outermost edge of the crevassed ice shelf is oscillated at a frequency within the band gap, the ice shelf responds very differently from a crevasse-free ice shelf. The flexural motion of the crevassed ice shelf is confined to a small region near the outermost edge of the ice shelf and effectively "blocked" from reaching the interior.

  12. Blocking a wave: Frequency band gaps in ice shelves with periodic crevasses

    E-Print Network [OSTI]

    Freed-Brown, Julian; MacAyeal, Douglas R; Zhang, Wendy W

    2011-01-01T23:59:59.000Z

    We assess how the propagation of high-frequency elastic-flexural waves through an ice shelf is modified by the presence of spatially periodic crevasses. Analysis of the normal modes supported by the ice shelf with and without crevasses reveals that a periodic crevasse distribution qualitatively changes the mechanical response. The normal modes of an ice shelf free of crevasses are evenly distributed as a function of frequency. In contrast, the normal modes of a crevasse-ridden ice shelf are distributed unevenly. There are "band gaps", frequency ranges over which no eigenmodes exist. A model ice shelf that is 50 km in lateral extent and 300 m thick with crevasses spaced 500 m apart has a band gap from 0.2 to 0.38 Hz. This is a frequency range relevant for ocean wave/ice-shelf interactions. When the outermost edge of the crevassed ice shelf is oscillated at a frequency within the band gap, the ice shelf responds very differently from a crevasse-free ice shelf. The flexural motion of the crevassed ice shelf is c...

  13. Band gap reduction in GaNSb alloys due to the anion mismatch

    SciTech Connect (OSTI)

    Veal, T.D.; Piper, L.F.J.; Jollands, S.; Bennett, B.R.; Jefferson, P.H.; Thomas, P.A.; McConville, C.F.; Murdin, B.N.; Buckle, L.; Smith, G.W.; Ashley, T. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); School of Electronics and Physical Sciences, University of Surrey, Guildford, GU2 5XH (United Kingdom); QinetiQ Ltd., St. Andrews Road, Malvern, Worcestershire, WR14 3PS (United Kingdom)

    2005-09-26T23:59:59.000Z

    The structural and optoelectronic properties in GaN{sub x}Sb{sub 1-x} alloys (0{<=}x<0.02) grown by molecular-beam epitaxy on both GaSb substrates and AlSb buffer layers on GaAs substrates are investigated. High-resolution x-ray diffraction (XRD) and reciprocal space mapping indicate that the GaN{sub x}Sb{sub 1-x} epilayers are of high crystalline quality and the alloy composition is found to be independent of substrate, for identical growth conditions. The band gap of the GaNSb alloys is found to decrease with increasing nitrogen content from absorption spectroscopy. Strain-induced band-gap shifts, Moss-Burstein effects, and band renormalization were ruled out by XRD and Hall measurements. The band-gap reduction is solely due to the substitution of dilute amounts of highly electronegative nitrogen for antimony, and is greater than observed in GaNAs with the same N content.

  14. active complementary metal-oxide-semiconductor: Topics by E-print...

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

    Metal Oxide Semiconductor (CMOS) tech- Corresponding author. Email address: antonio 465 Tycho Brahe CCD CMOS Physics Websites Summary: 12;12;12;117 Tycho Brahe 20 19 70 CCD...

  15. DESIGN, GROWTH, FABRICATION AND CHARACTERIZATION OF HIGH-BAND GAP InGaN/GaN SOLAR CELLS

    E-Print Network [OSTI]

    Honsberg, Christiana

    DESIGN, GROWTH, FABRICATION AND CHARACTERIZATION OF HIGH-BAND GAP InGaN/GaN SOLAR CELLS Omkar Jani1 with a band gap of 2.4 eV or greater. InxGa1-xN is one of a few alloys that can meet this key requirement. InGaN.4 eV. InGaN has the appropriate optical properties and has been well demonstrated for light

  16. Effect of silver incorporation in phase formation and band gap tuning of tungsten oxide thin films

    SciTech Connect (OSTI)

    Jolly Bose, R.; Kumar, R. Vinod; Sudheer, S. K.; Mahadevan Pillai, V. P. [Department of Optoelectronics, University of Kerala, Kariyavattom, Thiruvananthapuram, Kerala 695581 (India); Reddy, V. R.; Ganesan, V. [UGC - DAE Consortium for Scientific Research, Khandwa Road, Indore 452017, Madhyapradesh (India)

    2012-12-01T23:59:59.000Z

    Silver incorporated tungsten oxide thin films are prepared by RF magnetron sputtering technique. The effect of silver incorporation in micro structure evolution, phase enhancement, band gap tuning and other optical properties are investigated using techniques such as x-ray diffraction, micro-Raman spectroscopy, atomic force microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, and UV-Visible spectroscopy. Effect of silver addition in phase formation and band gap tuning of tungsten oxide thin films are investigated. It is found that the texturing and phase formation improves with enhancement in silver content. It is also found that as the silver incorporation enhances the thickness of the films increases at the same time the strain in the film decreases. Even without annealing the desired phase can be achieved by doping with silver. A broad band centered at the wavelength 437 nm is observed in the absorption spectra of tungsten oxide films of higher silver incorporation and this can be attributed to surface plasmon resonance of silver atoms present in the tungsten oxide matrix. The transmittance of the films is decreased with increase in silver content which can be due to increase in film thickness, enhancement of scattering, and absorption of light caused by the increase of grain size, surface roughness and porosity of films and enhanced absorption due to surface plasmon resonance of silver. It is found that silver can act as the seed for the growth of tungsten oxide grains and found that the grain size increases with silver content which in turn decreases the band gap of tungsten oxide from 3.14 eV to 2.70 eV.

  17. Metal-insulator-semiconductor structures on p-type GaAs with low interface state density

    E-Print Network [OSTI]

    Chen, Zhi

    Metal-insulator-semiconductor structures on p-type GaAs with low interface state density Zhi Chen properties of in situ deposited Si3N4 /Si/p-GaAs metal-insulator-semiconductor structures have been offered by a low gate leakage technology in GaAs, such as metal insulator structures, func- tional Ga

  18. Analysis of plasma-magnetic photonic crystal with a tunable band gap

    SciTech Connect (OSTI)

    Mehdian, H.; Mohammadzahery, Z.; Hasanbeigi, A. [Department of Physics and Plasma Research Institute of Tarbiat Moallem University, 49 Dr Mofatteh Avenue, Tehran 15614 (Iran, Islamic Republic of)

    2013-04-15T23:59:59.000Z

    In this paper, electromagnetic wave propagation through the one-dimensional plasma-magnetic photonic crystal in the presence of external magnetic field has been analyzed. The dispersion relation, transmission and reflection coefficients have been obtained by using the transfer matrix method. It is investigated how photonic band gap of photonic crystals will be tuned when both dielectric function {epsilon} and magnetic permeability {mu} of the constitutive materials, depend on applied magnetic field. This is shown by one dimensional photonic crystals consisting of plasma and ferrite material layers stacked alternately.

  19. Coherent ExcitonSurface-Plasmon-Polariton Interaction in Hybrid Metal-Semiconductor Nanostructures

    E-Print Network [OSTI]

    Oldenburg, Carl von Ossietzky Universität

    Coherent Exciton­Surface-Plasmon-Polariton Interaction in Hybrid Metal-Semiconductor Nanostructures 2008; published 8 September 2008) We report measurements of a coherent coupling between surface plasmon when placed close to a metallic nanostructure due to its coupling to surface plasmon polaritons (SPPs

  20. Periodic dielectric structure for production of photonic band gap and devices incorporating the same

    DOE Patents [OSTI]

    Ho, Kai-Ming (Ames, IA); Chan, Che-Ting (Ames, IA); Soukoulis, Costas (Ames, IA)

    1994-08-02T23:59:59.000Z

    A periodic dielectric structure which is capable of producing a photonic band gap and which is capable of practical construction. The periodic structure is formed of a plurality of layers, each layer being formed of a plurality of rods separated by a given spacing. The material of the rods contrasts with the material between the rods to have a refractive index contrast of at least two. The rods in each layer are arranged with their axes parallel and at a given spacing. Adjacent layers are rotated by 90.degree., such that the axes of the rods in any given layer are perpendicular to the axes in its neighbor. Alternating layers (that is, successive layers of rods having their axes parallel such as the first and third layers) are offset such that the rods of one are about at the midpoint between the rods of the other. A four-layer periocity is thus produced, and successive layers are stacked to form a three-dimensional structure which exhibits a photonic band gap. By virtue of forming the device in layers of elongate members, it is found that the device is susceptible of practical construction.

  1. Ultraviolet GaN photodetectors on Si via oxide buffer heterostructures with integrated short period oxide-based distributed Bragg reflectors and leakage suppressing metal-oxide-semiconductor contacts

    SciTech Connect (OSTI)

    Szyszka, A., E-mail: szyszka@ihp-microelectronics.com, E-mail: adam.szyszka@pwr.wroc.pl [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Faculty of Microsystem Electronics and Photonics, Wroclaw University of Technology, Janiszewskiego 11/17, 50-372 Wroclaw (Poland); Lupina, L.; Lupina, G.; Schubert, M. A.; Zaumseil, P. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Haeberlen, M.; Storck, P.; Thapa, S. B. [Siltronic, Hanns-Seidel-Platz 4, 81737 München (Germany); Schroeder, T. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); BTU Cottbus-Senftenberg, Konrad-Zuse-Strasse 1, 03046 Cottbus (Germany)

    2014-08-28T23:59:59.000Z

    Based on a novel double step oxide buffer heterostructure approach for GaN integration on Si, we present an optimized Metal-Semiconductor-Metal (MSM)-based Ultraviolet (UV) GaN photodetector system with integrated short-period (oxide/Si) Distributed Bragg Reflector (DBR) and leakage suppressing Metal-Oxide-Semiconductor (MOS) electrode contacts. In terms of structural properties, it is demonstrated by in-situ reflection high energy electron diffraction and transmission electron microscopy-energy dispersive x-ray studies that the DBR heterostructure layers grow with high thickness homogeneity and sharp interface structures sufficient for UV applications; only minor Si diffusion into the Y{sub 2}O{sub 3} films is detected under the applied thermal growth budget. As revealed by comparative high resolution x-ray diffraction studies on GaN/oxide buffer/Si systems with and without DBR systems, the final GaN layer structure quality is not significantly influenced by the growth of the integrated DBR heterostructure. In terms of optoelectronic properties, it is demonstrated that—with respect to the basic GaN/oxide/Si system without DBR—the insertion of (a) the DBR heterostructures and (b) dark current suppressing MOS contacts enhances the photoresponsivity below the GaN band-gap related UV cut-off energy by almost up to two orders of magnitude. Given the in-situ oxide passivation capability of grown GaN surfaces and the one order of magnitude lower number of superlattice layers in case of higher refractive index contrast (oxide/Si) systems with respect to classical III-N DBR superlattices, virtual GaN substrates on Si via functional oxide buffer systems are thus a promising robust approach for future GaN-based UV detector technologies.

  2. Fluorine Substituted Conjugated Polymer of Medium Band Gap Yields 7% Efficiency in Polymer--Fullerene Solar Cells

    SciTech Connect (OSTI)

    Price, S C; Stuart, Andrew C.; Yang, L; Zhou, H; You, Wei

    2011-01-01T23:59:59.000Z

    Recent research advances on conjugated polymers for photovoltaic devices have focused on creating low band gap materials, but a suitable band gap is only one of many performance criteria required for a successful conjugated polymer. This work focuses on the design of two medium band gap (?2.0 eV) copolymers for use in photovoltaic cells which are designed to possess a high hole mobility and low highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels. The resulting fluorinated polymer PBnDT?FTAZ exhibits efficiencies above 7% when blended with [6,6]-phenyl C{sub 61}-butyric acid methyl ester in a typical bulk heterojunction, and efficiencies above 6% are still maintained at an active layer thicknesses of 1 ?m. PBnDT?FTAZ outperforms poly(3-hexylthiophene), the current medium band gap polymer of choice, and thus is a viable candidate for use in highly efficient tandem cells. PBnDT?FTAZ also highlights other performance criteria which contribute to high photovoltaic efficiency, besides a low band gap.

  3. Electrical characterization of native-oxide InAlPGaAs metal-oxide-semiconductor heterostructures using

    E-Print Network [OSTI]

    Electrical characterization of native-oxide InAlPÕGaAs metal-oxide-semiconductor heterostructures 8 December 2003; accepted 20 January 2004 InAIP native oxide/GaAs metal-oxide-semiconductor MOS of Schottky gates can lead to excessive gate leakage current and also restrict the forward gate bias to only

  4. AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors using barium strontium titanate

    E-Print Network [OSTI]

    York, Robert A.

    AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors using barium strontium; published 13 October 2004) Use of high-k gate dielectrics in AlGaN/GaN heterostructure field transconductance and pinchoff voltage. To achieve this, AlGaN/GaN metal-oxide-semiconductor heterostructure field

  5. Microwave band gap and cavity mode in spoof-insulator-spoof waveguide with multiscale structured surface

    E-Print Network [OSTI]

    Zhang, Qiang; Han, Dezhuan; Qin, Fei Fei; Zhang, Xiao Ming; Yao, Yong

    2015-01-01T23:59:59.000Z

    We propose a multiscale spoof-insulator-spoof (SIS) waveguide by introducing periodic geometry modulation in the wavelength scale to a SIS waveguide made of perfect electric conductor. The MSIS consists of multiple SIS subcells. The dispersion relationship of the fundamental guided mode of the spoof surface plasmon polaritons (SSPPs) is studied analytically within the small gap approximation. It is shown that the multiscale SIS possesses microwave band gap (MBG) due to the Bragg scattering. The "gap maps" in the design parameter space are provided. We demonstrate that the geometry of the subcells can efficiently adjust the effective refraction index of the elementary SIS and therefore further control the width and the position of the MBG. The results are in good agreement with numerical calculations by the finite element method (FEM). For finite-sized MSIS of given geometry in the millimeter scale, FEM calculations show that the first-order symmetric SSPP mode has zero transmission in the MBG within frequency...

  6. Band gap corrections for molecules and solids using Koopmans theorem and Wannier functions

    E-Print Network [OSTI]

    Ma, Jie

    2015-01-01T23:59:59.000Z

    We have proposed a method for correcting the Kohn-Sham eigen energies in the density functional theory (DFT) based on the Koopmans theorem using Wannier functions. The method provides a general approach applicable for molecules and solids for electronic structure calculations. It does not have any adjustable parameters and the computational cost is at the DFT level. For solids, the calculated eigen energies agree well with the experiments for not only the band gaps, but also the energies of other valence and conduction bands. For molecules, the calculated eigen energies agree well with the experimental ionization potentials and electron affinities, and show better trends than the traditional Delta-self-consistent-field (?SCF) results.

  7. L{sub g}?=?100?nm In{sub 0.7}Ga{sub 0.3}As quantum well metal-oxide semiconductor field-effect transistors with atomic layer deposited beryllium oxide as interfacial layer

    SciTech Connect (OSTI)

    Koh, D., E-mail: dh.koh@utexas.edu, E-mail: Taewoo.Kim@sematech.org [Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758 (United States); SEMATECH, Inc., Albany, New York 12203 (United States); Kwon, H. M. [Department of Electronics Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Kim, T.-W., E-mail: dh.koh@utexas.edu, E-mail: Taewoo.Kim@sematech.org; Veksler, D.; Gilmer, D.; Kirsch, P. D. [SEMATECH, Inc., Albany, New York 12203 (United States); Kim, D.-H. [SEMATECH, Inc., Albany, New York 12203 (United States); GLOBALFOUNDRIES, Malta, New York 12020 (United States); Hudnall, Todd W. [Department of Chemistry and Biochemistry, Texas State University, San Marcos, Texas, 78666 (United States); Bielawski, Christopher W. [Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712 (United States); Maszara, W. [GLOBALFOUNDRIES, Santa Clara, California 95054 (United States); Banerjee, S. K. [Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758 (United States)

    2014-04-21T23:59:59.000Z

    In this study, we have fabricated nanometer-scale channel length quantum-well (QW) metal-oxide-semiconductor field effect transistors (MOSFETs) incorporating beryllium oxide (BeO) as an interfacial layer. BeO has high thermal stability, excellent electrical insulating characteristics, and a large band-gap, which make it an attractive candidate for use as a gate dielectric in making MOSFETs. BeO can also act as a good diffusion barrier to oxygen owing to its small atomic bonding length. In this work, we have fabricated In{sub 0.53}Ga{sub 0.47}As MOS capacitors with BeO and Al{sub 2}O{sub 3} and compared their electrical characteristics. As interface passivation layer, BeO/HfO{sub 2} bilayer gate stack presented effective oxide thickness less 1 nm. Furthermore, we have demonstrated In{sub 0.7}Ga{sub 0.3}As QW MOSFETs with a BeO/HfO{sub 2} dielectric, showing a sub-threshold slope of 100?mV/dec, and a transconductance (g{sub m,max}) of 1.1 mS/?m, while displaying low values of gate leakage current. These results highlight the potential of atomic layer deposited BeO for use as a gate dielectric or interface passivation layer for III–V MOSFETs at the 7?nm technology node and/or beyond.

  8. Low resistance barrier layer for isolating, adhering, and passivating copper metal in semiconductor fabrication

    DOE Patents [OSTI]

    Weihs, Timothy P. (Baltimore, MD); Barbee, Jr., Troy W. (Palto Alto, CA)

    2002-01-01T23:59:59.000Z

    Cubic or metastable cubic refractory metal carbides act as barrier layers to isolate, adhere, and passivate copper in semiconductor fabrication. One or more barrier layers of the metal carbide are deposited in conjunction with copper metallizations to form a multilayer characterized by a cubic crystal structure with a strong (100) texture. Suitable barrier layer materials include refractory transition metal carbides such as vanadium carbide (VC), niobium carbide (NbC), tantalum carbide (TaC), chromium carbide (Cr.sub.3 C.sub.2), tungsten carbide (WC), and molybdenum carbide (MoC).

  9. HIGH-K-INAS METAL-OXIDE-SEMICONDUCTOR CAPACITORS FORMED BY ATOMIC-LAYER DEPOSITION

    E-Print Network [OSTI]

    -k-InAs metal-oxide-semiconductor capacitors. Devices are formed using various substrate pretreatments, film by the Terman method to be in the 1013 cm-2 -eV-1 range at midgap. TEM and XPS data suggest the high trap

  10. Photovoltaic devices with low band gap polymers Eva Bundgaarda, Sean Shaheenb, David S. Ginleyb, Frederik C. Krebsa

    E-Print Network [OSTI]

    Photovoltaic devices with low band gap polymers Eva Bundgaarda, Sean Shaheenb, David S. Ginleyb, Colorado, USA Abstract Progress in organic photovoltaic devices has recently resulted in reported temperature, active area of the device and molecular weight of the polymer, on the photovoltaic response

  11. Multipole-cancellation mechanism for high-Q cavities in the absence of a complete photonic band gap

    E-Print Network [OSTI]

    Multipole-cancellation mechanism for high-Q cavities in the absence of a complete photonic band gap in the lowest-order term s of the multipole far-field radiation expansion. We focus on the system of photonic-order term s in a multipole expansion of the far-field radiation, distinct from the near- field multipole

  12. Molecular beam epitaxy of n-type ZnS: A wide band gap emitter for heterojunction PV devices

    E-Print Network [OSTI]

    Atwater, Harry

    Molecular beam epitaxy of n-type ZnS: A wide band gap emitter for heterojunction PV devices Jeffrey and AZO transparent conductive oxides did not. Applications to novel PV devices incorporating low electron-ray diffraction, zinc compounds. I. INTRODUCTION The growing interest in scalable, thin-film photovoltaics (PV

  13. 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 to show that (1) there can be a beneficial effect of grading, (2) in standard thick- ness CIGS cells

  14. Elastic and viscoelastic effects in rubber/air acoustic band gap structures: A theoretical and experimental study

    E-Print Network [OSTI]

    Deymier, Pierre

    Elastic and viscoelastic effects in rubber/air acoustic band gap structures: A theoretical rubber/air phononic crystal structures is investigated theoretically and experimentally. We introduce in a solid rubber matrix, as well as an array of rubber cylinders in an air matrix, are shown to behave

  15. Optical bistability and phase transitions in a doped photonic band-gap material Sajeev John and Tran Quang

    E-Print Network [OSTI]

    John, Sajeev

    in a pseudophotonic band gap PBG to an applied laser field. It is shown that in the case when the variance of resonant reactive ion etching techniques. The relative dif- ficulty in drilling to a depth of more than a few unit

  16. Effects of surface termination on the band gap of ultrabright Si29 nanoparticles: Experiments and computational models

    E-Print Network [OSTI]

    Braun, Paul

    Effects of surface termination on the band gap of ultrabright Si29 nanoparticles: Experiments constituting a H-terminated reconstructed Si surface was recently proposed as a structural prototype termination with a N linkage in butylamine and O linkage in pentane . The emission band for N-termination

  17. Here, we present the fabrication and use of plastic Photonic Band Gap Bragg fibres in photonic textiles for applications in

    E-Print Network [OSTI]

    Skorobogatiy, Maksim

    Here, we present the fabrication and use of plastic Photonic Band Gap Bragg fibres in photonic­section, Bragg fibres feature periodic sequence of layers of two distinct plastics. Under ambient illumination SCHICKER2 , NING GUO1 , CHARLES DUBOIS3 , RACHEL WINGFIELD2 & MAKSIM SKOROBOGATIY1 COLOUR-ON-DEMAND

  18. Band gap tuning in GaN through equibiaxial in-plane strains S. K. Yadav,2

    E-Print Network [OSTI]

    Alpay, S. Pamir

    in photovoltaics and light emission diodes LEDs . The InGaN system has been intensively studied during the past to the large atomic size mismatch between Ga and In.3 Thus, other methods to tune the band gap are needed for potential appli- cations of GaN and related materials systems. It is well-known that the structure

  19. Using a Semiconductor-to-Metal Transition to Control Optical Transmission through Subwavelength Hole Arrays

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

    Donev, E. U.; Suh, J. Y.; Lopez, R.; Feldman, L. C.; Haglund, R. F.

    2008-01-01T23:59:59.000Z

    We describe a simple configuration in which the extraordinary optical transmission effect through subwavelength hole arrays in noble-metal films can be switched by the semiconductor-to-metal transition in an underlying thin film of vanadium dioxide. In these experiments, the transition is brought about by thermal heating of the bilayer film. The surprising reverse hysteretic behavior of the transmission through the subwavelength holes in the vanadium oxide suggest that this modulation is accomplished by a dielectric-matching condition rather than plasmon coupling through the bilayer film. The results of this switching, including the wavelength dependence, are qualitatively reproduced by a transfer matrix model.more »The prospects for effecting a similar modulation on a much faster time scale by using ultrafast laser pulses to trigger the semiconductor-to-metal transition are also discussed.« less

  20. Impact of GaN cap on charges in Al?O?/(GaN/)AlGaN/GaN metal-oxide-semiconductor heterostructures analyzed by means of capacitance measurements and simulations

    SciTech Connect (OSTI)

    ?apajna, M., E-mail: milan.tapajna@savba.sk; Jurkovi?, M.; Válik, L.; Haš?ík, Š.; Gregušová, D.; Kuzmík, J. [Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Brunner, F.; Cho, E.-M. [Ferdinand-Braun-Institut, Leibniz Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Strasse 4, 12489 Berlin (Germany); Hashizume, T. [Research Center for Integrated Quantum Electronics (RCIQE), Hokkaido University, 060-0814 Sapporo, Japan and JST-CREST, 102-0075 Tokyo (Japan)

    2014-09-14T23:59:59.000Z

    Oxide/semiconductor interface trap density (D{sub it}) and net charge of Al?O?/(GaN)/AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistor (MOS-HEMT) structures with and without GaN cap were comparatively analyzed using comprehensive capacitance measurements and simulations. D{sub it} distribution was determined in full band gap of the barrier using combination of three complementary capacitance techniques. A remarkably higher D{sub it} (?5–8?×?10¹²eV?¹?cm?²) was found at trap energies ranging from EC-0.5 to 1?eV for structure with GaN cap compared to that (D{sub it}???2–3?×?10¹²eV?¹?cm?²) where the GaN cap was selectively etched away. D{sub it} distributions were then used for simulation of capacitance-voltage characteristics. A good agreement between experimental and simulated capacitance-voltage characteristics affected by interface traps suggests (i) that very high D{sub it} (>10¹³eV?¹?cm?²) close to the barrier conduction band edge hampers accumulation of free electron in the barrier layer and (ii) the higher D{sub it} centered about EC-0.6?eV can solely account for the increased C-V hysteresis observed for MOS-HEMT structure with GaN cap. Analysis of the threshold voltage dependence on Al?O? thickness for both MOS-HEMT structures suggests that (i) positive charge, which compensates the surface polarization, is not necessarily formed during the growth of III-N heterostructure, and (ii) its density is similar to the total surface polarization charge of the GaN/AlGaN barrier, rather than surface polarization of the top GaN layer only. Some constraints for the positive surface compensating charge are discussed.

  1. Photonic band gap airbridge microcavity resonances in GaAs/AlxOy waveguides

    E-Print Network [OSTI]

    Fan, Shanhui

    -dielectric-contrast GaAs/AlxOy III­V compound semiconductor structure. The photonic crystal is defined by a regularly of optical states will be modified and quantized by such a cavity. Typical semiconductor optical cavities measurements of a one- dimensional PBG air-bridge optical microcavity are pre- sented here. A schematic

  2. Method for implantation of high dopant concentrations in wide band gap materials

    DOE Patents [OSTI]

    Usov, Igor (Los Alamos, NM); Arendt, Paul N. (Los Alamos, NM)

    2009-09-15T23:59:59.000Z

    A method that combines alternate low/medium ion dose implantation with rapid thermal annealing at relatively low temperatures. At least one dopant is implanted in one of a single crystal and an epitaxial film of the wide band gap compound by a plurality of implantation cycles. The number of implantation cycles is sufficient to implant a predetermined concentration of the dopant in one of the single crystal and the epitaxial film. Each of the implantation cycles includes the steps of: implanting a portion of the predetermined concentration of the one dopant in one of the single crystal and the epitaxial film; annealing one of the single crystal and the epitaxial film and implanted portion at a predetermined temperature for a predetermined time to repair damage to one of the single crystal and the epitaxial film caused by implantation and activates the implanted dopant; and cooling the annealed single crystal and implanted portion to a temperature of less than about 100.degree. C. This combination produces high concentrations of dopants, while minimizing the defect concentration.

  3. Gallium arsenide-based ternary compounds and multi-band-gap solar cell research

    SciTech Connect (OSTI)

    Vernon, S. (Spire Corp., Bedford, MA (United States))

    1993-02-01T23:59:59.000Z

    Aim of this contract is the achievement of a high-efficiency, low-cost solar cell. The basic approach to the problem is centered upon the heteroepitaxial growth of a III-V compound material onto a single-crystal silicon wafer. The growth technique employed is metalorganic chemical vapor deposition. The silicon wafer may serve as a mechanical substrate and ohmic contact for a single-junction device, or may contain a p-n junction of its own and form the bottom cell of a two junction tandem solar cell structure. The III-V material for the single-junction case is GaAs and for the two-junction case is either GaAlAs or GaAsP, either material having the proper composition to yield a band gap of approximately 1.7 eV. Results achieved in this contract include the following: (1) a 17.6% efficient GaAs-on-Si solar cell; (2) an 18.5% efficient GaAs-on-Si concentrator solar cell at 400 suns; (3) a 24.8% efficient GaAs-on-GaAs solar cell; (4) a 28.7% efficient GaAs-on-GaAs concentrator solar cell at 200 suns; (5) measurement of the effects of dislocation density and emitter doping on GaAs cells; and (6) improvements in the growth process to achieve reproducible thin AlGaAs window layers with low recombination velocities and environmental stability.

  4. Effect of Temperature on GaGdO/GaN Metal Oxide Semiconductor Field Effect Transistors

    SciTech Connect (OSTI)

    Abernathy, C.R.; Baca, A.; Chu, S.N.G.; Hong, M.; Lothian, J.R.; Marcus, M.A.; Pearton, S.J.; Ren, F.; Schurman, M.J.

    1998-10-14T23:59:59.000Z

    GaGdO was deposited on GaN for use as a gate dielectric in order to fabricate a depletion metal oxide semiconductor field effect transistor (MOSFET). This is the fmt demonstration of such a device in the III-Nitride system. Analysis of the effect of temperature on the device shows that gate leakage is significantly reduced at elevated temperature relative to a conventional metal semiconductor field effeet transistor (MESFET) fabricated on the same GaN layer. MOSFET device operation in fact improved upon heating to 400 C. Modeling of the effeet of temperature on contact resistance suggests that the improvement is due to a reduction in the parasitic resistances present in the device.

  5. X-Band Photonic Band-Gap Accelerator Structure Breakdown Experiment

    SciTech Connect (OSTI)

    Marsh, Roark A.; /MIT /MIT /NIFS, Gifu /JAERI, Kyoto /LLNL, Livermore; Shapiro, Michael A.; Temkin, Richard J.; /MIT; Dolgashev, Valery A.; Laurent, Lisa L.; Lewandowski, James R.; Yeremian, A.Dian; Tantawi, Sami G.; /SLAC

    2012-06-11T23:59:59.000Z

    In order to understand the performance of photonic band-gap (PBG) structures under realistic high gradient, high power, high repetition rate operation, a PBG accelerator structure was designed and tested at X band (11.424 GHz). The structure consisted of a single test cell with matching cells before and after the structure. The design followed principles previously established in testing a series of conventional pillbox structures. The PBG structure was tested at an accelerating gradient of 65 MV/m yielding a breakdown rate of two breakdowns per hour at 60 Hz. An accelerating gradient above 110 MV/m was demonstrated at a higher breakdown rate. Significant pulsed heating occurred on the surface of the inner rods of the PBG structure, with a temperature rise of 85 K estimated when operating in 100 ns pulses at a gradient of 100 MV/m and a surface magnetic field of 890 kA/m. A temperature rise of up to 250 K was estimated for some shots. The iris surfaces, the location of peak electric field, surprisingly had no damage, but the inner rods, the location of the peak magnetic fields and a large temperature rise, had significant damage. Breakdown in accelerator structures is generally understood in terms of electric field effects. These PBG structure results highlight the unexpected role of magnetic fields in breakdown. The hypothesis is presented that the moderate level electric field on the inner rods, about 14 MV/m, is enhanced at small tips and projections caused by pulsed heating, leading to breakdown. Future PBG structures should be built to minimize pulsed surface heating and temperature rise.

  6. Thermovoltaic semiconductor device including a plasma filter

    DOE Patents [OSTI]

    Baldasaro, Paul F. (Clifton Park, NY)

    1999-01-01T23:59:59.000Z

    A thermovoltaic energy conversion device and related method for converting thermal energy into an electrical potential. An interference filter is provided on a semiconductor thermovoltaic cell to pre-filter black body radiation. The semiconductor thermovoltaic cell includes a P/N junction supported on a substrate which converts incident thermal energy below the semiconductor junction band gap into electrical potential. The semiconductor substrate is doped to provide a plasma filter which reflects back energy having a wavelength which is above the band gap and which is ineffectively filtered by the interference filter, through the P/N junction to the source of radiation thereby avoiding parasitic absorption of the unusable portion of the thermal radiation energy.

  7. Engineering direct-indirect band gap transition in wurtzite GaAs nanowires through size and uniaxial strain

    E-Print Network [OSTI]

    Copple, Andrew; Peng, Xihong; 10.1063/1.4718026

    2012-01-01T23:59:59.000Z

    Electronic structures of wurtzite GaAs nanowires in the [0001] direction were studied using first-principles calculations. It was found that the band gap of GaAs nanowires experience a direct-to-indirect transition when the diameter of the nanowires is smaller than ~28 {\\AA}. For those thin GaAs nanowires with an indirect band gap, it was found that the gap can be tuned to be direct if a moderate external uniaxial strain is applied. Both tensile and compressive strain can trigger the indirect-to-direct gap transition. The critical strains for the gap-transition are determined by the energy crossover of two states in conduction bands.

  8. Wide-band-gap InAlAs solar cell for an alternative multijunction approach Marina S. Leite,1,a

    E-Print Network [OSTI]

    Atwater, Harry

    Wide-band-gap InAlAs solar cell for an alternative multijunction approach Marina S. Leite,1,a Robyn; published online 28 February 2011 We have fabricated an In0.52Al0.48As solar cell lattice-matched to In-free InxAl1-xAs alloyed layers were used to fabricate the single junction solar cell. Photoluminescence

  9. Superatoms and Metal-Semiconductor Motifs for Cluster Materials

    SciTech Connect (OSTI)

    Castleman, A. W.

    2013-10-11T23:59:59.000Z

    A molecular understanding of catalysis and catalytically active materials is of fundamental importance in designing new substances for applications in energy and fuels. We have performed reactivity studies and ultrafast ionization and coulomb explosion studies on a variety of catalytically-relevant materials, including transition metal oxides of Fe, Co, Ni, Cu, Ti, V, Nb, and Ta. We demonstrate that differences in charge state, geometry, and elemental composition of clusters of such materials determine chemical reactivity and ionization behavior, crucial steps in improving performance of catalysts.

  10. Optical limiting of layered transition metal dichalcogenide semiconductors

    E-Print Network [OSTI]

    Dong, Ningning; Feng, Yanyan; Zhang, Saifeng; Zhang, Xiaoyan; Chang, Chunxia; Fan, Jintai; Zhang, Long; Wang, Jun

    2015-01-01T23:59:59.000Z

    Nonlinear optical property of transition metal dichalcogenide (TMDC) nanosheet dispersions, including MoS2, MoSe2, WS2, and WSe2, was performed by using Z-scan technique with ns pulsed laser at 1064 nm and 532 nm. The results demonstrate that the TMDC dispersions exhibit significant optical limiting response at 1064 nm due to nonlinear scattering, in contrast to the combined effect of both saturable absorption and nonlinear scattering at 532 nm. Selenium compounds show better optical limiting performance than that of the sulfides in the near infrared. A liquid dispersion system based theoretical modelling is proposed to estimate the number density of the nanosheet dispersions, the relationship between incident laser fluence and the size of the laser generated micro-bubbles, and hence the Mie scattering-induced broadband optical limiting behavior in the TMDC dispersions.

  11. 1/f noise in semiconductor and metal nanocrystal solids

    SciTech Connect (OSTI)

    Liu, Heng, E-mail: leophy@gmail.com; Lhuillier, Emmanuel, E-mail: emmanuel.lhuillier@espci.fr; Guyot-Sionnest, Philippe [James Franck Institute, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637 (United States)

    2014-04-21T23:59:59.000Z

    Electrical 1/f noise is measured in thin films of CdSe, CdSe/CdS, ZnO, HgTe quantum dots and Au nanocrystals. The 1/f noise, normalized per nanoparticle, shows no systematic dependence on the nanoparticle material and the coupling material. However, over 10 orders of magnitude, it correlates well with the nearest neighbor conductance suggesting some universal magnitude of the 1/f noise in these granular conductors. In the hopping regime, the main mechanism of 1/f noise is determined to be mobility fluctuated. In the metallic regime obtained with gold nanoparticle films, the noise drops to a similar level as bulk gold films and with a similar temperature dependence.

  12. Antiferromagnetic half-metals, gapless half-metals, and spin gapless semiconductors: The D0{sub 3}-type Heusler alloys

    SciTech Connect (OSTI)

    Gao, G. Y., E-mail: guoying-gao@mail.hust.edu.cn; Yao, Kai-Lun, E-mail: klyao@mail.hust.edu.cn [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China)] [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2013-12-02T23:59:59.000Z

    High-spin-polarization materials are desired for the realization of high-performance spintronic devices. We combine recent experimental and theoretical findings to theoretically design several high-spin-polarization materials in binary D0{sub 3}-type Heusler alloys: gapless (zero-gap) half-metallic ferrimagnets of V{sub 3}Si and V{sub 3}Ge, half-metallic antiferromagnets of Mn{sub 3}Al and Mn{sub 3}Ga, half-metallic ferrimagnets of Mn{sub 3}Si and Mn{sub 3}Ge, and a spin gapless semiconductor of Cr{sub 3}Al. The high spin polarization, zero net magnetic moment, zero energy gap, and slight disorder compared to the ternary and quaternary Heusler alloys make these binary materials promising candidates for spintronic applications. All results are obtained by the electronic structure calculations from first-principles.

  13. Antiferromagnetic exchange bias of a ferromagnetic semiconductor by a ferromagnetic metal

    E-Print Network [OSTI]

    Olejnik, K.

    2010-01-01T23:59:59.000Z

    exchange bias of a magnetic semiconductor by a magneticexchange bias in the magnetic semiconductor. The shape and

  14. Disordered electronic and magnetic systems - transition metal (Mn) and rare earth (Gd) doped amorphous group IV semiconductors (C, Si, Ge)

    E-Print Network [OSTI]

    Zeng, Li

    2007-01-01T23:59:59.000Z

    1.1 Magnetic Semiconductors . . . . . . . . . . . . . . .Semiconductors . . . . . . . . . . . . . . . . . . . 1.3in Semiconductors . . . . . . . . . . . . . . . . . . 1.3.5

  15. Amorphous silicon enhanced metal-insulator-semiconductor contacts for silicon solar cells

    SciTech Connect (OSTI)

    Bullock, J., E-mail: james.bullock@anu.edu.au; Cuevas, A.; Yan, D. [Research School of Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Demaurex, B.; Hessler-Wyser, A.; De Wolf, S. [Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Micro Engineering (IMT), Photovoltaics and Thin Film Electronic Laboratory PVLab, Maladière 71b, CH-200 Neuchâtel (Switzerland)

    2014-10-28T23:59:59.000Z

    Carrier recombination at the metal-semiconductor contacts has become a significant obstacle to the further advancement of high-efficiency diffused-junction silicon solar cells. This paper provides the proof-of-concept of a procedure to reduce contact recombination by means of enhanced metal-insulator-semiconductor (MIS) structures. Lightly diffused n{sup +} and p{sup +} surfaces are passivated with SiO{sub 2}/a-Si:H and Al{sub 2}O{sub 3}/a-Si:H stacks, respectively, before the MIS contacts are formed by a thermally activated alloying process between the a-Si:H layer and an overlying aluminum film. Transmission/scanning transmission electron microscopy (TEM/STEM) and energy dispersive x-ray spectroscopy are used to ascertain the nature of the alloy. Idealized solar cell simulations reveal that MIS(n{sup +}) contacts, with SiO{sub 2} thicknesses of ?1.55?nm, achieve the best carrier-selectivity producing a contact resistivity ?{sub c} of ?3 m? cm{sup 2} and a recombination current density J{sub 0c} of ?40 fA/cm{sup 2}. These characteristics are shown to be stable at temperatures up to 350?°C. The MIS(p{sup +}) contacts fail to achieve equivalent results both in terms of thermal stability and contact characteristics but may still offer advantages over directly metallized contacts in terms of manufacturing simplicity.

  16. Band Gap Shift of GaN under Uniaxial Strain Compression H. Y. Peng, M. D. McCluskey, Y. M. Gupta, M. Kneissl1

    E-Print Network [OSTI]

    McCluskey, Matthew

    Band Gap Shift of GaN under Uniaxial Strain Compression H. Y. Peng, M. D. McCluskey, Y. M. Gupta, M.S.A. ABSTRACT The band-gap shift of GaN:Mg epilayers on (0001)-oriented sapphire was studied as a function is approximately 0.026 eV/GPa. Combining this result with the known behavior of wurtzite GaN under hydrostatic

  17. Shock-induced band-gap shift in GaN: Anisotropy of the deformation potentials H. Y. Peng, M. D. McCluskey,* and Y. M. Gupta

    E-Print Network [OSTI]

    McCluskey, Matthew

    Shock-induced band-gap shift in GaN: Anisotropy of the deformation potentials H. Y. Peng, M. D. Mc Alto, California 94304, USA Received 19 October 2004; published 24 March 2005 The band-gap shift of GaN=1.9 eV, and D4=-1.0 eV. These values indicate that the deformation potentials in wurtzite GaN

  18. Production of pulsed, mass-selected beams of metal and semiconductor clusters

    SciTech Connect (OSTI)

    Kamalou, Omar; Rangama, Jimmy; Ramillon, Jean-Marc; Guinement, Patrick; Huber, Bernd A. [CIMAP, CEA-CNRS-ENSICaen-UCBN, Bv. Henry Becquerel (B.P. 5133), F-14070 Caen Cedex 05 (France)

    2008-06-15T23:59:59.000Z

    We report on the development of a beam line for mass-selected metal and semiconductor clusters. The cluster source combines the principles of plasma sputtering and gas condensation. Both techniques together allow to produce clusters in a wide size range. With the aid of a time-of-flight system, small clusters (i.e., Cu{sub n}{sup +}, n<100) are selected and pure beams containing only one cluster size are provided. For large clusters (containing several thousands of atoms), a beam with a narrow size distribution is obtained. A 90 deg. quadrupole deviator is used to separate charged clusters from neutral ones.

  19. Structure and magnetism of transition-metal implanted dilute magnetic semiconductors

    E-Print Network [OSTI]

    Pereira, Lino; Temst, K; Araújo, JP; Wahl, U

    The discovery of a dilute magnetic semiconductor (DMS) in which ferromagnetism is carrier-mediated and persists above room temperature is a critical step towards the development of semiconductor-based spintronics. Among the many types of DMS materials which have been investigated, the current research interest can be narrowed down to two main classes of materials: (1) narrow-gap III-V semiconductors, mostly GaAs and InAs, doped with Mn; (2) wide-gap oxides and nitrides doped with 3d transition metals, mostly Mn- and Co-doped ZnO and Mn-doped GaN. With a number of interesting functionalities deriving from the carrier-mediated ferromagnetism and demonstrated in various proof-of-concept devices, Mn-doped GaAs has become, among DMS materials, one of the best candidates for technological application. However, despite major developments over the last 15 years, the maximum Curie temperature (185 K) remains well below room temperature. On the other hand, wide-gap DMS materials appear to exhibit ferromagnetic behavior...

  20. A 10-kW SiC Inverter with A Novel Printed Metal Power Module With Integrated Cooling Using Additive Manufacturing

    SciTech Connect (OSTI)

    Chinthavali, Madhu Sudhan [ORNL; Ayers, Curtis William [ORNL; Campbell, Steven L [ORNL; Wiles, Randy H [ORNL; Ozpineci, Burak [ORNL

    2014-01-01T23:59:59.000Z

    With efforts to reduce the cost, size, and thermal management systems for the power electronics drivetrain in hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs), wide band gap semiconductors including silicon carbide (SiC) have been identified as possibly being a partial solution. This paper focuses on the development of a 10-kW all SiC inverter using a high power density, integrated printed metal power module with integrated cooling using additive manufacturing techniques. This is the first ever heat sink printed for a power electronics application. About 50% of the inverter was built using additive manufacturing techniques.

  1. Three-dimensional assemblies built up by quantum dots in size-quantization regime: Band gap shifts due to size-distribution of cadmium selenide nanoparticles

    SciTech Connect (OSTI)

    Pejova, Biljana, E-mail: biljana@pmf.ukim.mk

    2013-11-15T23:59:59.000Z

    In the present study, it is predicted that the band gap energy of a three-dimensional quantum dot assembly exhibits a red shift when the dispersion of the crystal size distribution is enlarged, even at a fixed average value thereof. The effect is manifested when the size quantization regime in individual quantum dots constituting the assembly has been entered. Under the same conditions, the sub-band gap absorption tails are characterized with large Urbach energies, which could be one or two orders of magnitude larger than the value characteristic for the non-quantized case. - Graphical abstract: Band gap shifts due to size-distribution of nanoparticles in 3D assemblies built up by quantum dots in size-quantization regime. Display Omitted - Highlights: • Optical absorption of 3D QD assemblies in size-quantization regime is modeled. • Band gap energy of the QD solid depends on the size-distribution of the nanoparticles. • QD solid samples with same ?R? exhibit band gap shift depending on size distribution. • QD size distribution leads to large Urbach energies.

  2. Hydrocarbon reaction with HF-cleaned Si(lOQ) and effects on metal-oxide-semiconductor device quality

    E-Print Network [OSTI]

    Rubloff, Gary W.

    Hydrocarbon reaction with HF-cleaned Si(lOQ) and effects on metal-oxide-semiconductor device-cleaned Si( 100) towards hydrocarbon adsorption is examined by surface analysis; most hydrocarbons adsorb oxidation after HF treatment.4'5 In this letter, passivation against hydrocarbon contamination is studied

  3. Controlling Graphene Ultrafast Hot Carrier Response from Metal-like to Semiconductor-like by Electrostatic Gating

    E-Print Network [OSTI]

    Zettl, Alex

    with dry nitrogen during the measurement. Sample preparation We grow single layer graphene on copper foil1 Controlling Graphene Ultrafast Hot Carrier Response from Metal-like to Semiconductor electro-optic sampling.2 The focused THz beam at our graphene sample has a diameter of 1 mm. For optical

  4. AlGaN/GaN Metal Oxide Semiconductor Field Effect Transistors using Titanium Dioxide P. J. HANSEN

    E-Print Network [OSTI]

    York, Robert A.

    AlGaN/GaN Metal Oxide Semiconductor Field Effect Transistors using Titanium Dioxide P. J. HANSEN 1 epitaxially on AlGaN/GaN HFET structures by molecular beam epitaxy (MBE). Growth was first performed on GaN templates to establish epitaxial growth conditions. X-ray diffraction showed [001] TiO2 || [1010]GaN

  5. Super-Resolution Mapping of Photogenerated Electron and Hole Separation in Single Metal-Semiconductor Nanocatalysts

    SciTech Connect (OSTI)

    Ha, Ji Won [Ames Laboratory; Ruberu, T. Purnima A. [Ames Laboratory; Han, Rui [Ames Laboratory; Dong, Bin [Ames Laboratory; Vela, Javier [Ames Laboratory; Fang, Ning [Ames Laboratory

    2014-01-12T23:59:59.000Z

    Metal–semiconductor heterostructures are promising visible light photocatalysts for many chemical reactions. Here, we use high-resolution superlocalization imaging to reveal the nature and photocatalytic properties of the surface reactive sites on single Au–CdS hybrid nanocatalysts. We experimentally reveal two distinct, incident energy-dependent charge separation mechanisms that result in completely opposite photogenerated reactive sites (e– and h+) and divergent energy flows on the hybrid nanocatalysts. We find that plasmon-induced hot electrons in Au are injected into the conduction band of the CdS semiconductor nanorod. The specifically designed Au-tipped CdS heterostructures with a unique geometry (two Au nanoparticles at both ends of each CdS nanorod) provide more convincing high-resolution single-turnover mapping results and clearly prove the two charge separation mechanisms. Engineering the direction of energy flow at the nanoscale can provide an efficient way to overcome important challenges in photocatalysis, such as controlling catalytic activity and selectivity. These results bear enormous potential impact on the development of better visible light photocatalysts for solar-to-chemical energy conversion.

  6. Physics of band-gap formation and its evolution in the pillar-based phononic crystal structures

    SciTech Connect (OSTI)

    Pourabolghasem, Reza; Mohammadi, Saeed; Eftekhar, Ali Asghar; Adibi, Ali [School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Khelif, Abdelkrim [Institut FEMTO-ST, Université de Franche-Comté, CNRS, 32 Avenue de l'Observatoire, 25044 Besançon Cedex (France)

    2014-07-07T23:59:59.000Z

    In this paper, the interplay of Bragg scattering and local resonance is theoretically studied in a phononic crystal (PnC) structure composed of a silicon membrane with periodic tungsten pillars. The comparison of phononic band gaps (PnBGs) in three different lattice types (i.e., square, triangular, and honeycomb) with different pillar geometries shows that different PnBGs have varying degrees of dependency on the lattice symmetry based on the interplay of the local resonances and the Bragg effect. The details of this interplay is discussed. The significance of locally resonating pillars, specially in the case of tall pillars, on PnBGs is discussed and verified by examining the PnBG position and width in perturbed lattices via Monte Carlo simulations. It is shown that the PnBGs caused by the local resonance of the pillars are more resilient to the lattice perturbations than those caused by Bragg scattering.

  7. Sharp semiconductor-to-metal transition of VO{sub 2} thin films on glass substrates

    SciTech Connect (OSTI)

    Jian, Jie; Chen, Aiping [Department of Electrical and Computer Engineering, Texas A and M University, College Station, Texas 77843-3128 (United States); Zhang, Wenrui [Material Science and Engineering Program, Texas A and M University, College Station, Texas 77843-3128 (United States); Wang, Haiyan, E-mail: wangh@ece.tamu.edu [Department of Electrical and Computer Engineering, Texas A and M University, College Station, Texas 77843-3128 (United States); Material Science and Engineering Program, Texas A and M University, College Station, Texas 77843-3128 (United States)

    2013-12-28T23:59:59.000Z

    Outstanding phase transition properties of vanadium dioxide (VO{sub 2}) thin films on amorphous glass were achieved and compared with the ones grown on c-cut sapphire and Si (111) substrates, all by pulsed laser deposition. The films on glass substrate exhibit a sharp semiconductor-to-metal transition (?4.3?°C) at a near bulk transition temperature of ?68.4?°C with an electrical resistance change as high as 3.2?×?10{sup 3} times. The excellent phase transition properties of the films on glass substrate are correlated with the large grain size and low defects density achieved. The phase transition properties of VO{sub 2} films on c-cut sapphire and Si (111) substrates were found to be limited by the high defect density.

  8. Strongly modified four-wave mixing in a coupled semiconductor quantum dot-metal nanoparticle system

    SciTech Connect (OSTI)

    Paspalakis, Emmanuel, E-mail: paspalak@upatras.gr [Materials Science Department, School of Natural Sciences, University of Patras, 265 04 Patras (Greece); Evangelou, Sofia [Materials Science Department, School of Natural Sciences, University of Patras, 265 04 Patras (Greece); Department of Materials Science and Engineering, University of Ioannina, Ioannina 45110 (Greece); Kosionis, Spyridon G.; Terzis, Andreas F. [Department of Physics, School of Natural Sciences, University of Patras, 265 04 Patras (Greece)

    2014-02-28T23:59:59.000Z

    We study the four-wave mixing effect in a coupled semiconductor quantum dot-spherical metal nanoparticle structure. Depending on the values of the pump field intensity and frequency, we find that there is a critical distance that changes the form of the spectrum. Above this distance, the four-wave mixing spectrum shows an ordinary three-peaked form and the effect of controlling its magnitude by changing the interparticle distance can be obtained. Below this critical distance, the four-wave mixing spectrum becomes single-peaked; and as the interparticle distance decreases, the spectrum is strongly suppressed. The behavior of the system is explained using the effective Rabi frequency that creates plasmonic metaresonances in the hybrid structure. In addition, the behavior of the effective Rabi frequency is explained via an analytical solution of the density matrix equations.

  9. Band-gap nonlinear optical generation: The structure of internal optical field and the structural light focusing

    SciTech Connect (OSTI)

    Zaytsev, Kirill I., E-mail: kirzay@gmail.com; Katyba, Gleb M.; Yakovlev, Egor V.; Yurchenko, Stanislav O., E-mail: st.yurchenko@mail.ru [Bauman Moscow State Technical University, 2nd Baumanskaya str. 5, Moscow 105005 (Russian Federation); Gorelik, Vladimir S. [P. N. Lebedev Physics Institute of the Russian Academy of Sciences, Leninskiy Prospekt 53, Moscow 119991 (Russian Federation)

    2014-06-07T23:59:59.000Z

    A novel approach for the enhancement of nonlinear optical effects inside globular photonic crystals (PCs) is proposed and systematically studied via numerical simulations. The enhanced optical harmonic generation is associated with two- and three-dimensional PC pumping with the wavelength corresponding to different PC band-gaps. The interactions between light and the PC are numerically simulated using the finite-difference time-domain technique for solving the Maxwell's equations. Both empty and infiltrated two-dimensional PC structures are considered. A significant enhancement of harmonic generation is predicted owing to the highly efficient PC pumping based on the structural light focusing effect inside the PC structure. It is shown that a highly efficient harmonic generation could be attained for both the empty and infiltrated two- and three-dimensional PCs. We are demonstrating the ability for two times enhancement of the parametric decay efficiency, one order enhancement of the second harmonic generation, and two order enhancement of the third harmonic generation in PC structures in comparison to the nonlinear generations in appropriate homogenous media. Obviously, the nonlinear processes should be allowed by the molecular symmetry. The criteria of the nonlinear process efficiency are specified and calculated as a function of pumping wavelength position towards the PC globule diameter. Obtained criterion curves exhibit oscillating characteristics, which indicates that the highly efficient generation corresponds to the various PC band-gap pumping. The highest efficiency of nonlinear conversions could be reached for PC pumping with femtosecond optical pulses; thus, the local peak intensity would be maximized. Possible applications of the observed phenomenon are also discussed.

  10. Differential method of analysis of luminescence spectra of semiconductors

    SciTech Connect (OSTI)

    Emel'yanov, A. M., E-mail: Emelyanov@mail.ioffe.ru [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation)

    2010-09-15T23:59:59.000Z

    A method for analyzing the luminescence spectra of semiconductors is suggested. The method is based on differentiation of the spectra. The potentialities of the method are demonstrated for luminescence in the region of the fundamental absorption edge of Si and SiGe alloy single crystals. The method is superior in accuracy to previously known luminescence methods of determining the band gap of indirect-gap semiconductors and practically insensitive to different conditions of outputting radiation from the sample.

  11. Proton-induced transient effects in a metal-semiconductor-metal (MSM) photodetector for optical-based data transfer

    SciTech Connect (OSTI)

    Marshall, C.J. [NASA/GSFC, Greenbelt, MD (United States)] [NASA/GSFC, Greenbelt, MD (United States); [NRL, Washington, DC (United States); Marshall, P.W.; Carts, M.A. [NRL, Washington, DC (United States)] [NRL, Washington, DC (United States); [SFA, Largo, MD (United States); Reed, R.A.; LaBel, K.A. [NASA/GSFC, Greenbelt, MD (United States)] [NASA/GSFC, Greenbelt, MD (United States)

    1998-12-01T23:59:59.000Z

    The authors present a study of proton transient effects in metal-semiconductor-metal (MSM) photodetectors, which demonstrates their inherent advantage for minimizing Single Event Effects (SEEs) in proton environments. Upset mechanisms are characterized for 830 nm GaAs and 1300 nm InGaAs detectors. Only protons incident at grazing angles are likely to cause a bit errors by direct ionization. The MSM technology appears to be a more robust to single bit errors than thicker 1300 nm p-i-n diode structures which the authors have previously shown to be susceptible to errors from direct ionization events at all angles, and also are relatively high optical powders. For a given receiver, the relative contributions of direct ionization and nuclear reaction upset mechanisms at a specific data rate and optical power are determined by the geometry of the charge collection volume of the detector. The authors show that state-of-the-art p-i-n detectors can also display a reduced sensitivity to direct ionization by incident protons except at grazing angles.

  12. Gallium arsenide-based ternary compounds and multi-band-gap solar cell research. Final subcontract report, 1 April 1988--31 March 1990

    SciTech Connect (OSTI)

    Vernon, S. [Spire Corp., Bedford, MA (United States)

    1993-07-01T23:59:59.000Z

    This report describes work to achieve a high-efficiency, low-cost solar cell. The basic approach to the problem is centered upon the heteroepitaxial growth of a III-V compound material onto a single-crystal silicon wafer. The growth technique employed throughout this work is metal-organic chemical vapor deposition. The silicon wafer may serve as a mechanical substrate and ohmic contact for a single-junction device, or it may contain a p-n junction of its own and form the bottom cell of a two-junction tandem solar cell structure. The III-V material for the single-junction case is GaAs, and for the two-junction case it is either GaAlAs or GaAsP, either material having the proper composition to yield a band gap of approximately 1.7 eV. Results achieved in this contract include (1) a 17.6%-efficient GaAs-on-Si solar cell; (2) an 18.5%-efficient GaAs-on-Si concentrator solar cell at 400 suns; (3) a 24.8%-efficient GaAs-on-GaAs solar cell; (4) a 28.7%-efficient GaAs-on-GaAs concentrator solar cell at 200 suns; (5) the measurement of the effects of dislocation density and emitter doping on GaAs cells; and (6) improvements in the growth process to achieve reproducible thin AlGaAs window layers with low recombination velocities and environmental stability.

  13. Development of epitaxial AlxSc1-xN for artificially structured metal/semiconductor superlattice metamaterials

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

    Sands, Timothy D.; Stach, Eric A.; Saha, Bivas; Saber, Sammy; Naik, Gururaj V.; Boltasseva, Alexandra; Kvam, Eric P.

    2015-02-01T23:59:59.000Z

    Epitaxial nitride rocksalt metal/semiconductor superlattices are emerging as a novel class of artificially structured materials that have generated significant interest in recent years for their potential application in plasmonic and thermoelectric devices. Though most nitride metals are rocksalt, nitride semiconductors in general have hexagonal crystal structure. We report rocksalt aluminum scandium nitride (Al,Sc)N alloys as the semiconducting component in epitaxial rocksalt metal/semiconductor superlattices. The AlxSc1?xN alloys when deposited directly on MgO substrates are stabilized in a homogeneous rocksalt (single) phase when x?more »has been extended to x?xSc1?xN alloys show moderate direct bandgap bowing with a bowing parameter, B?=?1.41?±?0.19?eV. The direct bandgap of metastable rocksalt AlN is extrapolated to be 4.70?±?0.20?eV. The tunable lattice parameter, bandgap, dielectric permittivity, and electronic properties of rocksalt AlxSc1?xN alloys enable high quality epitaxial rocksalt metal/AlxSc1?xN superlattices with a wide range of accessible metamaterials properties.« less

  14. On the sub-band gap optical absorption in heat treated cadmium sulphide thin film deposited on glass by chemical bath deposition technique

    SciTech Connect (OSTI)

    Chattopadhyay, P.; Karim, B.; Guha Roy, S. [Department of Electronic Science, University of Calcutta, 92, A.P.C. Road, Kolkata 700009 (India)

    2013-12-28T23:59:59.000Z

    The sub-band gap optical absorption in chemical bath deposited cadmium sulphide thin films annealed at different temperatures has been critically analyzed with special reference to Urbach relation. It has been found that the absorption co-efficient of the material in the sub-band gap region is nearly constant up to a certain critical value of the photon energy. However, as the photon energy exceeds the critical value, the absorption coefficient increases exponentially indicating the dominance of Urbach rule. The absorption coefficients in the constant absorption region and the Urbach region have been found to be sensitive to annealing temperature. A critical examination of the temperature dependence of the absorption coefficient indicates two different kinds of optical transitions to be operative in the sub-band gap region. After a careful analyses of SEM images, energy dispersive x-ray spectra, and the dc current-voltage characteristics, we conclude that the absorption spectra in the sub-band gap domain is possibly associated with optical transition processes involving deep levels and the grain boundary states of the material.

  15. Method to determine the position-dependant metal correction factor for dose-rate equivalent laser testing of semiconductor devices

    DOE Patents [OSTI]

    Horn, Kevin M.

    2013-07-09T23:59:59.000Z

    A method reconstructs the charge collection from regions beneath opaque metallization of a semiconductor device, as determined from focused laser charge collection response images, and thereby derives a dose-rate dependent correction factor for subsequent broad-area, dose-rate equivalent, laser measurements. The position- and dose-rate dependencies of the charge-collection magnitude of the device are determined empirically and can be combined with a digital reconstruction methodology to derive an accurate metal-correction factor that permits subsequent absolute dose-rate response measurements to be derived from laser measurements alone. Broad-area laser dose-rate testing can thereby be used to accurately determine the peak transient current, dose-rate response of semiconductor devices to penetrating electron, gamma- and x-ray irradiation.

  16. Size-dependent shifts of the Néel temperature and optical band-gap in NiO nanoparticles

    SciTech Connect (OSTI)

    Thota, Subhash, E-mail: mseehra@wvu.edu, E-mail: subhasht@iitg.ac.in [Department of Physics, Indian Institute of Technology, Guwahati, Assam 781039 (India); Shim, J. H.; Seehra, M. S., E-mail: mseehra@wvu.edu, E-mail: subhasht@iitg.ac.in [Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506 (United States)

    2013-12-07T23:59:59.000Z

    Bulk NiO is a well-known antiferromagnet with Neel temperature T{sub N}(?)?=?524?K and an optical band-gap E{sub g}?=?4.3?eV. With decrease in particle size D from 40?nm to 4?nm of NiO, systematic changes of T{sub N} and E{sub g} are observed and discussed here. From magnetic measurements, the changes in T{sub N} with D are found to fit finite-size scaling equation T{sub N}(D)?=?T{sub N}(?) [1 ? (?{sub o}/D){sup ?}] with ??=?3.2?±?0.5 and ?{sub o}?=?3.2?±?0.2?nm, in good agreement with the predictions for a Heisenberg system. The observed blue shifts of E{sub g} with decrease in D reaching E{sub g}?=?5.12?eV for D???4?nm are likely due to quantum confinement and non-stoichiometry.

  17. First-principles study of band gap engineering via oxygen vacancy doping in perovskite ABB'O? solid solutions

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

    Qi, Tingting; Curnan, Matthew T.; Kim, Seungchul; Bennett, Joseph W.; Grinberg, Ilya; Rappe, Andrew M.

    2011-12-01T23:59:59.000Z

    Oxygen vacancies in perovskite oxide solid solutions are fundamentally interesting and technologically important. However, experimental characterization of the vacancy locations and their impact on electronic structure is challenging. We have carried out first-principles calculations on two Zr-modified solid solutions, Pb(Zn1/3Nb2/3)O? and Pb(Mg1/3Nb2/3)O?, in which vacancies are present. We find that the vacancies are more likely to reside between low-valent cation-cation pairs than high-valent cation-cation pairs. Based on the analysis of our results, we formulate guidelines that can be used to predict the location of oxygen vacancies in perovskite solid solutions. Our results show that vacancies can have a significant impact on both the conduction and valence band energies, in some cases lowering the band gap by ?0.5 eV. The effects of vacancies on the electronic band structure can be understood within the framework of crystal field theory.

  18. Electric-field-dependent electroreflectance spectra of visible-band-gap (InAlGa)P quantum-well structures

    SciTech Connect (OSTI)

    Fritz, I.J.; Blum, O.; Schneider, R.P. Jr.; Howard, A.J.; Follstaedt, D.M. (Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States))

    1994-04-04T23:59:59.000Z

    We present results from the first studies of electric-field effects on optical transitions in visible-band-gap InGaP/InAlGaP multiple-quantum-well (MQW) structures. These structures, grown at 775 [degree]C by metalorganic vapor phase epitaxy on (100) GaAs substrates misoriented 6[degree] towards P(111)[r angle][l angle]111[r angle]A, consist of nominally undoped MQWs surrounded by doped In[sub 0.49]Al[sub 0.51]P cladding layers to form [ital p]-[ital i]-[ital n] diodes. The Stark shifts of various allowed and forbidden quantum-well transitions were observed in bias-dependent electroreflectance spectra of In[sub 0.49]Ga[sub 0.51]P/In[sub 0.49](Al[sub 0.5]Ga[sub 0.5])[sub 0.51]P MQW samples with 10-nm-thick layers. We find the magnitude of these shifts to depend on the details of the Mg doping profile, confirming the importance of Mg diffusion and unintentional background doping in these materials. Our results show that (InAlGa)P materials are promising for visible-wavelength electro-optic modulator applications.

  19. First-principles study of band gap engineering via oxygen vacancy doping in perovskite ABB'O? solid solutions

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

    Qi, Tingting; Curnan, Matthew T.; Kim, Seungchul; Bennett, Joseph W.; Grinberg, Ilya; Rappe, Andrew M.

    2011-12-01T23:59:59.000Z

    Oxygen vacancies in perovskite oxide solid solutions are fundamentally interesting and technologically important. However, experimental characterization of the vacancy locations and their impact on electronic structure is challenging. We have carried out first-principles calculations on two Zr-modified solid solutions, Pb(Zn1/3Nb2/3)O? and Pb(Mg1/3Nb2/3)O?, in which vacancies are present. We find that the vacancies are more likely to reside between low-valent cation-cation pairs than high-valent cation-cation pairs. Based on the analysis of our results, we formulate guidelines that can be used to predict the location of oxygen vacancies in perovskite solid solutions. Our results show that vacancies can have a significant impactmore »on both the conduction and valence band energies, in some cases lowering the band gap by ?0.5 eV. The effects of vacancies on the electronic band structure can be understood within the framework of crystal field theory.« less

  20. Diamond logic inverter with enhancement-mode metal-insulator-semiconductor field effect transistor

    SciTech Connect (OSTI)

    Liu, J. W., E-mail: liu.jiangwei@nims.go.jp [International Center for Young Scientists (ICYS), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Liao, M. Y.; Imura, M. [Optical and Electronic Materials Unit, NIMS, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Watanabe, E.; Oosato, H. [Nanofabrication Platform, NIMS, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Koide, Y., E-mail: koide.yasuo@nims.go.jp [Optical and Electronic Materials Unit, NIMS, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Nanofabrication Platform, NIMS, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Center of Materials Research for Low Carbon Emission, NIMS, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2014-08-25T23:59:59.000Z

    A diamond logic inverter is demonstrated using an enhancement-mode hydrogenated-diamond metal-insulator-semiconductor field effect transistor (MISFET) coupled with a load resistor. The gate insulator has a bilayer structure of a sputtering-deposited LaAlO{sub 3} layer and a thin atomic-layer-deposited Al{sub 2}O{sub 3} buffer layer. The source-drain current maximum, extrinsic transconductance, and threshold voltage of the MISFET are measured to be ?40.7?mA·mm{sup ?1}, 13.2?±?0.1?mS·mm{sup ?1}, and ?3.1?±?0.1?V, respectively. The logic inverters show distinct inversion (NOT-gate) characteristics for input voltages ranging from 4.0 to ?10.0?V. With increasing the load resistance, the gain of the logic inverter increases from 5.6 to as large as 19.4. The pulse response against the high and low input voltages shows the inversion response with the low and high output voltages.

  1. Features of an intermetallic n-ZrNiSn semiconductor heavily doped with atoms of rare-earth metals

    SciTech Connect (OSTI)

    Romaka, V. A., E-mail: vromaka@polynet.lviv.ua [National Academy of Sciences of Ukraine, Ya. Pidstryhach Institute for Applied Problems of Mechanics and Mathematics (Ukraine); Fruchart, D.; Hlil, E. K. [CNRS, Institute Neel (France); Gladyshevskii, R. E. [Ivan Franko Lviv National University (Ukraine); Gignoux, D. [CNRS, Institute Neel (France); Romaka, V. V.; Kuzhel, B. S. [Ivan Franko Lviv National University (Ukraine); Krayjvskii, R. V. [Lvivska Politechnika National University (Ukraine)

    2010-03-15T23:59:59.000Z

    The crystal structure, density of electron states, electron transport, and magnetic characteristics of an intermetallic n-ZrNiSn semiconductor heavily doped with atoms of rare-earth metals (R) have been studied in the ranges of temperatures 1.5-400 K, concentrations of rare-earth metal 9.5 x 10{sup 19}-9.5 x 10{sup 21} cm{sup -3}, and magnetic fields H {<=} 15 T. The regions of existence of Zr{sub 1-x}R{sub x}NiSn solid solutions are determined, criteria for solubility of atoms of rare-earth metals in ZrNiSn and for the insulator-metal transition are formulated, and the nature of 'a priori doping' of ZrNiSn is determined as a result of redistribution of Zr and Ni atoms at the crystallographic sites of Zr. Correlation between the concentration of the R impurity, the amplitude of modulation of the bands of continuous energies, and the degree of occupation of potential wells of small-scale fluctuations with charge carriers is established. The results are discussed in the context of the Shklovskii-Efros model of a heavily doped and compensated semiconductor.

  2. Visible-light absorption and large band-gap bowing of GaN1-xSbx from first principles

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

    Sheetz, R. Michael; Richter, Ernst; Andriotis, Antonis N.; Lisenkov, Sergey; Pendyala, Chandrashekhar; Sunkara, Mahendra K.; Menon, Madhu

    2011-08-01T23:59:59.000Z

    Applicability of the Ga(Sbx)N1-x alloys for practical realization of photoelectrochemical water splitting is investigated using first-principles density functional theory incorporating the local density approximation and generalized gradient approximation plus the Hubbard U parameter formalism. Our calculations reveal that a relatively small concentration of Sb impurities is sufficient to achieve a significant narrowing of the band gap, enabling absorption of visible light. Theoretical results predict that Ga(Sbx)N1-x alloys with 2-eV band gaps straddle the potential window at moderate to low pH values, thus indicating that dilute Ga(Sbx)N1-x alloys could be potential candidates for splitting water under visible light irradiation.

  3. Visible-light absorption and large band-gap bowing of GaN1-xSbx from first principles

    SciTech Connect (OSTI)

    Sheetz, R. Michael; Richter, Ernst; Andriotis, Antonis N.; Lisenkov, Sergey; Pendyala, Chandrashekhar; Sunkara, Mahendra K.; Menon, Madhu

    2011-08-01T23:59:59.000Z

    Applicability of the Ga(Sbx)N1-x alloys for practical realization of photoelectrochemical water splitting is investigated using first-principles density functional theory incorporating the local density approximation and generalized gradient approximation plus the Hubbard U parameter formalism. Our calculations reveal that a relatively small concentration of Sb impurities is sufficient to achieve a significant narrowing of the band gap, enabling absorption of visible light. Theoretical results predict that Ga(Sbx)N1-x alloys with 2-eV band gaps straddle the potential window at moderate to low pH values, thus indicating that dilute Ga(Sbx)N1-x alloys could be potential candidates for splitting water under visible light irradiation.

  4. Enhanced Semiconductor Nanocrystal Conductance via Solution Grown Contacts

    E-Print Network [OSTI]

    Sheldon, Matthew T.

    2010-01-01T23:59:59.000Z

    G. ; Avouris, P. , Metal-semiconductor nanocontacts: SiliconIndividual Colloidal Semiconductor Nanorods. Nano Lett 2008,Physical Chemistry of Semiconductor Nanocrystals. J. Phys.

  5. Band gap and band parameters of InN and GaN from quasiparticle energy calculations based on exact-exchange density-functional theory

    E-Print Network [OSTI]

    Band gap and band parameters of InN and GaN from quasiparticle energy calculations based on exact; published online 20 October 2006 The authors have studied the electronic structure of InN and GaN employing. © 2006 American Institute of Physics. DOI: 10.1063/1.2364469 The group III-nitrides AlN, GaN, and In

  6. Structure and red shift of optical band gap in CdO–ZnO nanocomposite synthesized by the sol gel method

    SciTech Connect (OSTI)

    Mosquera, Edgar, E-mail: edemova@ing.uchile.cl [Laboratorio de Materiales a Nanoescala, Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Tupper 2069, Santiago (Chile); Pozo, Ignacio del, E-mail: ignacio.dpf@gmail.com [Facultad de Ciencias Naturales, Matemáticas y del Medio Ambiente, Universidad Tecnológica Metropolitana, Av. José Pedro Alessandri 1242, Santiago (Chile); Morel, Mauricio, E-mail: mmorel@ing.uchile.cl [Laboratorio de Materiales a Nanoescala, Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Tupper 2069, Santiago (Chile)

    2013-10-15T23:59:59.000Z

    The structure and the optical band gap of CdO–ZnO nanocomposites were studied. Characterization using X-ray diffraction (XRD), transmission electron microscopy (TEM) and diffuse reflectance spectroscopy (DRS) analysis confirms that CdO phase is present in the nanocomposites. TEM analysis confirms the formation of spheroidal nanoparticles and nanorods. The particle size was calculated from Debey–Sherrer?s formula and corroborated by TEM images. FTIR spectroscopy shows residual organic materials (aromatic/Olefinic carbon) from nanocomposites surface. CdO content was modified in the nanocomposites in function of polyvinylalcohol (PVA) added. The optical band gap is found to be red shift from 3.21 eV to 3.11 eV with the increase of CdO content. Photoluminescence (PL) measurements reveal the existence of defects in the synthesized CdO–ZnO nanocomposites. - Graphical abstract: Optical properties of ZnO, CdO and ZnO/CdO nanoparticles. Display Omitted - Highlights: • TEM analysis confirms the presence of spherical nanoparticles and nanorods. • The CdO phase is present in the nanocomposites. • The band gap of the CdO–ZnO nanocomposites is slightly red shift with CdO content. • PL emission of CdO–ZnO nanocomposite are associated to structural defects.

  7. Mechanistic Studies of Charge Injection from Metallic Electrodes into Organic Semiconductors Mediated by Ionic Functionalities: Final Report

    SciTech Connect (OSTI)

    Nguyen, Thuc-Quyen [UCSB; Bazan, Guillermo [UCSB; Mikhailovsky, Alexander [UCSB

    2014-04-15T23:59:59.000Z

    Metal-organic semiconductor interfaces are important because of their ubiquitous role in determining the performance of modern electronics such as organic light emitting diodes (OLEDs), fuel cells, batteries, field effect transistors (FETs), and organic solar cells. Interfaces between metal electrodes required for external wiring to the device and underlying organic structures directly affect the charge carrier injection/collection efficiency in organic-based electronic devices primarily due to the mismatch between energy levels in the metal and organic semiconductor. Environmentally stable and cost-effective electrode materials, such as aluminum and gold typically exhibit high potential barriers for charge carriers injection into organic devices leading to increased operational voltages in OLEDs and FETs and reduced charge extraction in photovoltaic devices. This leads to increased power consumption by the device, reduced overall efficiency, and decreased operational lifetime. These factors represent a significant obstacle for development of next generation of cheap and energy-efficient components based on organic semiconductors. It has been noticed that introduction of organic materials with conjugated backbone and ionic pendant groups known as conjugated poly- and oligoelectrolytes (CPEs and COEs), enables one to reduce the potential barriers at the metal-organic interface and achieve more efficient operation of a device, however exact mechanisms of the phenomenon have not been understood. The goal of this project was to delineate the function of organic semiconductors with ionic groups as electron injection layers. The research incorporated a multidisciplinary approach that encompassed the creation of new materials, novel processing techniques, examination of fundamental electronic properties and the incorporation of the resulting knowledgebase into development of novel organic electronic devices with increased efficiency, environmental stability, and reduced cost. During the execution of the project, main efforts were focused on the synthesis of new charge-bearing organic materials, such as CPEs and COEs, and block copolymers with neutral and ionic segments, studies of mechanisms responsible for the charge injection modulation in devices with ionic interlayers, and use of naturally occurring charged molecules for creation of enhanced devices. The studies allowed PIs to demonstrate the usefulness of the proposed approach for the improvement of operational parameters in model OLED and FET systems resulting in increased efficiency, decreased contact resistance, and possibility to use stable metals for fabrication of device electrodes. The successful proof-of-the-principle results potentially promise development of light-weight, low fabrication cost devices which can be used in consumer applications such as displays, solar cells, and printed electronic devices. Fundamental mechanisms responsible for the phenomena observed have been identified thus advancing the fundamental knowledgebase.

  8. Dilute magnetic semiconductor and half-metal behaviour mediated by 3d transition-metal doped in black/blue phosphorene

    E-Print Network [OSTI]

    Yu, Weiyang; Niu, Chun-Yao; Li, Chong; Cho, Jun-Hyung; Jia, Yu

    2015-01-01T23:59:59.000Z

    Using first-principles calculations, we present a theoretical study of the structural, electronic and magnetic properties of 3d transition metal (TM) atoms interacting with phosphorus monovacancies in two-dimensional black/blue phosphorene. We pay special attention to the magnetic properties of these substitutional impurities and find that they can be fully understood by a simple model based on the Hund's rule. For TM-doped black phosphorene, the calculated band structures of substitutional Ti, Cr, Mn, Fe and Ni impurities show dilute magnetic semiconductor (DMS) properties while those of substitutional Sc, V and Co impurities show nonmagnetic property. For TM-doped blue phosphorene, the calculated band structures of substitutional V, Cr, Mn and Fe impurities show DMS properties, and those of substitutional Ti and Ni impurities show half-metal properties, while Sc and V impurities show nonmagnetic property. We identify three different regimes associated with the occupation of different phosphorus-metal hybrid...

  9. Disorder induced semiconductor to metal transition and modifications of grain boundaries in nanocrystalline zinc oxide thin film

    SciTech Connect (OSTI)

    Singh, Fouran; Kumar, Vinod [Materials Science Group, Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Chaudhary, Babloo [Centre of Excellence in Material Sciences and Nanomaterials, Z. H. College of Engineering and Technology, Aligarh Muslim University, Aligarh, U.P. 202001 (India); Singh, R. G. [Department of Electronic Science, Maharaja Agrasen College, University of Delhi, New Delhi 110096 (India); Kumar, Sanjeev [Materials Science Group, Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Department of Electronic Science, University of Delhi South Campus, New Delhi 110023 (India); Kapoor, A. [Department of Electronic Science, University of Delhi South Campus, New Delhi 110023 (India)

    2012-10-01T23:59:59.000Z

    This paper report on the disorder induced semiconductor to metal transition (SMT) and modifications of grain boundaries in nanocrystalline zinc oxide thin film. Disorder is induced using energetic ion irradiation. It eliminates the possibility of impurities induced transition. However, it is revealed that some critical concentration of defects is needed for inducing such kind of SMT at certain critical temperature. Above room temperature, the current-voltage characteristics in reverse bias attributes some interesting phenomenon, such as electric field induced charge transfer, charge trapping, and diffusion of defects. The transition is explained by the defects induced disorder and strain in ZnO crystallites created by high density of electronic excitations.

  10. Band-Gap Engineering of Zinc Oxide Colloids via Lattice Substitution with Sulfur Leading to Materials with Advanced Properties for

    E-Print Network [OSTI]

    Nabben, Reinhard

    gap semiconductors like III/V compounds, for instance, gallium nitride (GaN),2 or II/VI compounds bandgap of 3.37 eV at room temperature.7 Thus, one of its most elemental functions is the absorption

  11. Ballistic performance comparison of monolayer transition metal dichalcogenide MX{sub 2} (M = Mo, W; X = S, Se, Te) metal-oxide-semiconductor field effect transistors

    SciTech Connect (OSTI)

    Chang, Jiwon; Register, Leonard F.; Banerjee, Sanjay K. [Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758 (United States)

    2014-02-28T23:59:59.000Z

    We study the transport properties of monolayer MX{sub 2} (M?=?Mo, W; X?=?S, Se, Te) n- and p-channel metal-oxide-semiconductor field effect transistors (MOSFETs) using full-band ballistic non-equilibrium Green's function simulations with an atomistic tight-binding Hamiltonian with hopping potentials obtained from density functional theory. We discuss the subthreshold slope, drain-induced barrier lowering (DIBL), as well as gate-induced drain leakage (GIDL) for different monolayer MX{sub 2} MOSFETs. We also report the possibility of negative differential resistance behavior in the output characteristics of nanoscale monolayer MX{sub 2} MOSFETs.

  12. Diverse and tunable electronic structures of single-layer metal phosphorus trichalcogenides for photocatalytic water splitting

    SciTech Connect (OSTI)

    Liu, Jian [School of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan (China) [School of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan (China); Beijing Computational Science Research Center, Beijing 100084 (China); College of Electrical and Information Engineering, Hunan Institute of Engineering, Xiangtan 411105, Hunan (China); Li, Xi-Bo; Wang, Da; Liu, Li-Min, E-mail: ppeng@hnu.edu.cn, E-mail: limin.liu@csrc.ac.cn [Beijing Computational Science Research Center, Beijing 100084 (China)] [Beijing Computational Science Research Center, Beijing 100084 (China); Lau, Woon-Ming [Beijing Computational Science Research Center, Beijing 100084 (China) [Beijing Computational Science Research Center, Beijing 100084 (China); Chengdu Green Energy and Green Manufacturing Technology R and D Center, Chengdu, Sichuan 610207 (China); Peng, Ping, E-mail: ppeng@hnu.edu.cn, E-mail: limin.liu@csrc.ac.cn [School of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan (China)] [School of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan (China)

    2014-02-07T23:59:59.000Z

    The family of bulk metal phosphorus trichalcogenides (APX{sub 3}, A = M{sup II}, M{sub 0.5}{sup I}M{sub 0.5}{sup III}; X = S, Se; M{sup I}, M{sup II}, and M{sup III} represent Group-I, Group-II, and Group-III metals, respectively) has attracted great attentions because such materials not only own magnetic and ferroelectric properties, but also exhibit excellent properties in hydrogen storage and lithium battery because of the layered structures. Many layered materials have been exfoliated into two-dimensional (2D) materials, and they show distinct electronic properties compared with their bulks. Here we present a systematical study of single-layer metal phosphorus trichalcogenides by density functional theory calculations. The results show that the single layer metal phosphorus trichalcogenides have very low formation energies, which indicates that the exfoliation of single layer APX{sub 3} should not be difficult. The family of single layer metal phosphorus trichalcogenides exhibits a large range of band gaps from 1.77 to 3.94 eV, and the electronic structures are greatly affected by the metal or the chalcogenide atoms. The calculated band edges of metal phosphorus trichalcogenides further reveal that single-layer ZnPSe{sub 3}, CdPSe{sub 3}, Ag{sub 0.5}Sc{sub 0.5}PSe{sub 3}, and Ag{sub 0.5}In{sub 0.5}PX{sub 3} (X = S and Se) have both suitable band gaps for visible-light driving and sufficient over-potentials for water splitting. More fascinatingly, single-layer Ag{sub 0.5}Sc{sub 0.5}PSe{sub 3} is a direct band gap semiconductor, and the calculated optical absorption further convinces that such materials own outstanding properties for light absorption. Such results demonstrate that the single layer metal phosphorus trichalcogenides own high stability, versatile electronic properties, and high optical absorption, thus such materials have great chances to be high efficient photocatalysts for water-splitting.

  13. Intrazeolite metal carbonyl phototopotaxy: From Tungsten(VI) oxide quantum dots to a zero-dimensional semiconductor quantum supralattice

    SciTech Connect (OSTI)

    Ozin, G.A.; Oezkar, S. (Univ. of Toronto, Ontario (Canada))

    1990-09-20T23:59:59.000Z

    Attention is focused on the use of simple binary metal carbonyls for the nucleation, growth, and stabilization of intrazeolite semiconductor quantum nanostructures. The rationale for selecting this particular group of precursor molecules relates to their volatility, molecular dimensions, ease of purification, availability, and facile and quantitative conversion to the respective metal oxide materials with minimal contamination by carbon. In this study the intrazeolite photooxidation chemistry of {alpha}-cage encapsulated hexacarbonyltungsten(0) in Na{sub 56}Y and H{sub 56}Y, n(W(CO){sub 6})-Na{sub 56}Y(H{sub 56}Y), with O{sub 2} provides a novel synthetic pathway to {alpha}-cage-located tungsten(VI) oxide n(WO{sub 3})-Na{sub 56}Y(H{sub 56}Y) intrazeolite quantum dots and a zero-dimensional semiconductor quantum supralattice (where n = 0-32), which might find applications as new solid-state materials for use in quantum electronic and nonlinear optic devices.

  14. Disordered electronic and magnetic systems - transition metal (Mn) and rare earth (Gd) doped amorphous group IV semiconductors (C, Si, Ge)

    E-Print Network [OSTI]

    Zeng, Li

    2007-01-01T23:59:59.000Z

    magnetic semiconductors: the europium chalcogenides. Phys.Classic examples are europium chalcogenides [3], Gd 3?x ? xmagnetic semiconductor europium chalcogenides, where the

  15. ECE 609 Semiconductor Devices Department of Electrical and Computer Engineering

    E-Print Network [OSTI]

    Massachusetts at Amherst, University of

    ECE 609 ­ Semiconductor Devices Department of Electrical and Computer Engineering University. ________________________________________________________________________ Preliminary Course Outline 1. Overview of Semiconductor Physics 1.1 Semiconductor Materials-V Characteristics, Nonideal Behavior) 2.2 Metal Semiconductor Junctions (Schottky Barriers, Ohmic Contacts) 2

  16. Self-heating simulation of GaN-based metal-oxide-semiconductor high-electron-mobility transistors including hot electron

    E-Print Network [OSTI]

    Ye, Peide "Peter"

    Self-heating simulation of GaN-based metal-oxide-semiconductor high-electron-mobility transistors the results of self-heating simulations of the GaN-based MOS-HEMTs, including hot electron and quantum effects of the gate and source/drain extension lengths on both the output performance and self-heating is discussed

  17. Strained Ge channel p-type metal-oxide-semiconductor field-effect transistors grown on Siâ?â??xGex/Si virtual substrates

    E-Print Network [OSTI]

    Lee, Minjoo L.

    We have fabricated strained Ge channel p-type metal-oxide-semiconductor field-effect transistors (p-MOSFETs) on Siâ??.â??Geâ??.â?? virtual substrates. The poor interface between silicon dioxide (SiOâ??) and the Ge channel ...

  18. (Data in thousand metric tons of silicon content unless otherwise noted) Domestic Production and Use: Estimated value of silicon alloys and metal (excluding semiconductor-and solar-

    E-Print Network [OSTI]

    Production and Use: Estimated value of silicon alloys and metal (excluding semiconductor- and solar- grade silicon) produced in the United States in 2009 was $470 million. Four companies produced silicon materials in six plants. Of those companies, three produced ferrosilicon in four plants. Metallurgical

  19. Electron Transport Behavior on Gate Length Scaling in Sub-50 nm GaAs Metal Semiconductor Field Effect Transistors

    SciTech Connect (OSTI)

    Han, Jaeheon [Department of Electronic Engineering, Kangnam University, 111 Gugal-dong, Giheung-gu, Yongin-city, Gyeonggi-do, Korea 446-702 (Korea, Republic of)

    2011-12-23T23:59:59.000Z

    Short channel GaAs Metal Semiconductor Field Effect Transistors (MESFETs) have been fabricated with gate length to 20 nm, in order to examine the characteristics of sub-50 nm MESFET scaling. Here the rise in the measured transconductance is mainly attributed to electron velocity overshoot. For gate lengths below 40 nm, however, the transconductance drops suddenly. The behavior of velocity overshoot and its degradation is investigated and simulated by using a transport model based on the retarded Langevin equation (RLE). This indicates the existence of a minimum acceleration length needed for the carriers to reach the overshoot velocity. The argument shows that the source resistance must be included as an internal element, or appropriate boundary condition, of relative importance in any model where the gate length is comparable to the inelastic mean free path of the carriers.

  20. Experimental study on vertical scaling of InAs-on-insulator metal-oxide-semiconductor field-effect transistors

    SciTech Connect (OSTI)

    Kim, SangHyeon, E-mail: dadembyora@mosfet.t.u-tokyo.ac.jp, E-mail: sh-kim@kist.re.kr; Yokoyama, Masafumi; Nakane, Ryosho; Takenaka, Mitsuru; Takagi, Shinichi [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Ichikawa, Osamu; Osada, Takenori; Hata, Masahiko [Sumitomo Chemical Co., Ltd., 6 Kitahara, Tsukuba, Ibaraki 300-3294 (Japan)

    2014-06-30T23:59:59.000Z

    We have investigated effects of the vertical scaling on electrical properties in extremely thin-body InAs-on-insulator (-OI) metal-oxide-semiconductor field-effect transistors (MOSFETs). It is found that the body thickness (T{sub body}) scaling provides better short channel effect (SCE) control, whereas the T{sub body} scaling also causes the reduction of the mobility limited by channel thickness fluctuation (?T{sub body}) scattering (?{sub fluctuation}). Also, in order to achieve better SCEs control, the thickness of InAs channel layer (T{sub channel}) scaling is more favorable than the thickness of MOS interface buffer layer (T{sub buffer}) scaling from a viewpoint of a balance between SCEs control and ?{sub fluctuation} reduction. These results indicate necessity of quantum well channel structure in InAs-OI MOSFETs and these should be considered in future transistor design.

  1. Semiconductor-metal phase transition of vanadium dioxide nanostructures on silicon substrate: Applications for thermal control of spacecraft

    SciTech Connect (OSTI)

    Leahu, G. L., E-mail: roberto.livoti@uniroma1.it; Li Voti, R., E-mail: roberto.livoti@uniroma1.it; Larciprete, M. C., E-mail: roberto.livoti@uniroma1.it; Belardini, A., E-mail: roberto.livoti@uniroma1.it; Mura, F., E-mail: roberto.livoti@uniroma1.it; Sibilia, C.; Bertolotti, M. [Dipartimento di Scienze di Base ed Applicate per l'Ingegneria, Sapienza Università di Roma, Via A. Scarpa 16 00161 Roma (Italy); Fratoddi, I. [Dipartimento di Chimica, Sapienza Università di Roma, Piazzale A. Moro, Roma (Italy)

    2014-06-19T23:59:59.000Z

    We present a detailed infrared study of the semiconductor-to-metal transition (SMT) in a vanadium dioxide (VO2) film deposited on silicon wafer. The VO2 phase transition is studied in the mid-infrared (MIR) region by analyzing the transmittance and the reflectance measurements, and the calculated emissivity. The temperature behaviour of the emissivity during the SMT put into evidence the phenomenon of the anomalous absorption in VO2 which has been explained by applying the Maxwell Garnett effective medium approximation theory, together with a strong hysteresis phenomenon, both useful to design tunable thermal devices to be applied for the thermal control of spacecraft. We have also applied the photothermal radiometry in order to study the changes in the modulated emissivity induced by laser. Experimental results show how the use of these techniques represent a good tool for a quantitative measurement of the optothermal properties of vanadium dioxide based structures.

  2. Photo-response of a P3HT:PCBM blend in metal-insulator-semiconductor capacitors

    SciTech Connect (OSTI)

    Devynck, M.; Rostirolla, B.; Watson, C. P.; Taylor, D. M., E-mail: d.m.taylor@bangor.ac.uk [School of Electronic Engineering, Bangor University, Dean Street, Bangor, Gwynedd LL57 1UT (United Kingdom)

    2014-11-03T23:59:59.000Z

    Metal-insulator-semiconductor capacitors are investigated, in which the insulator is cross-linked polyvinylphenol and the active layer a blend of poly(3-hexylthiophene), P3HT, and the electron acceptor [6,6]-phenyl-C{sub 61}-butyric acid methyl ester (PCBM). Admittance spectra and capacitance-voltage measurements obtained in the dark both display similar behaviour to those previously observed in P3HT-only devices. However, the photo-capacitance response is significantly enhanced in the P3HT:PCBM case, where exciton dissociation leads to electron transfer into the PCBM component. The results are consistent with a network of PCBM aggregates that is continuous through the film but with no lateral interconnection between the aggregates at or near the blend/insulator interface.

  3. Resonant charge transfer of hydrogen Rydberg atoms incident at a Cu(100) projected band-gap surface

    E-Print Network [OSTI]

    Gibbard, J A; Kohlhoff, M; Rennick, C J; So, E; Ford, M; Softley, T P

    2015-01-01T23:59:59.000Z

    The charge transfer (ionization) of hydrogen Rydberg atoms (principal quantum number $n=25-34$) incident at a Cu(100) surface is investigated. Unlike fully metallic surfaces, where the Rydberg electron energy is degenerate with the conduction band of the metal, the Cu(100) surface has a projected bandgap at these energies, and only discrete image states are available through which charge transfer can take place. Resonant enhancement of charge transfer is observed at hydrogen principal quantum numbers for which the Rydberg energy matches the energy of one of the image states. The integrated surface ionization signals show clear periodicity as the energies of states with increasing $n$ come in and out of resonance with the image states. The velocity dependence of the surface ionization dynamics is also investigated. Decreased velocity of the incident H atom leads to a greater mean distance of ionization and a lower field required to extract the ion. The surface-ionization profiles (signal versus applied field) ...

  4. Direct band gap optical emission from compressively strained Ge films grown on relaxed Si{sub 0.5}Ge{sub 0.5} substrate

    SciTech Connect (OSTI)

    Aluguri, R.; Manna, S.; Ray, S. K. [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)] [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)

    2013-10-14T23:59:59.000Z

    Compressively strained Ge films have been grown on relaxed Si{sub 0.5}Ge{sub 0.5} virtual substrate in ultra high vacuum using molecular beam epitaxy. Structural characterization has shown that the Ge films are compressively strained with partial strain relaxation in a film thicker than 3.0 nm, due to onset of island nucleation. Photoluminescence spectra exhibit the splitting of degenerate Ge valence band into heavy hole and light hole bands with a broad direct band gap emission peak around 0.81 eV. Temperature and excitation power dependent emission characteristics have been studied to investigate the mechanism of luminescence quenching at high temperatures and the role of non-radiative recombination centers.

  5. Band gap engineering of In{sub 2}O{sub 3} by alloying with Tl{sub 2}O{sub 3}

    SciTech Connect (OSTI)

    Scanlon, David O., E-mail: d.scanlon@ucl.ac.uk [Kathleen Lonsdale Materials Chemistry, Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Regoutz, Anna; Egdell, Russell G. [Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR (United Kingdom)] [Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR (United Kingdom); Morgan, David J. [Cardiff Catalysis Institute (CCI), School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT (United Kingdom)] [Cardiff Catalysis Institute (CCI), School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT (United Kingdom); Watson, Graeme W. [School of Chemistry and CRANN, Trinity College Dublin, Dublin 2 (Ireland)] [School of Chemistry and CRANN, Trinity College Dublin, Dublin 2 (Ireland)

    2013-12-23T23:59:59.000Z

    Efficient modulation of the bandgap of In{sub 2}O{sub 3} will open up a route to improved electronic properties. We demonstrate using ab initio calculations that Tl incorporation into In{sub 2}O{sub 3} reduces the band gap and confirm that narrowing of the gap is observed by X-ray photoemission spectroscopy on ceramic surfaces. Incorporation of Tl does not break the symmetry of the allowed optical transitions, meaning that the doped thin films should retain optical transparency in the visible region, in combination with a lowering of the conduction band effective mass. We propose that Tl-doping may be an efficient way to increase the dopability and carrier mobility of In{sub 2}O{sub 3}.

  6. Optical and structural study of GaN nanowires grown by catalyst-free molecular beam epitaxy. II. Sub-band-gap luminescence and electron irradiation effects

    SciTech Connect (OSTI)

    Robins, Lawrence H.; Bertness, Kris A.; Barker, Joy M.; Sanford, Norman A.; Schlager, John B. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); National Institute of Standards and Technology, Boulder, Colorado 80305 (United States)

    2007-06-01T23:59:59.000Z

    GaN nanowires with diameters of 50-250 nm, grown by catalyst-free molecular beam epitaxy, were characterized by photoluminescence (PL) and cathodoluminescence (CL) spectroscopy at temperatures from 3 to 297 K. Both as-grown samples and dispersions of the nanowires onto other substrates were examined. The properties of the near-band-edge PL and CL spectra were discussed in Part I of this study by [Robins et al. [L. H. Robins, K. A. Bertness, J. M. Barker, N. A. Sanford, and J. B. Schlager, J. Appl. Phys. 101,113505 (2007)]. Spectral features below the band gap, and the effect of extended electron irradiation on the CL, are discussed in Part II. The observed sub-band-gap PL and CL peaks are identified as phonon replicas of the free-exciton transitions, or excitons bound to structural defects or surface states. The defect-related peaks in the nanowires are correlated with luminescence lines previously reported in GaN films, denoted the Y lines [M. A. Reshchikov and H. Morkoc, J. Appl. Phys. 97, 061301 (2005)]. The CL was partially quenched by electron beam irradiation for an extended time; the quenching was stronger for the free and shallow-donor-bound exciton peaks than for the defect-related peaks. The quenching appeared to saturate at high irradiation dose (with final intensity {approx_equal}30% of initial intensity) and was reversible on thermal cycling to room temperature. The electron irradiation-induced quenching of the CL is ascribed to charge injection and trapping phenomena.

  7. Direct observation of both contact and remote oxygen scavenging of GeO{sub 2} in a metal-oxide-semiconductor stack

    SciTech Connect (OSTI)

    Fadida, S., E-mail: sivanfa@tx.technion.ac.il; Shekhter, P.; Eizenberg, M. [Department of Materials Science and Engineering, Technion-Israel Institute of Technology, Haifa (Israel); Cvetko, D. [Laboratorio TASC/IOM-CNR, Area di ricerca, Trieste (Italy); Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana (Slovenia); Floreano, L.; Verdini, A. [Laboratorio TASC/IOM-CNR, Area di ricerca, Trieste (Italy); Nyns, L.; Van Elshocht, S. [Imec, Kapeldreef 75, B-3001 Leuven (Belgium); Kymissis, I. [Department of Electrical Engineering, Columbia University, New York, New York 10027 (United States)

    2014-10-28T23:59:59.000Z

    In the path to incorporating Ge based metal-oxide-semiconductor into modern nano-electronics, one of the main issues is the oxide-semiconductor interface quality. Here, the reactivity of Ti on Ge stacks and the scavenging effect of Ti were studied using synchrotron X-ray photoelectron spectroscopy measurements, with an in-situ metal deposition and high resolution transmission electron microscopy imaging. Oxygen removal from the Ge surface was observed both in direct contact as well as remotely through an Al{sub 2}O{sub 3} layer. The scavenging effect was studied in situ at room temperature and after annealing. We find that the reactivity of Ti can be utilized for improved scaling of Ge based devices.

  8. Hybrid density functional calculations of the band gap of GaxIn1-xN Xifan Wu,1 Eric J. Walter,2 Andrew M. Rappe,3 Roberto Car,1 and Annabella Selloni1

    E-Print Network [OSTI]

    Rappe, Andrew M.

    Hybrid density functional calculations of the band gap of GaxIn1-xN Xifan Wu,1 Eric J. Walter,2 Andrew M. Rappe,3 Roberto Car,1 and Annabella Selloni1 1Chemistry Department, Princeton University Recent theoretical work has provided evidence that hybrid functionals, which include a fraction of exact

  9. VOLUME 84, NUMBER 19 P H Y S I C A L R E V I E W L E T T E R S 8 MAY 2000 Theory and Experiments on Elastic Band Gaps

    E-Print Network [OSTI]

    Investigaciones Científicas (CSIC), Serrano 144, 28006 Madrid, Spain 2 Ames Laboratory, Iowa State University, Ames, Iowa 50011 3 Instituto de Acústica, CSIC, Serrano 144, 28006 Madrid, Spain 4 Instituto de Física Aplicada, CSIC, Serrano 144, 28006 Madrid, Spain (Received 26 February 1999) We study elastic band gaps

  10. The Study of Energy Band Gap of In{sub x}Al{sub y}Ga{sub 1-x-y}N Quaternary Alloys using UV-VIS Spectroscopy

    SciTech Connect (OSTI)

    Raof, N. H. Abd.; Ng, S. S.; Hassan, H. Abu; Hassan, Z. [Nano-Optoelectronics Research Laboratory, School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2009-06-01T23:59:59.000Z

    Quaternary In{sub x}Al{sub y}Ga{sub 1-x-y}N alloys with indium (In) mole fraction x ranging from 0.01 to 0.10 and constant aluminum (Al) mole fraction y = 0.06, were grown by molecular beam epitaxy. The energy band gaps of InAlGaN alloys were investigated using UV-VIS spectroscopy under room temperature. The energy band gap decreases with increasing In composition from 0.01 to 0.08. This trend is expected since the incorporation of In lowers the energy band gap of Al{sub 0.06}Ga{sub 0.94}N(3.72 eV). However, for InAlGaN with In composition of 0.1, the band gap shows a sudden increase in energy. This is probably due to local alloy compositional fluctuations in the epilayer, contributed by incomplete substitutions of Ga atoms by the In atoms, thus retaining a much richer GaN structure. Finally, we investigate the bowing parameter appears also to be very sensitive on In content. We obtained b 50.08 for quaternary InAlGaN alloys.

  11. Metal-dependent Fermi-level movement in the metal/sulfur-passivated InGaP contact

    E-Print Network [OSTI]

    Kim, Sehun

    Metal-dependent Fermi-level movement in the metal/sulfur-passivated InGaP contact Y. K. Kim formed on S-passivated n-InGaP 100 surface reveals that the species produced by the chemical reaction. The initial sulfur passivation of n-InGaP 100 surface efficiently reduced the gap states within the band gap

  12. Band-Gap Reduction and Dopant Interaction in Epitaxial La,Cr Co-doped SrTiO3 Thin Films

    SciTech Connect (OSTI)

    Comes, Ryan B.; Sushko, Petr; Heald, Steve M.; Colby, Robert J.; Bowden, Mark E.; Chambers, Scott A.

    2014-12-03T23:59:59.000Z

    We show that by co-doping SrTiO3 (STO) epitaxial thin films with equal amounts of La and Cr it is possible to produce films with an optical band gap ~0.9 eV lower than that of undoped STO. Sr1-xLaxTi1-xCrxO3 thin films were deposited by molecular beam epitaxy and characterized using x-ray photoelectron spectroscopy and x-ray absorption near-edge spectroscopy to show that the Cr dopants are almost exclusively in the Cr3+ oxidation state. Extended x-ray absorption fine structure measurements and theoretical modeling suggest that it is thermodynamically preferred for La and Cr dopants to occupy nearest neighbor A- and B-sites in the lattice. Transport measurements show that the material exhibits variable-range hopping conductivity with high resistivity. These results create new opportunities for the use of doped STO films in photovoltaic and photocatalytic applications.

  13. Gallium arsenide-based ternary compounds and multi-band-gap solar cell research. Annual subcontract report, 15 April 1988--14 June 1990

    SciTech Connect (OSTI)

    Vernon, S. [Spire Corp., Bedford, MA (United States)

    1993-02-01T23:59:59.000Z

    Aim of this contract is the achievement of a high-efficiency, low-cost solar cell. The basic approach to the problem is centered upon the heteroepitaxial growth of a III-V compound material onto a single-crystal silicon wafer. The growth technique employed is metalorganic chemical vapor deposition. The silicon wafer may serve as a mechanical substrate and ohmic contact for a single-junction device, or may contain a p-n junction of its own and form the bottom cell of a two junction tandem solar cell structure. The III-V material for the single-junction case is GaAs and for the two-junction case is either GaAlAs or GaAsP, either material having the proper composition to yield a band gap of approximately 1.7 eV. Results achieved in this contract include the following: (1) a 17.6% efficient GaAs-on-Si solar cell; (2) an 18.5% efficient GaAs-on-Si concentrator solar cell at 400 suns; (3) a 24.8% efficient GaAs-on-GaAs solar cell; (4) a 28.7% efficient GaAs-on-GaAs concentrator solar cell at 200 suns; (5) measurement of the effects of dislocation density and emitter doping on GaAs cells; and (6) improvements in the growth process to achieve reproducible thin AlGaAs window layers with low recombination velocities and environmental stability.

  14. OPTI 240: Semiconductor Physics and Lasers Instructor: Mahmoud Fallahi

    E-Print Network [OSTI]

    Arizona, University of

    OPTI 240: Semiconductor Physics and Lasers Instructor: Mahmoud Fallahi fallahi@optics.arizona.edu Spring Semester Introduction to Semiconductor Optoelectronic Introduction to quantum mechanics: Energy exclusion principle Metal, Insulator, Semiconductor Conduction band, valance band, energy gap Electrons

  15. Study of gate oxide traps in HfO[subscript 2]/AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors by use of ac transconductance method

    E-Print Network [OSTI]

    Sun, X.

    We introduce an ac-transconductance method to profile the gate oxide traps in a HfO[subscript 2] gated AlGaN/GaN Metal-Oxide-Semiconductor High-Electron-Mobility Transistors (MOS-HEMTs) that can exchange carriers with metal ...

  16. Metal-semiconductor-transition observed in Bi{sub 2}Ca(Sr, Ba){sub 2}Co{sub 2}O{sub 8+?} single crystals

    SciTech Connect (OSTI)

    Dong, Song-Tao [National Laboratory of Solid State Microstructures and Department of Material Science and Engineering, Nanjing University, Nanjing 210093 (China); Institute of Material Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003 (China); Zhang, Bin-Bin; Zhang, Lun-Yong; Yao, Shu-Hua, E-mail: ybchen@nju.edu.cn, E-mail: shyao@nju.edu.cn; Zhou, Jian; Zhang, Shan-Tao; Gu, Zheng-Bin; Chen, Yan-Feng [National Laboratory of Solid State Microstructures and Department of Material Science and Engineering, Nanjing University, Nanjing 210093 (China); Chen, Y. B., E-mail: ybchen@nju.edu.cn, E-mail: shyao@nju.edu.cn [National Laboratory of Solid State Microstructures and Department of Physics and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2014-07-28T23:59:59.000Z

    Electrical property evolution of Bi{sub 2}AE{sub 2}Co{sub 2}O{sub 8+?} single crystals (AE?=?Ca, Sr and Ba) is systematically explored. When AE changes from Ca to Ba, the electrical property of Bi{sub 2}Ca{sub 2}Co{sub 2}O{sub 8+?} and Bi{sub 2}Sr{sub 2}Co{sub 2}O{sub 8+?} demonstrates semiconductor-like properties. But Bi{sub 2}Ba{sub 2}Co{sub 2}O{sub 8+?} shows the metallic behavior. Analysis of temperature-dependent resistance substantiates that from metallic Bi{sub 2}Ba{sub 2}Co{sub 2}O{sub 8+?} to semiconductor-like Bi{sub 2}Sr{sub 2}Co{sub 2}O{sub 8+?} can be attributed to Anderson localization. However the semiconductor behaviour of Bi{sub 2}Sr{sub 2}Co{sub 2}O{sub 8+?} and Bi{sub 2}Ca{sub 2}Co{sub 2}O{sub 8+?} is related to electronic correlations effect that is inferred by large negative magnetoresistance (?70%). The theoretical electronic structures and valence X-ray photoemission spectroscopy substantiate that there is a relative large density of state around Fermi level in Bi{sub 2}Ba{sub 2}Co{sub 2}O{sub 8+?} compared with other two compounds. It suggests that Bi{sub 2}Ba{sub 2}Co{sub 2}O{sub 8+?} is more apt to be metal in this material system.

  17. Anomalous output characteristic shift for the n-type lateral diffused metal-oxide-semiconductor transistor with floating P-top layer

    SciTech Connect (OSTI)

    Liu, Siyang; Zhang, Chunwei; Sun, Weifeng, E-mail: swffrog@seu.edu.cn [National ASIC System Engineering Research Center, Southeast University, Nanjing 210096 (China); Su, Wei; Wang, Shaorong; Ma, Shulang; Huang, Yu [CSMC Technologies Corporation, Wuxi 214061 (China)

    2014-04-14T23:59:59.000Z

    Anomalous output characteristic shift of the n-type lateral diffused metal-oxide-semiconductor transistor with floating P-top layer is investigated. It shows that the linear drain current has obvious decrease when the output characteristic of fresh device is measured for two consecutive times. The charge pumping experiments demonstrate that the decrease is not from hot-carrier degradation. The reduction of cross section area for the current flowing, which results from the squeezing of the depletion region surrounding the P-top layer, is responsible for the shift. Consequently, the current capability of this special device should be evaluated by the second measured output characteristic.

  18. An in-depth noise model for giant magnetoresistance current sensors for circuit design and complementary metal–oxide–semiconductor integration

    SciTech Connect (OSTI)

    Roldán, A., E-mail: amroldan@ugr.es; Roldán, J. B. [Department of Electronics and Computer Technology, University of Granada (Spain); Reig, C. [Department of Electronic Engineering, University of Valencia (Spain); Cardoso, S. [INESC-MN and IN, Rua Alves Redol 9, 1000-029 Lisbon (Portugal); Instituto Superior Técnico (IST), Av. Rovisco Pais, 1000-029 Lisbon (Portugal); Cardoso, F. [INESC-MN and IN, Rua Alves Redol 9, 1000-029 Lisbon (Portugal); Ferreira, R. [International Iberian Nanotechnology Laboratory, Braga (Portugal); Freitas, P. P. [INESC-MN and IN, Rua Alves Redol 9, 1000-029 Lisbon (Portugal); International Iberian Nanotechnology Laboratory, Braga (Portugal)

    2014-05-07T23:59:59.000Z

    Full instrumentation bridges based on spin valve of giant magnetoresistance and magnetic tunnel junction devices have been microfabricated and experimentally characterized from the DC and noise viewpoint. A more realistic model of these devices was obtained in this work, an electrical and thermal model previously developed have been improved in such a way that noise effects are also included. We have implemented the model in a circuit simulator and reproduced the experimental measurements accurately. This provides a more realistic and complete tool for circuit design where magnetoresistive elements are combined with well-known complementary metal–oxide–semiconductor modules.

  19. Grain size effect on the semiconductor-metal phase transition characteristics of magnetron-sputtered VO{sub 2} thin films

    SciTech Connect (OSTI)

    Brassard, D.; Fourmaux, S.; Jean-Jacques, M.; Kieffer, J.C.; El Khakani, M. A. [Institut National de la Recherche Scientifique, INRS-Energie, Materiaux et Telecommunications, 1650, Boulevard Lionel-Boulet, C.P. 1020, Varennes, Quebec, J3X 1S2 (Canada)

    2005-08-01T23:59:59.000Z

    Single-phase vanadium dioxide (VO{sub 2}) thin films have been grown on Si{sub 3}N{sub 4}/Si substrates by means of a well-controlled magnetron sputtering process. The deposited VO{sub 2} films were found to exhibit a semiconductor-to-metal transition (SMT) at {approx}69 deg. C with a resistivity change as high as 3.2 decades. A direct and clear-cut correlation is established between the SMT characteristics (both amplitude and abruptness of the transition) of the VO{sub 2} films and their crystallite size.

  20. EEE 6397 Semiconductor Device Theory (Fall, 2014, 5th

    E-Print Network [OSTI]

    Fang, Yuguang "Michael"

    1 EEE 6397 Semiconductor Device Theory (Fall, 2014, 5th period MWF, BEN328) Goals: (1) Develop fundamental understanding on the device physics of the most important semiconductor devices, such as PN junctions, metal-semiconductor contacts, metal-oxide-semiconductor capacitors, and field-effect transistors

  1. Band gap modification and ferroelectric properties of Bi{sub 0.5}(Na,K){sub 0.5}TiO{sub 3}-based by Li substitution

    SciTech Connect (OSTI)

    Quan, Ngo Duc [Department of General Physics, School of Engineering Physics, Ha Noi University of Science and Technology, 1 Dai Co Viet road, Ha Noi (Viet Nam) [Department of General Physics, School of Engineering Physics, Ha Noi University of Science and Technology, 1 Dai Co Viet road, Ha Noi (Viet Nam); International Training Institute for Materials Science, Hanoi University of Science and Technology, 1 Dai Co Viet road, Hanoi (Viet Nam); Hung, Vu Ngoc [International Training Institute for Materials Science, Hanoi University of Science and Technology, 1 Dai Co Viet road, Hanoi (Viet Nam)] [International Training Institute for Materials Science, Hanoi University of Science and Technology, 1 Dai Co Viet road, Hanoi (Viet Nam); Quyet, Nguyen Van [Hanautech Co., Ltd., 832, Tamnip-dong, Yuseong-gu, Daejeon (Korea, Republic of)] [Hanautech Co., Ltd., 832, Tamnip-dong, Yuseong-gu, Daejeon (Korea, Republic of); Chung, Hoang Vu [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet street, Hanoi (Viet Nam)] [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet street, Hanoi (Viet Nam); Dung, Dang Duc, E-mail: dung.dangduc@hust.edu.vn [Department of General Physics, School of Engineering Physics, Ha Noi University of Science and Technology, 1 Dai Co Viet road, Ha Noi (Viet Nam)

    2014-01-15T23:59:59.000Z

    We report on the reduction of band gap in Bi{sub 0.5}(Na{sub 0.82-x}Li{sub x}K{sub 0.18}){sub 0.5}(Ti{sub 0.95}Sn{sub 0.05})O{sub 3} from 2.99 eV to 2.84 eV due to the substitutions of Li{sup +} ions to Na{sup +} sites. In addition, the lithium substitution samples exhibit an increasing of the maximal polarizations from 21.8 to 25.7 ?C/cm{sup 2}. The polarization enhancement of ferroelectric and reduction of the band gaps are strongly related to the Li substitution concentration as evaluated via the electronegative between A-site and oxygen and tolerance factor. The results are promising for photovoltaic and photocatalytic applications.

  2. Disordered electronic and magnetic systems - transition metal (Mn) and rare earth (Gd) doped amorphous group IV semiconductors (C, Si, Ge)

    E-Print Network [OSTI]

    Zeng, Li

    2007-01-01T23:59:59.000Z

    various transition or rare-earth metals provide a rich ?eldTransition Metal (Mn) and Rare Earth (Gd) Doped AmorphousTransition Metal (Mn) and Rare Earth (Gd) Doped Amorphous

  3. Pressure-driven semiconductor-metal transition in intermediate-valence TmSe sub 1 minus x Te sub x and the concept of an excitonic insulator

    SciTech Connect (OSTI)

    Neuenschwander, J.; Wachter, P. (Laboratorium fuer Festkoerperphysik, Eidgenoessische Technische Hochschule Zuerich, CH-8093 Zuerich (Switzerland))

    1990-06-15T23:59:59.000Z

    This work studies the pressure-induced semiconductor-to-metal transition (SMT) in the TmSe-TmTe alloy system. This SMT is accompanied by a valence instability of the Tm ions. Single-crystalline semiconducting TmSe{sub 1{minus}{ital x}}Te{sub {ital x}} alloys are investigated under high pressure at low temperatures. Measurements of electrical resistivity, magnetic susceptibility, neutron diffraction, and optical properties are presented and discussed. A very unusual peak structure in the resistivity-pressure relation is observed at low temperatures. A discussion of the novel feature involves the concept of an excitonic insulator and {ital f}-{ital d} hybridization. The magnetic behavior of the compounds is significantly influenced by the SMT. This is thought to be mainly due to the additional coupling between the magnetic moments of Tm via free carriers which are present in the metallic state.

  4. Temperature dependent junction capacitance-voltage characteristics of Ni embedded TiN/SiO{sub 2}/p-Si metal–insulator–semiconductor structure

    SciTech Connect (OSTI)

    Panda, J.; Nath, T. K., E-mail: tnath@phy.iitkgp.ernet.in [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302 (India); Chattopadhyay, S. [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302 (India); Amity Institute of Nano Technology, Amity University, Sector-125, Noida, Uttar Pradesh 201313 (India)

    2013-12-14T23:59:59.000Z

    This work presents the junction capacitance–voltage characteristics of highly textured/epitaxial Ni nanoparticle embedded in TiN matrix (TiN(Ni)) metal-insulator-semiconductor TiN(Ni)/SiO{sub 2}/p-Si (100) heterojunction in the temperature range of 10–300?K. This heterojunction behaves as metal-semiconductor junction with unavoidable leakage through native oxide SiO{sub 2} layer. The clockwise hysteresis loop has been observed in the capacitance-voltage characteristics measured at various frequencies mainly due to presence of trap centers at the TiN(Ni)/SiO{sub 2} interface and these are temperature dependent. The spin-dependent trap charge effect at the interface influences the quadratic nature of the capacitance with magnetic field. The junction magnetocapacitance (JMC) is observed to be dependent on both temperature and frequency. The highest JMC of this heterojunction has been observed at 200?K at higher frequencies (100?kHz–1?MHz). It is found that there is not much effect of band structure modification under magnetic field causing the JMC.

  5. Process for producing chalcogenide semiconductors

    DOE Patents [OSTI]

    Noufi, R.; Chen, Y.W.

    1985-04-30T23:59:59.000Z

    A process for producing chalcogenide semiconductor material is disclosed. The process includes forming a base metal layer and then contacting this layer with a solution having a low pH and containing ions from at least one chalcogen to chalcogenize the layer and form the chalcogenide semiconductor material.

  6. Process for producing chalcogenide semiconductors

    DOE Patents [OSTI]

    Noufi, Rommel (Westminster, CO); Chen, Yih-Wen (Omaha, NE)

    1987-01-01T23:59:59.000Z

    A process for producing chalcogenide semiconductor material is disclosed. The process includes forming a base metal layer and then contacting this layer with a solution having a low pH and containing ions from at least one chalcogen to chalcogenize the layer and form the chalcogenide semiconductor material.

  7. Low trap states in in situ SiN{sub x}/AlN/GaN metal-insulator-semiconductor structures grown by metal-organic chemical vapor deposition

    SciTech Connect (OSTI)

    Lu, Xing; Ma, Jun; Jiang, Huaxing; Liu, Chao; Lau, Kei May, E-mail: eekmlau@ust.hk [Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

    2014-09-08T23:59:59.000Z

    We report the use of SiN{sub x} grown in situ by metal-organic chemical vapor deposition as the gate dielectric for AlN/GaN metal-insulator-semiconductor (MIS) structures. Two kinds of trap states with different time constants were identified and characterized. In particular, the SiN{sub x}/AlN interface exhibits remarkably low trap state densities in the range of 10{sup 11}–10{sup 12?}cm{sup ?2}eV{sup ?1}. Transmission electron microscopy and X-ray photoelectron spectroscopy analyses revealed that the in situ SiN{sub x} layer can provide excellent passivation without causing chemical degradation to the AlN surface. These results imply the great potential of in situ SiN{sub x} as an effective gate dielectric for AlN/GaN MIS devices.

  8. Strained Sistrained Ge dual-channel heterostructures on relaxed Si0.5Ge0.5 for symmetric mobility p-type and n-type metal-oxide-semiconductor

    E-Print Network [OSTI]

    Strained SiÕstrained Ge dual-channel heterostructures on relaxed Si0.5Ge0.5 for symmetric mobility By growing heterostructures that combine a surface strained Si layer with a buried strained Ge layer on Si0.5Ge0.5 , we have fabricated metal-oxide-semiconductor field-effect transistors with mobility

  9. Structural phase transition, narrow band gap, and room-temperature ferromagnetism in [KNbO{sub 3}]{sub 1?x}[BaNi{sub 1/2}Nb{sub 1/2}O{sub 3??}]{sub x} ferroelectrics

    SciTech Connect (OSTI)

    Zhou, Wenliang; Yang, Pingxiong, E-mail: pxyang@ee.ecnu.edu.cn; Chu, Junhao [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China); Deng, Hongmei [Instrumental Analysis and Research Center, Institute of Materials, Shanghai University, 99 Shangda Road, Shanghai 200444 (China)

    2014-09-15T23:59:59.000Z

    Structural phase transition, narrow band gap (E{sub g}), and room-temperature ferromagnetism (RTFM) have been observed in the [KNbO{sub 3}]{sub 1?x}[BaNi{sub 1/2}Nb{sub 1/2}O{sub 3??}]{sub x} (KBNNO) ceramics. All the samples have single phase perovskite structure, but exhibit a gradual transition behaviour from the orthorhombic to a cubic structure with the increase of x. Raman spectroscopy analysis not only corroborates this doping-induced change in normal structure but also shows the local crystal symmetry for x ? 0.1 compositions to deviate from the idealized cubic perovskite structure. A possible mechanism for the observed specific changes in lattice structure is discussed. Moreover, it is noted that KBNNO with compositions x?=?0.1–0.3 have quite narrow E{sub g} of below 1.5?eV, much smaller than the 3.2?eV band gap of parent KNbO{sub 3} (KNO), which is due to the increasing Ni 3d electronic states within the gap of KNO. Furthermore, the KBNNO materials present RTFM near a tetragonal to cubic phase boundary. With increasing x from 0 to 0.3, the magnetism of the samples develops from diamagnetism to ferromagnetism and paramagnetism, originating from the ferromagnetic–antiferromagnetic competition. These results are helpful in the deeper understanding of phase transitions, band gap tunability, and magnetism variations in perovskite oxides and show the potential role, such materials can play, in perovskite solar cells and multiferroic applications.

  10. Anomalous optical switching and thermal hysteresis during semiconductor-metal phase transition of VO{sub 2} films on Si substrate

    SciTech Connect (OSTI)

    Leahu, G.; Li Voti, R., E-mail: roberto.livoti@uniroma1.it; Sibilia, C.; Bertolotti, M. [Dipartimento di Scienze di Base ed Applicate per l'Ingegneria, Sapienza Università di Roma, via A. Scarpa 16, 00161 Roma (Italy)] [Dipartimento di Scienze di Base ed Applicate per l'Ingegneria, Sapienza Università di Roma, via A. Scarpa 16, 00161 Roma (Italy)

    2013-12-02T23:59:59.000Z

    We present a detailed infrared study of the semiconductor-to-metal transition (SMT) in a vanadium dioxide (VO{sub 2}) film deposited on silicon wafer. The VO{sub 2} phase transition is studied in the mid-infrared region by analyzing the transmittance and the reflectance measurements, and the calculated emissivity. The reflectance has been measured in two configurations: from the side of the VO{sub 2} film and from that of Si wafer. The results show a strong asymmetry between the emissivity in the two configurations, and the fact that the emissivity dynamic range from the silicon side is twice as large than that from the VO{sub 2} side. The temperature behaviour of the emissivity during the SMT put into evidence the phenomenon of the anomalous absorption in VO{sub 2}, which has been explained by applying the Maxwell Garnett effective medium approximation theory.

  11. Theoretical study of influencing factors on the dispersion of bulk band-gap edges and the surface states in topological insulators Bi{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3}

    SciTech Connect (OSTI)

    Rusinov, I. P., E-mail: rusinovip@gmail.com; Nechaev, I. A. [Tomsk State University (Russian Federation); Chulkov, E. V. [Donostia International Physics Center (DIPC) (Spain)

    2013-06-15T23:59:59.000Z

    The dispersion of the band-gap edge states in bulk topological insulators Bi{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3} is considered within density functional theory. The dependences of this dispersion both on the approximation used for an exchange-correlation functional at fixed unit cell parameters and atomic positions and on these parameters and positions that are obtained upon structural relaxation performed using a certain approximated functional are analyzed. The relative position of the Dirac point of topologically protected surface states and the valence band maximum in the surface electronic structure of the topological insulators is discussed.

  12. Linker-Induced Anomalous Emission of Organic-Molecule Conjugated Metal-Oxide Nanoparticles

    SciTech Connect (OSTI)

    Turkowski, Volodymyr; Babu, Suresh; Le, Duy; Kumar, Amit; Haldar, Manas K.; Wagh, Anil V.; Hu, Zhongjian; Karakoti, Ajay S.; Gesquiere, Andre J.; Law, Benedict; Mallik, Sanku; Rahman, Talat S.; Leuenberger, Michael N.; Seal, Sudipta

    2012-06-26T23:59:59.000Z

    Semiconductor nanoparticles conjugated with organic- and dye-molecules to yield high efficiency visible photoluminescence (PL) hold great potential for many future technological applications. We show that folic acid (FA)-conjugated to nanosize TiO2 and CeO2 particles demonstrates a dramatic increase of photoemission intensity at wavelengths between 500 and 700 nm when derivatized using aminopropyl trimethoxysilane (APTMS) as spacer-linker molecules between the metal oxide and FA. Using density-functional theory (DFT) and time-dependent DFT calculations we demonstrate that the strong increase of the PL can be explained by electronic transitions between the titania surface oxygen vacancy (OV) states and the low-energy excited states of the FA/APTMS molecule anchored onto the surface oxygen bridge sites in close proximity to the OVs. We suggest this scenario to be a universal feature for a wide class of metal oxide nanoparticles, including nanoceria, possessing a similar band gap (3 eV) and with a large surface-vacancy-related density of electronic states. We demonstrate that the molecule-nanoparticle linker can play a crucial role in tuning the electronic and optical properties of nanosystems by bringing optically active parts of the molecule and of the surface close to each other.

  13. Isotopically controlled semiconductors

    E-Print Network [OSTI]

    Haller, Eugene E.

    2006-01-01T23:59:59.000Z

    16 Isotopically Controlled Semiconductors Eugene E. Hallerof isotopically engineered semiconductors; for outstandingisotopically controlled semiconductor crystals. This article

  14. High-temperature stable W/GaAs interface and application to metal--semiconductor field-effect transistors and digital circuits

    SciTech Connect (OSTI)

    Josefowicz, J.Y.; Rensch, D.B.

    1987-11-01T23:59:59.000Z

    The thermal stability of the physical, chemical, and electrical properties of W thin films sputter deposited on GaAs were investigated. A variety of characterization methods, including thin film stress analysis, Auger analysis, Rutherford backscattering spectrometry (RBS) analysis, and Schottky barrier measurements showed that the W/GaAs interface remains stable after high-temperature furnace annealing at 900 /sup 0/C for 15 min or rapid-lamp annealing at 1000 /sup 0/C for 11 s. Some refractory metal compounds were also investigated, including, WSi, WN/sub x/, and TaSi/sub x/. Pure W films produced the best Schottky diode characteristics. The average Schottky barrier height was 0.70 +- 0.009 V across a 2-in wafer after furnace annealing at 800 /sup 0/C/15 min. Pure W self-aligned gate (SAG) metal-semiconductor field-effect transistors (MESFET) and digital circuits were also fabricated. Transconductances as high as 300 mS/mm (L/sub g/ = 1.0 ..mu..m) were measured for enhancement mode SAG MESFET's. Circuits were fabricated with SAG MESFET enhancement-resistor mode logic using pure W gates, including ring oscillators, with gate delay as low as 25 ps and divide-by-eight circuits that functioned at a frequency >1 GHz.

  15. Predicted band structures of III-V semiconductors in wurtzite phase

    E-Print Network [OSTI]

    Amrit De; Craig E. Pryor

    2009-08-13T23:59:59.000Z

    While non-nitride III-V semiconductors typically have a zincblende structure, they may also form wurtzite crystals under pressure or when grown as nanowhiskers. This makes electronic structure calculation difficult since the band structures of wurtzite III-V semiconductors are poorly characterized. We have calculated the electronic band structure for nine III-V semiconductors in the wurtzite phase using transferable empirical pseudopotentials including spin-orbit coupling. We find that all the materials have direct gaps. Our results differ significantly from earlier {\\it ab initio} calculations, and where experimental results are available (InP, InAs and GaAs) our calculated band gaps are in good agreement. We tabulate energies, effective masses, and linear and cubic Dresselhaus zero-field spin-splitting coefficients for the zone-center states. The large zero-field spin-splitting coefficients we find may lead to new functionalities for designing devices that manipulate spin degrees of freedom.

  16. Study of microstructure and semiconductor to metallic conductivity transition in solid state sintered Li{sub 0.5}Mn{sub 0.5}Fe{sub 2}O{sub 4??} spinel ferrite

    SciTech Connect (OSTI)

    Bhowmik, R. N., E-mail: rnbhowmik.phy@pondiuni.edu.in; Vijayasri, G. [Department of Physics, Pondicherry University, R. Venkataraman Nagar, Kalapet, Puducherry-605 014 (India)

    2013-12-14T23:59:59.000Z

    Li{sub 0.5}Mn{sub 0.5}Fe{sub 2}O{sub 4} ferrite has been prepared by solid state sintering route. XRD pattern showed single phased cubic spinel structure. The samples exhibited typical character of plastoferrite with ring shaped surface microstructure. New feature observed in the present ferrite is the frequency activated conductivity transition from semiconductor to metallic state above 800?K. The increase of conductivity with frequency in the semiconducting regime follows Jonscher power law, while decrease of conductivity in metallic regime obeys Drude equation. The conductivity in semiconductor regime has been understood by hopping mechanism of localized charge carriers among the cations in B sites of cubic spinel structure. At higher temperatures, overlapping of electronic orbitals from neighbouring ions and free particle like motion of lighter Li{sup +} ions among interstitial lattices contributed metallic conductivity. The samples provided evidence of localized nature of the charge carriers at lower temperatures and increasing delocalized character with the increase of measurement temperature. From application point of view, such ferrites behave as semiconductor at low temperature and allow electromagnetic wave to pass through, but transform into a metallic reflector with negative dielectric constant at high temperature.

  17. Lattice mismatched compound semiconductors and devices on silicon

    E-Print Network [OSTI]

    Yang, Li, Ph. D. Massachusetts Institute of Technology

    2011-01-01T23:59:59.000Z

    III-V compound semiconductors, due to their superior electron mobility, are promising candidates for n-type metal-oxide-semiconductor field effect transistors (MOSFETs). However, the limited size of III-V substrates and ...

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

    SciTech Connect (OSTI)

    Schleife, A; Bechstedt, F

    2012-02-15T23:59:59.000Z

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

  19. Characterization of device parameters in high-temperature metal-oxide-semiconductor field-effect transistors in. beta. -SiC thin films

    SciTech Connect (OSTI)

    Palmour, J.W.; Kong, H.S.; Davis, R.F.

    1988-08-15T23:59:59.000Z

    Both inversion- and depletion-mode n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) have been fabricated on ..beta..-SiC thin films grown by chemical-vapor deposition. The inversion-mode devices were made on in situ doped (Al) p-type ..beta..-SiC(100) thin films grown on Si(100) substrates. The depletion-mode MOSFETs were made on n-type ..beta..-SiC(111) thin films grown on the Si(0001) face of a 6H ..cap alpha..-SiC substrates. Stable saturation and low subthreshold currents were achieved at drain-source voltages exceeding 5 and 25 V for the inversion-mode and depletion-mode devices, respectively. The transconductance increased with temperature up to 673 K for the short-gate-length devices, of either mode, and then decreased with further increases in temperature. It is proposed that the transconductances and threshold voltages for the inversion-mode devices are greatly affected by minority-carrier injection from the source. Stable transistor action was observed for both types of devices at temperatures up to 823 K, with the depletion-mode devices operating very well up to 923 K.

  20. Physical understanding of electron mobility in asymmetrically strained InGaAs-on-insulator metal-oxide-semiconductor field-effect transistors fabricated by lateral strain relaxation

    SciTech Connect (OSTI)

    Kim, SangHyeon, E-mail: dadembyora@mosfet.t.u-tokyo.ac.jp, E-mail: sh-kim@kist.re.kr; Yokoyama, Masafumi; Ikku, Yuki; Nakane, Ryosho; Takenaka, Mitsuru; Takagi, Shinichi [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Ichikawa, Osamu; Osada, Takenori; Hata, Masahiko [Sumitomo Chemical Co. Ltd., 6 Kitahara, Tsukuba, Ibaraki 300-3294 (Japan)

    2014-03-17T23:59:59.000Z

    In this paper, we fabricated asymmetrically tensile-strained In{sub 0.53}Ga{sub 0.47}As-on-insulator (-OI) metal-oxide-semiconductor field-effect transistors (MOSFETs) using a lateral strain relaxation technique. A stripe-like line structure, fabricated in biaxially strained In{sub 0.53}Ga{sub 0.47}As-OI can lead to the lateral strain relaxation and asymmetric strain configuration in In{sub 0.53}Ga{sub 0.47}As-OI with the channel width of 100?nm. We have found that the effective mobility (?{sub eff}) enhancement in In{sub 0.53}Ga{sub 0.47}As-OI MOSFETs with uniaxial-like asymmetric strain becomes smaller than that in In{sub 0.53}Ga{sub 0.47}As-OI MOSFETs with biaxial strain. We have clarified from a systematic analysis between the strain values and the ?{sub eff} characteristics that this mobility behavior can be understood by the change of the energy level of the conduction band minimum due to the lateral strain relaxation.

  1. A microstructural approach toward the effect of thickness on semiconductor-to-metal transition characteristics of VO{sub 2} epilayers

    SciTech Connect (OSTI)

    Molaei, R., E-mail: rmolaei@ncsu.edu; Wu, F.; Narayan, J. [Department of Materials Science and Engineering, North Carolina State University, EB-1, Raleigh, North Carolina 27695-7907 (United States); Bayati, R. [Intel Corporation, IMO-SC, SC2, Santa Clara, California 95054 (United States)

    2014-04-28T23:59:59.000Z

    We report the control of semiconductor to metal transition in VO{sub 2}(010) epilayers integrated with Si(100) substrates buffered with an NiO[111]/YSZ[100] intermediate layer. VO{sub 2} epitaxial thin films were grown at different thicknesses varying from 10 to 200?nm using pulsed laser deposition technique. An epitaxial relationship of VO{sub 2}(010)?NiO(111)? YSZ(001)?Si(001) and VO{sub 2}[100]?NiO[110]? YSZ[100]?Si[100] was established at room temperature. The crystallographic alignment across the VO{sub 2}/NiO interface changes to VO{sub 2}(100)?NiO(111) and VO{sub 2}[001]?NiO[110] at the temperature of growth giving rise to a misfit strain of about 33.5% and 3.0% along two orthogonal in-plane orientations. The transition temperature was observed to vary from about 353 to 341?K, the transition amplitude increased by about five orders of magnitude, and the hysteresis decreased to about 3?K, as the thickness of VO{sub 2} layers increased from about 10 to 200?nm. These observations were explained based on strain characteristics, overall defect content and grain boundaries, and phenomenological thermodynamic models.

  2. Positive bias temperature instability in p-type metal-oxide-semiconductor devices with HfSiON/SiO{sub 2} gate dielectrics

    SciTech Connect (OSTI)

    Samanta, Piyas, E-mail: piyas@vcfw.org [Department of Physics, Vidyasagar College for Women, 39 Sankar Ghosh Lane, Kolkata 700 006 (India); Huang, Heng-Sheng; Chen, Shuang-Yuan [Institute of Mechatronic Engineering, National Taipei University of Technology, No. 1, Sec. 3, Chung-Hsiao E. Rd., Taipei 106, Taiwan (China); Liu, Chuan-Hsi [Department of Mechatronic Technology, National Taiwan Normal University, No. 162, Sec. 1, He-Ping E. Rd., Taipei 106, Taiwan (China); Cheng, Li-Wei [Central R and D Division, United Microelectronics Corporation, No. 3, Li-Hsin Rd. II, Hsinchu 300, Taiwan (China)

    2014-02-21T23:59:59.000Z

    We present a detailed investigation on positive-bias temperature stress (PBTS) induced degradation of nitrided hafnium silicate (HfSiON)/SiO{sub 2} gate stack in n{sup +}-poly crystalline silicon (polySi) gate p-type metal-oxide-semiconductor (pMOS) devices. The measurement results indicate that gate dielectric degradation is a composite effect of electron trapping in as-fabricated as well as newly generated neutral traps, resulting a significant amount of stress-induced leakage current and generation of surface states at the Si/SiO{sub 2} interface. Although, a significant amount of interface states are created during PBTS, the threshold voltage (V{sub T}) instability of the HfSiON based pMOS devices is primarily caused by electron trapping and detrapping. It is also shown that PBTS creates both acceptor- and donor-like interface traps via different depassivation mechanisms of the Si{sub 3}???SiH bonds at the Si/SiO{sub 2} interface in pMOS devices. However, the number of donor-like interface traps ?N{sub it}{sup D} is significantly greater than that of acceptor-like interface traps ?N{sup A}{sub it}, resulting the PBTS induced net interface traps as donor-like.

  3. Thin film three-dimensional topological insulator metal-oxide-semiconductor field-effect-transistors: A candidate for sub-10?nm devices

    SciTech Connect (OSTI)

    Akhavan, N. D., E-mail: nima.dehdashti@uwa.edu.au; Jolley, G.; Umana-Membreno, G. A.; Antoszewski, J.; Faraone, L. [Department of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, WA 6009 (Australia)

    2014-08-28T23:59:59.000Z

    Three-dimensional (3D) topological insulators (TI) are a new state of quantum matter in which surface states reside in the bulk insulating energy bandgap and are protected by time-reversal symmetry. It is possible to create an energy bandgap as a consequence of the interaction between the conduction band and valence band surface states from the opposite surfaces of a TI thin film, and the width of the bandgap can be controlled by the thin film thickness. The formation of an energy bandgap raises the possibility of thin-film TI-based metal-oxide-semiconductor field-effect-transistors (MOSFETs). In this paper, we explore the performance of MOSFETs based on thin film 3D-TI structures by employing quantum ballistic transport simulations using the effective continuous Hamiltonian with fitting parameters extracted from ab-initio calculations. We demonstrate that thin film transistors based on a 3D-TI structure provide similar electrical characteristics compared to a Si-MOSFET for gate lengths down to 10?nm. Thus, such a device can be a potential candidate to replace Si-based MOSFETs in the sub-10?nm regime.

  4. Analysis of AlN/AlGaN/GaN metal-insulator-semiconductor structure by using capacitance-frequency-temperature mapping

    SciTech Connect (OSTI)

    Shih, Hong-An; Kudo, Masahiro; Suzuki, Toshi-kazu [Center for Nano Materials and Technology, Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan)

    2012-07-23T23:59:59.000Z

    AlN/AlGaN/GaN metal-insulator-semiconductor (MIS) structure is analyzed by using capacitance-frequency-temperature (C-f-T) mapping. Applying sputtering-deposited AlN, we attained AlN/AlGaN/GaN MIS heterostructure field-effect transistors with much suppressed gate leakage currents, but exhibiting frequency dispersion in C-V characteristics owing to high-density AlN/AlGaN interface states. In order to investigate the interface states deteriorating the device performance, we measured temperature-dependent frequency dispersion in the C-V characteristics. As a result, we obtained C-f-T mapping, whose analysis gives the activation energies of electron trapping, namely the interface state energy levels, for a wide range of the gate biases. This analysis method is auxiliary to the conventional conductance method, serving as a valuable tool for characterization of wide-bandgap devices with deep interface states. From the analysis, we can directly evaluate the gate-control efficiency of the devices.

  5. Low-frequency noise in AlN/AlGaN/GaN metal-insulator-semiconductor devices: A comparison with Schottky devices

    SciTech Connect (OSTI)

    Le, Son Phuong; Nguyen, Tuan Quy; Shih, Hong-An; Kudo, Masahiro; Suzuki, Toshi-kazu, E-mail: tosikazu@jaist.ac.jp [Center for Nano Materials and Technology, Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan)

    2014-08-07T23:59:59.000Z

    We have systematically investigated low-frequency noise (LFN) in AlN/AlGaN/GaN metal-insulator-semiconductor (MIS) devices, where the AlN gate insulator layer was sputtering-deposited on the AlGaN surface, in comparison with LFN in AlGaN/GaN Schottky devices. By measuring LFN in ungated two-terminal devices and heterojunction field-effect transistors (HFETs), we extracted LFN characteristics in the intrinsic gated region of the HFETs. Although there is a bias regime of the Schottky-HFETs in which LFN is dominated by the gate leakage current, LFN in the MIS-HFETs is always dominated by only the channel current. Analyzing the channel-current-dominated LFN, we obtained Hooge parameters ? for the gated region as a function of the sheet electron concentration n{sub s} under the gate. In a regime of small n{sub s}, both the MIS- and Schottky-HFETs exhibit ??n{sub s}{sup ?1}. On the other hand, in a middle n{sub s} regime of the MIS-HFETs, ? decreases rapidly like n{sub s}{sup ??} with ????2-3, which is not observed for the Schottky-HFETs. In addition, we observe strong increase in ??n{sub s}{sup 3} in a large n{sub s} regime for both the MIS- and Schottky-HFETs.

  6. INCREASED CELL EFFICIENCY IN InGaAs THIN FILM SOLAR CELLS WITH DIELECTRIC AND METAL BACK REFLECTORS

    E-Print Network [OSTI]

    Atwater, Harry

    INCREASED CELL EFFICIENCY IN InGaAs THIN FILM SOLAR CELLS WITH DIELECTRIC AND METAL BACK REFLECTORS solar cells enable very high photovoltaic efficiencies by virtue of employing different band gap materials in series- connected tandem cells to access the full solar spectrum. Researchers focused

  7. SEMICONDUCTOR DETECTORS - AN INTRODUCTION

    E-Print Network [OSTI]

    Goulding, F.S.

    2011-01-01T23:59:59.000Z

    infrinfc primely owned dtfiw. SEMICONDUCTOR DETECTORS - ANi) LBL-7282 I. History Semiconductor detectors appeared onof alpha particles by semiconductor diodes several years

  8. Isotopically controlled semiconductors

    E-Print Network [OSTI]

    Haller, E.E.

    2004-01-01T23:59:59.000Z

    and phonons in semiconductors,” J. Non-Cryst. Solids 141 (LVM) Spectroscopy of Semiconductors,” Mat. Res. Soc. Symp.Isotopically Engineered Semiconductors – New Media for the

  9. Isotopically controlled semiconductors

    E-Print Network [OSTI]

    Haller, Eugene E.

    2001-01-01T23:59:59.000Z

    Transmutation Doping of Semiconductor Materials, NationalTransmutation Doping of Semiconductor Materials, NationalProperties of Doped Semiconductors , Solid State Series,

  10. Semiconductor Nanowires: What's Next?

    E-Print Network [OSTI]

    Yang, Peidong

    2011-01-01T23:59:59.000Z

    Semiconductor nanowires, what’s next? Peidong Yang, Ruoxuelater research into semiconductor whiskers with nanoscalewere popularized as semiconductor nanowires in the following

  11. Energetics of Electron Transfer at the Nanocrystalline Titanium Dioxide Semiconductor/ Aqueous Solution Interface: pH Invariance of the Metal-Based Formal Potential of a

    E-Print Network [OSTI]

    Energetics of Electron Transfer at the Nanocrystalline Titanium Dioxide Semiconductor/ Aqueous,4-(CH2PO3)-2,2-bipyridine)3 10-, bound to a nanocrystalline titanium dioxide film shows energy (ECB) of the underlying semiconductor electrode in response to the same environmental

  12. Hydrogen local vibrational modes in semiconductors

    SciTech Connect (OSTI)

    McCluskey, M D [Univ. of California, Berkeley, CA (United States). Dept. of Physics

    1997-06-01T23:59:59.000Z

    Following, a review of experimental techniques, theory, and previous work, the results of local vibrational mode (LVM) spectroscopy on hydrogen-related complexes in several different semiconductors are discussed. Hydrogen is introduced either by annealing in a hydrogen ambient. exposure to a hydrogen plasma, or during growth. The hydrogen passivates donors and acceptors in semiconductors, forming neutral complexes. When deuterium is substituted for hydrogen. the frequency of the LVM decreases by approximately the square root of two. By varying the temperature and pressure of the samples, the microscopic structures of hydrogen-related complexes are determined. For group II acceptor-hydrogen complexes in GaAs, InP, and GaP, hydrogen binds to the host anion in a bond-centered orientation, along the [111] direction, adjacent to the acceptor. The temperature dependent shift of the LVMs are proportional to the lattice thermal energy U(T), a consequence of anharmonic coupling between the LVM and acoustical phonons. In the wide band gap semiconductor ZnSe, epilayers grown by metalorganic chemical vapor phase epitaxy (MOCVD) and doped with As form As-H complexes. The hydrogen assumes a bond-centered orientation, adjacent to a host Zn. In AlSb, the DX centers Se and Te are passivated by hydrogen. The second, third, and fourth harmonics of the wag modes are observed. Although the Se-D complex has only one stretch mode, the Se-H stretch mode splits into three peaks. The anomalous splitting is explained by a new interaction between the stretch LVM and multi-phonon modes of the lattice. As the temperature or pressure is varied, and anti-crossing is observed between LVM and phonon modes.

  13. Enhanced visible-light absorption of mesoporous TiO2 by co-doping with transition-metal/nitrogen ions

    SciTech Connect (OSTI)

    Mathis, John [Embry-Riddle Aeronautical University; Bi, Zhonghe [ORNL; Bridges, Craig A [ORNL; Kidder, Michelle [ORNL; Paranthaman, Mariappan Parans [ORNL

    2013-01-01T23:59:59.000Z

    Titanium (IV) oxide, TiO2, has been the object of intense scrutiny for energy applications. TiO2 is inexpensive, non-toxic, and has excellent corrosion resistance when exposed to electrolytes. A major drawback preventing the widespread use TiO2 for photolysis is its relatively large band gap of ~3eV. Only light with wavelengths shorter than 400 nm, which is in the ultraviolet portion of the spectrum, has sufficient energy to be absorbed. Less than 14 percent of the solar irradiation reaching the earth s surface has energy exceeding this band gap. Adding dopants such as transition metals has long been used to reduce the gap and increase photocatalytic activity by accessing the visible part of the solar spectrum. The degree to which the band gap is reduced using transition metals depends in part on the overlap of the d-orbitals of the transition metals with the oxygen p-orbitals. Therefore, doping with anions such as nitrogen to modify the cation-anion orbital overlap is another approach to reduce the gap. Recent studies suggest that using a combination of transition metals and nitrogen as dopants is more effective at introducing intermediate states within the band gap, effectively narrowing it. Here we report the synthesis of mesoporous TiO2 spheres, co-doped with transition metals and nitrogen that exhibit a nearly flat absorbance response across the visible spectrum extending into the near infrared.

  14. A methodology to identify and quantify mobility-reducing defects in 4H-silicon carbide power metal-oxide-semiconductor field-effect transistors

    SciTech Connect (OSTI)

    Ettisserry, D. P., E-mail: deva@umd.edu; Goldsman, N. [Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland 20742 (United States); Lelis, A. [U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783 (United States)

    2014-03-14T23:59:59.000Z

    In this paper, we present a methodology for the identification and quantification of defects responsible for low channel mobility in 4H-Silicon Carbide (SiC) power metal-oxide-semiconductor field-effect transistors (MOSFETs). To achieve this, we use an algorithm based on 2D-device simulations of a power MOSFET, density functional simulations, and measurement data. Using physical modeling of carrier mobility and interface traps, we reproduce the experimental I-V characteristics of a 4H-SiC doubly implanted MOSFET through drift-diffusion simulation. We extract the position of Fermi level and the occupied trap density as a function of applied bias and temperature. Using these inputs, our algorithm estimates the number of possible trap types, their energy levels, and concentrations at 4H-SiC/SiO{sub 2} interface. Subsequently, we use density functional theory (DFT)-based ab initio simulations to identify the atomic make-up of defects causing these trap levels. We study silicon vacancy and carbon di-interstitial defects in the SiC side of the interface. Our algorithm indicates that the D{sub it} spectrum near the conduction band edge (3.25?eV) is composed of three trap types located at 2.8–2.85?eV, 3.05?eV, and 3.1–3.2?eV, and also calculates their densities. Based on DFT simulations, this work attributes the trap levels very close to the conduction band edge to the C di-interstitial defect.

  15. Sample size requirements for estimating effective dose from computed tomography using solid-state metal-oxide-semiconductor field-effect transistor dosimetry

    SciTech Connect (OSTI)

    Trattner, Sigal [Department of Medicine, Division of Cardiology, Columbia University Medical Center and New York-Presbyterian Hospital, New York, New York 10032 (United States)] [Department of Medicine, Division of Cardiology, Columbia University Medical Center and New York-Presbyterian Hospital, New York, New York 10032 (United States); Cheng, Bin [Department of Biostatistics, Columbia University Mailman School of Public Health, New York, New York 10032 (United States)] [Department of Biostatistics, Columbia University Mailman School of Public Health, New York, New York 10032 (United States); Pieniazek, Radoslaw L. [Center for Radiological Research, Columbia University Medical Center and New York-Presbyterian Hospital, New York, New York 10032 (United States)] [Center for Radiological Research, Columbia University Medical Center and New York-Presbyterian Hospital, New York, New York 10032 (United States); Hoffmann, Udo [Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States)] [Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States); Douglas, Pamela S. [Department of Medicine, Division of Cardiology, Duke University, Durham, North Carolina 27715 (United States)] [Department of Medicine, Division of Cardiology, Duke University, Durham, North Carolina 27715 (United States); Einstein, Andrew J., E-mail: andrew.einstein@columbia.edu [Department of Medicine, Division of Cardiology, Columbia University Medical Center and New York-Presbyterian Hospital, New York, New York and Department of Radiology, Columbia University Medical Center and New York-Presbyterian Hospital, New York, New York (United States)

    2014-04-15T23:59:59.000Z

    Purpose: Effective dose (ED) is a widely used metric for comparing ionizing radiation burden between different imaging modalities, scanners, and scan protocols. In computed tomography (CT), ED can be estimated by performing scans on an anthropomorphic phantom in which metal-oxide-semiconductor field-effect transistor (MOSFET) solid-state dosimeters have been placed to enable organ dose measurements. Here a statistical framework is established to determine the sample size (number of scans) needed for estimating ED to a desired precision and confidence, for a particular scanner and scan protocol, subject to practical limitations. Methods: The statistical scheme involves solving equations which minimize the sample size required for estimating ED to desired precision and confidence. It is subject to a constrained variation of the estimated ED and solved using the Lagrange multiplier method. The scheme incorporates measurement variation introduced both by MOSFET calibration, and by variation in MOSFET readings between repeated CT scans. Sample size requirements are illustrated on cardiac, chest, and abdomen–pelvis CT scans performed on a 320-row scanner and chest CT performed on a 16-row scanner. Results: Sample sizes for estimating ED vary considerably between scanners and protocols. Sample size increases as the required precision or confidence is higher and also as the anticipated ED is lower. For example, for a helical chest protocol, for 95% confidence and 5% precision for the ED, 30 measurements are required on the 320-row scanner and 11 on the 16-row scanner when the anticipated ED is 4 mSv; these sample sizes are 5 and 2, respectively, when the anticipated ED is 10 mSv. Conclusions: Applying the suggested scheme, it was found that even at modest sample sizes, it is feasible to estimate ED with high precision and a high degree of confidence. As CT technology develops enabling ED to be lowered, more MOSFET measurements are needed to estimate ED with the same precision and confidence.

  16. Wafer-fused semiconductor radiation detector

    DOE Patents [OSTI]

    Lee, Edwin Y. (Livermore, CA); James, Ralph B. (Livermore, CA)

    2002-01-01T23:59:59.000Z

    Wafer-fused semiconductor radiation detector useful for gamma-ray and x-ray spectrometers and imaging systems. The detector is fabricated using wafer fusion to insert an electrically conductive grid, typically comprising a metal, between two solid semiconductor pieces, one having a cathode (negative electrode) and the other having an anode (positive electrode). The wafer fused semiconductor radiation detector functions like the commonly used Frisch grid radiation detector, in which an electrically conductive grid is inserted in high vacuum between the cathode and the anode. The wafer-fused semiconductor radiation detector can be fabricated using the same or two different semiconductor materials of different sizes and of the same or different thicknesses; and it may utilize a wide range of metals, or other electrically conducting materials, to form the grid, to optimize the detector performance, without being constrained by structural dissimilarity of the individual parts. The wafer-fused detector is basically formed, for example, by etching spaced grooves across one end of one of two pieces of semiconductor materials, partially filling the grooves with a selected electrical conductor which forms a grid electrode, and then fusing the grooved end of the one semiconductor piece to an end of the other semiconductor piece with a cathode and an anode being formed on opposite ends of the semiconductor pieces.

  17. Stable surface passivation process for compound semiconductors

    DOE Patents [OSTI]

    Ashby, Carol I. H. (Edgewood, NM)

    2001-01-01T23:59:59.000Z

    A passivation process for a previously sulfided, selenided or tellurated III-V compound semiconductor surface. The concentration of undesired mid-gap surface states on a compound semiconductor surface is reduced by the formation of a near-monolayer of metal-(sulfur and/or selenium and/or tellurium)-semiconductor that is effective for long term passivation of the underlying semiconductor surface. Starting with the III-V compound semiconductor surface, any oxidation present thereon is substantially removed and the surface is then treated with sulfur, selenium or tellurium to form a near-monolayer of chalcogen-semiconductor of the surface in an oxygen-free atmosphere. This chalcogenated surface is then contacted with a solution of a metal that will form a low solubility chalcogenide to form a near-monolayer of metal-chalcogen-semiconductor. The resulting passivating layer provides long term protection for the underlying surface at or above the level achieved by a freshly chalcogenated compound semiconductor surface in an oxygen free atmosphere.

  18. Semiconductor switch geometry with electric field shaping

    DOE Patents [OSTI]

    Booth, Rex (Livermore, CA); Pocha, Michael D. (Livermore, CA)

    1994-01-01T23:59:59.000Z

    An optoelectric switch is disclosed that utilizes a cylindrically shaped and contoured GaAs medium or other optically active semiconductor medium to couple two cylindrically shaped metal conductors with flat and flared termination points each having an ovoid prominence centrally extending there from. Coupling the truncated ovoid prominence of each conductor with the cylindrically shaped optically active semiconductor causes the semiconductor to cylindrically taper to a triple junction circular line at the base of each prominence where the metal conductor conjoins with the semiconductor and a third medium such as epoxy or air. Tapering the semiconductor at the triple junction inhibits carrier formation and injection at the triple junction and thereby enables greater current carrying capacity through and greater sensitivity of the bulk area of the optically active medium.

  19. Semiconductor switch geometry with electric field shaping

    DOE Patents [OSTI]

    Booth, R.; Pocha, M.D.

    1994-08-23T23:59:59.000Z

    An optoelectric switch is disclosed that utilizes a cylindrically shaped and contoured GaAs medium or other optically active semiconductor medium to couple two cylindrically shaped metal conductors with flat and flared termination points each having an ovoid prominence centrally extending there from. Coupling the truncated ovoid prominence of each conductor with the cylindrically shaped optically active semiconductor causes the semiconductor to cylindrically taper to a triple junction circular line at the base of each prominence where the metal conductor conjoins with the semiconductor and a third medium such as epoxy or air. Tapering the semiconductor at the triple junction inhibits carrier formation and injection at the triple junction and thereby enables greater current carrying capacity through and greater sensitivity of the bulk area of the optically active medium. 10 figs.

  20. On band gaps in photonic crystal fibers

    E-Print Network [OSTI]

    Shane Cooper; Ilia Kamotski; Valery Smyshlyaev

    2014-11-02T23:59:59.000Z

    We consider the Maxwell's system for a periodic array of dielectric `fibers' embedded into a `matrix', with respective electric permittivities $\\epsilon_0$ and $\\epsilon_1$, which serves as a model for cladding in photonic crystal fibers (PCF). The interest is in describing admissible and forbidden (gap) pairs $(\\omega,k)$ of frequencies $\\omega$ and propagation constants $k$ along the fibers, for a Bloch wave solution on the cross-section. We show that, for "pre-critical" values of $k(\\omega)$ i.e. those just below $\\omega (\\min\\{\\epsilon_0,\\epsilon_1\\}\\mu)^{1/2}$ (where $\\mu$ is the magnetic permeability assumed constant for simplicity), the coupling specific to the Maxwell's systems leads to a particular partially degenerating PDE system for the axial components of the electromagnetic field. Its asymptotic analysis allows to derive the limit spectral problem where the fields are constrained in one of the phases by Cauchy-Riemann type relations. We prove related spectral convergence. We finally give some examples, in particular of small size "arrow" fibers ($\\epsilon_0>\\epsilon_1$) where the existence of the gaps near appropriate "micro-resonances" is demonstrated by a further asymptotic analysis.

  1. Details in Semiconductors Gordon Conference, New London, NH, August 3-8, 2008

    SciTech Connect (OSTI)

    Shengbai Zhang and Nancy Ryan Gray

    2009-09-16T23:59:59.000Z

    Continuing its tradition of excellence, this Gordon Conference will focus on research at the forefront of the field of defects in homogeneous and structured semiconductors. The conference will have a strong emphasis on the control of defects during growth and processing, with an increases emphasis on nanostructures as compared to previous conferences. Electronic, magnetic, and optical properties of bulk, thin film, and nanoscale semiconductors will be discussed in detail. In contrast to many conferences, which tend to focus on specific semiconductors, this conference deals with defects in a broad range of bulk and nanoscale electronic materials. This approach has proved to be extremely fruitful for advancing fundamental understanding in emerging materials such as wide-band-gap semiconductors, doped nanoparticles, and organic semiconductors. Presentations of state-of-the-art theoretical methods will contribute to a fundamental understanding of atomic-scale phenomena. The program consists of about twenty invited talks, with plenty of discussion time, and a number of contributed poster sessions. Because of the large amount of discussion time, the conference provides an ideal forum for dealing with topics that are new and/or controversial.

  2. Life-cycle Assessment of Semiconductors

    E-Print Network [OSTI]

    Boyd, Sarah B.

    2009-01-01T23:59:59.000Z

    SemiconductorThe Semiconductor Industry: Size, Growth andSemiconductor Life-cycle Environmental Impacts . . . . . . .

  3. Method for forming metal contacts

    DOE Patents [OSTI]

    Reddington, Erik; Sutter, Thomas C; Bu, Lujia; Cannon, Alexandra; Habas, Susan E; Curtis, Calvin J; Miedaner, Alexander; Ginley, David S; Van Hest, Marinus Franciscus Antonius Maria

    2013-09-17T23:59:59.000Z

    Methods of forming metal contacts with metal inks in the manufacture of photovoltaic devices are disclosed. The metal inks are selectively deposited on semiconductor coatings by inkjet and aerosol apparatus. The composite is heated to selective temperatures where the metal inks burn through the coating to form an electrical contact with the semiconductor. Metal layers are then deposited on the electrical contacts by light induced or light assisted plating.

  4. Diminished Short Channel Effects in Nanoscale Double-Gate Silicon-on-Insulator MetalOxideSemiconductor Field-Effect-Transistors

    E-Print Network [OSTI]

    Kumar, M. Jagadesh

    ) and the back-gate oxide (tb) thickness is 2 nm. The doping in the p-type body and n+ source/drain regions­Oxide­Semiconductor Field-Effect-Transistors due to Induced Back-Gate Step Potential M. Jagadesh KUMAR Ã and G. Venkateshwar surface potential profile at the back gate of an asymmetrical double gate (DG) silicon-on-insulator (SOI

  5. Inorganic Chemistry Solutions to Semiconductor Nanocrystal Problems

    SciTech Connect (OSTI)

    Alvarado, Samuel R. [Ames Laboratory; Guo, Yijun [Ames Laboratory; Ruberu, T. Purnima A. [Ames Laboratory; Tavasoli, Elham [Ames Laboratory; Vela, Javier [Ames Laboratory

    2014-03-15T23:59:59.000Z

    The optoelectronic and chemical properties of semiconductor nanocrystals heavily depend on their composition, size, shape and internal structure, surface functionality, etc. Available strategies to alter these properties through traditional colloidal syntheses and ligand exchange methods place a premium on specific reaction conditions and surfactant combinations. In this invited review, we apply a molecular-level understanding of chemical precursor reactivity to reliably control the morphology, composition and intimate architecture (core/shell vs. alloyed) of semiconductor nanocrystals. We also describe our work aimed at achieving highly selective, low-temperature photochemical methods for the synthesis of semiconductor–metal and semiconductor–metal oxide photocatalytic nanocomposites. In addition, we describe our work on surface modification of semiconductor nanocrystal quantum dots using new approaches and methods that bypass ligand exchange, retaining the nanocrystal's native ligands and original optical properties, as well as on spectroscopic methods of characterization useful in determining surface ligand organization and chemistry. Using recent examples from our group and collaborators, we demonstrate how these efforts have lead to faster, wider and more systematic application of semiconductor nanocrystal-based materials to biological imaging and tracking, and to photocatalysis of unconventional substrates. We believe techniques and methods borrowed from inorganic chemistry (including coordination, organometallic and solid state chemistry) have much to offer in reaching a better understanding of the synthesis, functionalization and real-life application of such exciting materials as semiconductor nanocrystals (quantum dots, rods, tetrapods, etc.).

  6. Optical nano-woodpiles: large-area metallic photonic crystals and metamaterials

    E-Print Network [OSTI]

    Ibbotson, Lindsey A.; Demetriadou, Angela; Stephen, Croxall; Hess, Ortwin; Baumberg, Jeremy J.

    2015-02-09T23:59:59.000Z

    to be flexible and stretch-tuneable without issues of bowing or collapse4,17. They also benefit from a high refractive index contrast due to the metal wires which exhibit negative permittivity below the metal’s plasma frequency, widening the band gap20,21. Gold... .-H., Kim, Y.-S., Constant, K. & Ho, K.-M. Woodpile metallic photonic crystals fabricated by using soft lithography for tailored thermal emission. Adv. Mater. 19, 791–794 (2007). 8. Rinne, S. A., Garcia-Santamaria, F. & Braun, P. V. Embedded cavities...

  7. Effects of hole localization on limiting p-type conductivity in oxide and nitride semiconductors

    SciTech Connect (OSTI)

    Lyons, J. L.; Janotti, A.; Van de Walle, C. G. [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States)

    2014-01-07T23:59:59.000Z

    We examine how hole localization limits the effectiveness of substitutional acceptors in oxide and nitride semiconductors and explain why p-type doping of these materials has proven so difficult. Using hybrid density functional calculations, we find that anion-site substitutional impurities in AlN, GaN, InN, and ZnO lead to atomic-like states that localize on the impurity atom itself. Substitution with cation-site impurities, on the other hand, triggers the formation of polarons that become trapped on nearest-neighbor anions, generally leading to large ionization energies for these acceptors. Unlike shallow effective-mass acceptors, these two types of deep acceptors couple strongly with the lattice, significantly affecting the optical properties and severely limiting prospects for achieving p-type conductivity in these wide-band-gap materials.

  8. Fabricating metal-oxide-semiconductor field-effect transistors on a polyethylene terephthalate substrate by applying low-temperature layer transfer of a single-crystalline silicon layer by meniscus force

    SciTech Connect (OSTI)

    Sakaike, Kohei; Akazawa, Muneki; Nakamura, Shogo [Department of Semiconductor Electronics and Integration Science, Graduate School of Advanced Sciences of Matter, Hiroshima University, Kagamiyama 1-3-1, Higashihiroshima, Hiroshima 739-8530 (Japan)] [Department of Semiconductor Electronics and Integration Science, Graduate School of Advanced Sciences of Matter, Hiroshima University, Kagamiyama 1-3-1, Higashihiroshima, Hiroshima 739-8530 (Japan); Higashi, Seiichiro [Department of Semiconductor Electronics and Integration Science, Graduate School of Advanced Sciences of Matter, Hiroshima University, Kagamiyama 1-3-1, Higashihiroshima, Hiroshima 739-8530 (Japan) [Department of Semiconductor Electronics and Integration Science, Graduate School of Advanced Sciences of Matter, Hiroshima University, Kagamiyama 1-3-1, Higashihiroshima, Hiroshima 739-8530 (Japan); Research Institute for Nanodevice and Bio Systems, Hiroshima University, Kagamiyama 1-4-2, Higashihiroshima, Hiroshima 739-8527 (Japan)

    2013-12-02T23:59:59.000Z

    A low-temperature local-layer technique for transferring a single-crystalline silicon (c-Si) film by using a meniscus force was proposed, and an n-channel metal-oxide-semiconductor field-effect transistor (MOSFET) was fabricated on polyethylene terephthalate (PET) substrate. It was demonstrated that it is possible to transfer and form c-Si films in the required shape at the required position on PET substrates at extremely low temperatures by utilizing a meniscus force. The proposed technique for layer transfer was applied for fabricating high-performance c-Si MOSFETs on a PET substrate. The fabricated MOSFET showed a high on/off ratio of more than 10{sup 8} and a high field-effect mobility of 609 cm{sup 2} V{sup ?1} s{sup ?1}.

  9. (Data in thousand metric tons of silicon content unless otherwise noted) Domestic Production and Use: Estimated value of silicon metal and alloys (excluding semiconductor-grade silicon)

    E-Print Network [OSTI]

    metal: Brazil, 37%; South Africa, 25%; Canada, 14%; Norway, 6%; and other, 18%. Total: Brazil, 20%; China, 16%; South Africa, 13%; Canada, 12%; and other, 39%. Tariff: Item Number Normal Trade Relations energy costs. Demand for silicon metal comes primarily from the aluminum and chemical industries

  10. Graded core/shell semiconductor nanorods and nanorod barcodes

    DOE Patents [OSTI]

    Alivisatos, A. Paul; Scher, Erik C.; Manna, Liberato

    2013-03-26T23:59:59.000Z

    Graded core/shell semiconductor nanorods and shapped nanorods are disclosed comprising Group II-VI, Group III-V and Group IV semiconductors and methods of making the same. Also disclosed are nanorod barcodes using core/shell nanorods where the core is a semiconductor or metal material, and with or without a shell. Methods of labeling analytes using the nanorod barcodes are also disclosed.

  11. Graded core/shell semiconductor nanorods and nanorod barcodes

    DOE Patents [OSTI]

    Alivisatos, A. Paul (Oakland, CA); Scher, Erik C. (San Francisco, CA); Manna, Liberato (Lecce, IT)

    2010-12-14T23:59:59.000Z

    Graded core/shell semiconductor nanorods and shaped nanorods are disclosed comprising Group II-VI, Group III-V and Group IV semiconductors and methods of making the same. Also disclosed are nanorod barcodes using core/shell nanorods where the core is a semiconductor or metal material, and with or without a shell. Methods of labeling analytes using the nanorod barcodes are also disclosed.

  12. Hydrogen in semiconductors and insulators

    E-Print Network [OSTI]

    Van de Walle, Chris G.

    2007-01-01T23:59:59.000Z

    level in two different semiconductors, illustrating the06-01999R1 Hydrogen in semiconductors and insulators SpecialA. oxide materials; A. semiconductors; C. electronic

  13. Infrared spectroscopy of novel semiconductors /

    E-Print Network [OSTI]

    Chapler, Brian Caleb

    2014-01-01T23:59:59.000Z

    dilute magnetic semiconductor . . . . . . . . 1 1.1.1in the topological semiconductors Bi2Te3 and Mn—dopedM. Fundamentals of semiconductors. Springer-Verlag, Berlin,

  14. Novel room temperature ferromagnetic semiconductors

    E-Print Network [OSTI]

    Gupta, Amita

    2004-01-01T23:59:59.000Z

    Spin Related Phenomena in Semiconductors, (27-28 Jan 1997,FERROMAGNETIC SEMICONDUCTORS Amita Gupta Stockholm, Junedata are processed by semiconductor chips, and stored in the

  15. High-field electroluminescence in semiconductor tunnel junctions with a Mn-doped GaAs layer

    SciTech Connect (OSTI)

    Hai, Pham Nam [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-0033 (Japan); Yatsui, Takashi; Ohtsu, Motoichi; Tanaka, Masaaki [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Nanophotonics Research Center, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2014-09-21T23:59:59.000Z

    We investigated high-field electroluminescence (EL) in semiconductor tunnel junctions with a Mn-doped GaAs layer (here, referred to as GaAs:Mn). Besides the band-gap emission of GaAs, the EL spectra show visible light emissions with two peaks at 1.94?eV and 2.19?eV, which are caused by d-d transitions of the Mn atoms excited by hot electrons. The threshold voltages for band-gap and visible light EL in the tunnel junctions with a GaAs:Mn electrode are 1.3?V higher than those of GaAs:Mn excited by hot holes in reserve biased p{sup +}-n junctions, which is consistent with the hot carrier transport in the band profiles of these structures. Our EL results at room temperature show that the electron temperature in GaAs:Mn can be as high as ?700?K for a low input electrical power density of 0.4?W/cm{sup 2}, while the lattice temperature of the GaAs:Mn layer can be kept at 340?K.

  16. Rare-earth transition-metal intermetallics: Structure-bonding-property relationships

    SciTech Connect (OSTI)

    Han, M.K.

    2006-05-06T23:59:59.000Z

    The explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding property relationships. The work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe{sub 13-x}Si{sub x} system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn{sub 13}-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides Re{sub 2-x}Fe{sub 4}Si{sub 14-y} and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi{sub 2}: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb{sub 3}Zn{sub 3.6}Al{sub 7.4}: Partially ordered structure of Tb{sub 3}Zn{sub 3.6}Al{sub 7.4} compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn{sub 39}(Cr{sub x}Al{sub 1-x}){sub 81}: These layered structures are similar to icosahedral Mn-Al quasicrystalline compounds. Therefore, this compound may provide new insights into the formation, composition and structure of quasicrystalline materials.

  17. Rare-Earth Transition-Metal Intermetallics: Structure-bonding-Property Relationships

    SciTech Connect (OSTI)

    Mi-Kyung Han

    2006-05-01T23:59:59.000Z

    Our explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding-property relationships. Our work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe{sub 13-x}Si{sub x} system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn{sub 13}-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides RE{sub 2-x}Fe{sub 4}Si{sub 14-y} and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi{sub 2}: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb{sub 3}Zn{sub 3.6}Al{sub 7.4}: Partially ordered structure of Tb{sub 3}Zn{sub 3.6}Al{sub 7.4} compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn{sub 39}(Cr{sub x}Al{sub 1-x}){sub 81}: These layered structures are similar to icosahedral Mn-Al quasicrystalline compounds. Therefore, this compound may provide new insights into the formation, composition and structure of quasicrystalline materials.

  18. Impurity gettering in semiconductors

    DOE Patents [OSTI]

    Sopori, B.L.

    1995-06-20T23:59:59.000Z

    A process for impurity gettering in a semiconductor substrate or device such as a silicon substrate or device is disclosed. The process comprises hydrogenating the substrate or device at the back side thereof with sufficient intensity and for a time period sufficient to produce a damaged back side. Thereafter, the substrate or device is illuminated with electromagnetic radiation at an intensity and for a time period sufficient to cause the impurities to diffuse to the back side and alloy with a metal there present to form a contact and capture the impurities. The impurity gettering process also can function to simultaneously passivate defects within the substrate or device, with the defects likewise diffusing to the back side for simultaneous passivation. Simultaneously, substantially all hydrogen-induced damage on the back side of the substrate or device is likewise annihilated. Also taught is an alternate process comprising thermal treatment after hydrogenation of the substrate or device at a temperature of from about 500 C to about 700 C for a time period sufficient to cause the impurities to diffuse to the damaged back side thereof for subsequent capture by an alloying metal. 1 fig.

  19. Impurity gettering in semiconductors

    DOE Patents [OSTI]

    Sopori, Bhushan L. (Denver, CO)

    1995-01-01T23:59:59.000Z

    A process for impurity gettering in a semiconductor substrate or device such as a silicon substrate or device. The process comprises hydrogenating the substrate or device at the back side thereof with sufficient intensity and for a time period sufficient to produce a damaged back side. Thereafter, the substrate or device is illuminated with electromagnetic radiation at an intensity and for a time period sufficient to cause the impurities to diffuse to the back side and alloy with a metal there present to form a contact and capture the impurities. The impurity gettering process also can function to simultaneously passivate defects within the substrate or device, with the defects likewise diffusing to the back side for simultaneous passivation. Simultaneously, substantially all hydrogen-induced damage on the back side of the substrate or device is likewise annihilated. Also taught is an alternate process comprising thermal treatment after hydrogenation of the substrate or device at a temperature of from about 500.degree. C. to about 700.degree. C. for a time period sufficient to cause the impurities to diffuse to the damaged back side thereof for subsequent capture by an alloying metal.

  20. Mixed semiconductor nanocrystal compositions

    DOE Patents [OSTI]

    Maskaly, Garry R. (Los Alamos, NM); Schaller, Richard D. (Santa Fe, NM); Klimov, Victor I. (Los Alamos, NM)

    2011-02-15T23:59:59.000Z

    Composition comprising one or more energy donors and one or more energy acceptors, wherein energy is transferred from the energy donor to the energy acceptor and wherein: the energy acceptor is a colloidal nanocrystal having a lower band gap energy than the energy donor; the energy donor and the energy acceptor are separated by a distance of 40 nm or less; wherein the average peak absorption energy of the acceptor is at least 20 meV greater than the average peak emission energy of the energy donor; and wherein the ratio of the number of energy donors to the number of energy acceptors is from about 2:1 to about 1000:1.

  1. Abstract--The electrical properties of the PVD AlN have been investigated by means of metal-insulator-semiconductor

    E-Print Network [OSTI]

    Technische Universiteit Delft

    to reduce the self-heating in silicon-on-glass bipolar junction transistors [15]. These devicesAbstract--The electrical properties of the PVD AlN have been investigated by means of metal silicon. In this paper the electrical properties of the PVD AlN when deposited on silicon have been

  2. Preparation of III-V semiconductor nanocrystals

    DOE Patents [OSTI]

    Alivisatos, A.P.; Olshavsky, M.A.

    1996-04-09T23:59:59.000Z

    Nanometer-scale crystals of III-V semiconductors are disclosed. They are prepared by reacting a group III metal source with a group V anion source in a liquid phase at elevated temperature in the presence of a crystallite growth terminator such as pyridine or quinoline. 4 figs.

  3. Preparation of III-V semiconductor nanocrystals

    DOE Patents [OSTI]

    Alivisatos, A. Paul (Berkeley, CA); Olshavsky, Michael A. (Brunswick, OH)

    1996-01-01T23:59:59.000Z

    Nanometer-scale crystals of III-V semiconductors are disclosed, They are prepared by reacting a group III metal source with a group V anion source in a liquid phase at elevated temperature in the presence of a crystallite growth terminator such as pyridine or quinoline.

  4. Unitary lens semiconductor device

    DOE Patents [OSTI]

    Lear, Kevin L. (Albuquerque, NM)

    1997-01-01T23:59:59.000Z

    A unitary lens semiconductor device and method. The unitary lens semiconductor device is provided with at least one semiconductor layer having a composition varying in the growth direction for unitarily forming one or more lenses in the semiconductor layer. Unitary lens semiconductor devices may be formed as light-processing devices such as microlenses, and as light-active devices such as light-emitting diodes, photodetectors, resonant-cavity light-emitting diodes, vertical-cavity surface-emitting lasers, and resonant cavity photodetectors.

  5. Compositional dependence of the luminescence of In{sub 0.49}(Al{sub {ital y}}Ga{sub 1{minus}{ital y}}){sub 0.51}P alloys near the direct{endash}indirect band-gap crossover

    SciTech Connect (OSTI)

    Nelson, J.S.; Jones, E.D. [Semiconductor Materials and Device Sciences Department, 1113, MS-0601, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Semiconductor Materials and Device Sciences Department, 1113, MS-0601, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Myers, S.M.; Follstaedt, D.M. [Semiconductor Nanostructure Physics Department, 1112, MS-1414, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Semiconductor Nanostructure Physics Department, 1112, MS-1414, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Hjalmarson, H.P. [Compound Semiconductor Technology Department, 1322, MS-0603, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Compound Semiconductor Technology Department, 1322, MS-0603, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Schirber, J.E. [Solid State Sciences Department, 1100, MS-1437, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Solid State Sciences Department, 1100, MS-1437, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Schneider, R.P. [Semiconductor Materials Department, 1311, MS-0603, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Semiconductor Materials Department, 1311, MS-0603, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Fouquet, J.E.; Robbins, V.M.; Carey, K.W. [Hewlett Packard Laboratories, 3500 Deer Creek Road, Palo Alto, California 94303 (United States)] [Hewlett Packard Laboratories, 3500 Deer Creek Road, Palo Alto, California 94303 (United States)

    1996-06-01T23:59:59.000Z

    A number of complementary experimental characterization tools and theoretical band structure methods were used to determine unambiguously the band-edge luminescence as a function of Al concentration, and to place an upper limit on the short-wavelength emission of InAlGaP alloys lattice matched to GaAs. In particular, the direct-to-indirect band-gap crossing has been determined by analyzing a series of metalorganic vapor-phase-epitaxy-grown In{sub 0.49}(Al{sub {ital y}}Ga{sub 1{minus}{ital y}}){sub 0.51}P alloys lattice matched to GaAs with double-crystal x-ray analysis, Rutherford backscattering spectroscopy, pressure- and temperature-dependent photoluminescence, and transmission electron microscopy. The experimental measurements are compared to first-principles plane-wave pseudopotential band structure calculations for the ternary end points, InGaP and InAlP. The maximum room temperature direct band gap is found to be 2.24 eV, corresponding to an Al composition of {ital y}=0.52{plus_minus}0.02, in good agreement with the theoretical prediction of 0.58{plus_minus}0.05. {copyright} {ital 1996 The American Physical Society.}

  6. Mismatched semiconductor nanowires: growth and characterization

    E-Print Network [OSTI]

    Yim, Joanne Wing Lan

    2011-01-01T23:59:59.000Z

    SemiconductorFundamentals of Semiconductors: Physics and MaterialsDilute III-V Nitride Semiconductors and Material Systems (

  7. Role of the dielectric for the charging dynamics of the dielectric/barrier interface in AlGaN/GaN based metal-insulator-semiconductor structures under forward gate bias stress

    SciTech Connect (OSTI)

    Lagger, P., E-mail: peter.lagger@infineon.com [Infineon Technologies Austria AG, Siemensstraße 2, 9500 Villach (Austria); Institute of Solid State Electronics, Vienna University of Technology, Floragasse 7, 1040 Wien (Austria); Steinschifter, P.; Reiner, M.; Stadtmüller, M.; Denifl, G.; Ostermaier, C. [Infineon Technologies Austria AG, Siemensstraße 2, 9500 Villach (Austria); Naumann, A.; Müller, J.; Wilde, L.; Sundqvist, J. [Fraunhofer IPMS-CNT, Königsbrücker Straße 178, 01099 Dresden (Germany); Pogany, D. [Institute of Solid State Electronics, Vienna University of Technology, Floragasse 7, 1040 Wien (Austria)

    2014-07-21T23:59:59.000Z

    The high density of defect states at the dielectric/III-N interface in GaN based metal-insulator-semiconductor structures causes tremendous threshold voltage drifts, ?V{sub th}, under forward gate bias conditions. A comprehensive study on different dielectric materials, as well as varying dielectric thickness t{sub D} and barrier thickness t{sub B}, is performed using capacitance-voltage analysis. It is revealed that the density of trapped electrons, ?N{sub it}, scales with the dielectric capacitance under spill-over conditions, i.e., the accumulation of a second electron channel at the dielectric/AlGaN barrier interface. Hence, the density of trapped electrons is defined by the charging of the dielectric capacitance. The scaling behavior of ?N{sub it} is explained universally by the density of accumulated electrons at the dielectric/III-N interface under spill-over conditions. We conclude that the overall density of interface defects is higher than what can be electrically measured, due to limits set by dielectric breakdown. These findings have a significant impact on the correct interpretation of threshold voltage drift data and are of relevance for the development of normally off and normally on III-N/GaN high electron mobility transistors with gate insulation.

  8. Interconnected semiconductor devices

    DOE Patents [OSTI]

    Grimmer, Derrick P. (White Bear Lake, MN); Paulson, Kenneth R. (North St. Paul, MN); Gilbert, James R. (St. Paul, MN)

    1990-10-23T23:59:59.000Z

    Semiconductor layer and conductive layer formed on a flexible substrate, divided into individual devices and interconnected with one another in series by interconnection layers and penetrating terminals.

  9. Semiconductor bridge (SCB) detonator

    DOE Patents [OSTI]

    Bickes, R.W. Jr.; Grubelich, M.C.

    1999-01-19T23:59:59.000Z

    The present invention is a low-energy detonator for high-density secondary-explosive materials initiated by a semiconductor bridge (SCB) igniter that comprises a pair of electrically conductive lands connected by a semiconductor bridge. The semiconductor bridge is in operational or direct contact with the explosive material, whereby current flowing through the semiconductor bridge causes initiation of the explosive material. Header wires connected to the electrically-conductive lands and electrical feed-throughs of the header posts of explosive devices, are substantially coaxial to the direction of current flow through the SCB, i.e., substantially coaxial to the SCB length. 3 figs.

  10. Semiconductor bridge (SCB) detonator

    DOE Patents [OSTI]

    Bickes, Jr., Robert W. (Albuquerque, NM); Grubelich, Mark C. (Albuquerque, NM)

    1999-01-01T23:59:59.000Z

    The present invention is a low-energy detonator for high-density secondary-explosive materials initiated by a semiconductor bridge igniter that comprises a pair of electrically conductive lands connected by a semiconductor bridge. The semiconductor bridge is in operational or direct contact with the explosive material, whereby current flowing through the semiconductor bridge causes initiation of the explosive material. Header wires connected to the electrically-conductive lands and electrical feed-throughs of the header posts of explosive devices, are substantially coaxial to the direction of current flow through the SCB, i.e., substantially coaxial to the SCB length.

  11. Features of the band structure and conduction mechanisms in the n-HfNiSn semiconductor heavily doped with Ru

    SciTech Connect (OSTI)

    Romaka, V. A., E-mail: vromaka@polynet.lviv.ua [National Academy of Sciences of Ukraine, Pidstrygach Institute for Applied Problems in Mechanics and Mathematics (Ukraine); Rogl, P. [Universität Wien, Institut für Physikalische Chemie (Austria); Romaka, V. V. [National University Lvivska Politekhnika (Ukraine); Stadnyk, Yu. V. [Ivan Franko National University of Lviv (Ukraine); Korzh, R. O.; Krayovskyy, V. Ya. [National University Lvivska Politekhnika (Ukraine); Horyn, A. M. [Ivan Franko National University of Lviv (Ukraine)

    2014-12-15T23:59:59.000Z

    The crystal and electronic structure and energy and kinetic properties of the n-HfNiSn semiconductor heavily doped with a Ru acceptor impurity are investigated in the temperature and Ru concentration ranges T = 80–400 K and N{sub A}{sup Ru} ? 9.5 × 10{sup 19}?5.7 × 10{sup 20} cm{sup ?3} (x = 0–0.03), respectively. The mechanism of structural-defect generation is established, which changes the band gap and degree of compensation of the semiconductor and consists in the simultaneous concentration reduction and elimination of donor structural defects by means of the displacement of ?1% of Ni atoms from the Hf (4a) positions, the generation of acceptor structural defects upon the substitution of Ru atoms for Ni atoms in the 4c positions, and the generation of donor defects in the form of vacancies in the Sn (4b) positions. The calculated electronic structure of HfNi{sub 1?x}Ru{sub x}Sn is consistent with the experiment. The results obtained are discussed within the Shklovsky-Efros model for a heavily doped and compensated semiconductor.

  12. Chemical dynamics and bonding at gas/semiconductor and oxide/semiconductor interfaces

    E-Print Network [OSTI]

    Bishop, Sarah R.

    2010-01-01T23:59:59.000Z

    applied to alternative semiconductor materials to determinephase oxides and semiconductor surfaces. Both experimentalunderstanding of the oxide/semiconductor interface. The

  13. REVIEW ARTICLE Semiconductor quantum dot-sensitized

    E-Print Network [OSTI]

    Cao, Guozhong

    of low-cost and high-performance solar cells for sustainable energy sources to re- place fossil fuels has) fabrication methods of QDs, and 4) nanocrystalline photoelectrodes for solar cells. We also make suggestions band gap depending on the QD size, 2) a larger extinction coefficient, 3) higher stability toward water

  14. Conductive layer for biaxially oriented semiconductor film growth

    DOE Patents [OSTI]

    Findikoglu, Alp T. (Los Alamos, NM); Matias, Vladimir (Santa Fe, NM)

    2007-10-30T23:59:59.000Z

    A conductive layer for biaxially oriented semiconductor film growth and a thin film semiconductor structure such as, for example, a photodetector, a photovoltaic cell, or a light emitting diode (LED) that includes a crystallographically oriented semiconducting film disposed on the conductive layer. The thin film semiconductor structure includes: a substrate; a first electrode deposited on the substrate; and a semiconducting layer epitaxially deposited on the first electrode. The first electrode includes a template layer deposited on the substrate and a buffer layer epitaxially deposited on the template layer. The template layer includes a first metal nitride that is electrically conductive and has a rock salt crystal structure, and the buffer layer includes a second metal nitride that is electrically conductive. The semiconducting layer is epitaxially deposited on the buffer layer. A method of making such a thin film semiconductor structure is also described.

  15. Picosecond soft X-ray absorption measurement of the photo-inducedinsulator-to-metal transition in VO2.

    SciTech Connect (OSTI)

    Cavalleri, Andrea; Chong, Henry H.W.; Fourmaux, Sylvain; Glover,Thornton E.; Heimann, Phil A.; Kieffer, Jean Claude; Mun, B. Simon; Padmore, Howard A.; Schoenlein, Robert W.

    2004-02-01T23:59:59.000Z

    We directly measure the photoinduced insulator-to-metal transition in VO2 using time-resolved near-edge x-ray absorption. Picosecond pulses of synchrotron radiation are used to detect the redshift in the vanadium L3edge at 516 eV, which is associated with the transient collapse of the low-temperature band gap. We identify a two-component temporal response, corresponding to an ultrafast transformation over a 50 nm surface layer, followed by 40 m/s thermal growth of the metallic phase into the bulk.

  16. Semiconductor Engineers in a Global Economy

    E-Print Network [OSTI]

    Brown, Clair; Linden, Greg

    2007-01-01T23:59:59.000Z

    Technology: The Case of Semiconductors. Brookings Institute:Society, Space, and Semiconductors in The Restructuring Ofin the Global Semiconductor Industry. ” California

  17. Synthesis and Characterization of Mesoporous Semiconductors

    E-Print Network [OSTI]

    Kang, Chris Byung-hwa

    2012-01-01T23:59:59.000Z

    Brock, S. L. “Porous semiconductor chalcogenide aerogels. ”Nanostructured Semiconductor. ” J. Am. Chem. Soc. , 127,in mesostructured semiconductors based on the [SnSe 4 ]4-

  18. Semiconductor Nanowires and Nanotubes for Energy Conversion

    E-Print Network [OSTI]

    Fardy, Melissa Anne

    2010-01-01T23:59:59.000Z

    Thermoelectricity in semiconductor nanostructures. Science,splitting using semiconductor electrodes. InternationalChalcogenides, Monographs in Semiconductor Physics, ed. L.S.

  19. Method for manufacturing electrical contacts for a thin-film semiconductor device

    DOE Patents [OSTI]

    Carlson, David E. (Yardley, PA); Dickson, Charles R. (Pennington, NJ); D'Aiello, Robert V. (East Brunswick, NJ)

    1988-11-08T23:59:59.000Z

    A method of fabricating spaced-apart back contacts on a thin film of semiconductor material by forming strips of buffer material on top of the semiconductor material in locations corresponding to the desired dividing lines between back contacts, forming a film of metal substantially covering the semiconductor material and buffer strips, and scribing portions of the metal film overlying the buffer strips with a laser without contacting the underlying semiconductor material to separate the metal layer into a plurality of back contacts. The buffer material serves to protect the underlying semiconductor material from being damaged during the laser scribing. Back contacts and multi-cell photovoltaic modules incorporating such back contacts also are disclosed.

  20. Ferromagnetic semiconductors based upon AlGaP M. E. Overberg,a)

    E-Print Network [OSTI]

    Hebard, Arthur F.

    band-gap ternary InGaP, which is lattice matched to GaAs. An immediate application of the DMS, with its wide band-gap binary GaP, AlP and ternary InGaP, AlGaP, AlInP components, is used for devices

  1. Method of doping a semiconductor

    DOE Patents [OSTI]

    Yang, Chiang Y. (Miller Place, NY); Rapp, Robert A. (Columbus, OH)

    1983-01-01T23:59:59.000Z

    A method for doping semiconductor material. An interface is established between a solid electrolyte and a semiconductor to be doped. The electrolyte is chosen to be an ionic conductor of the selected impurity and the semiconductor material and electrolyte are jointly chosen so that any compound formed from the impurity and the semiconductor will have a free energy no lower than the electrolyte. A potential is then established across the interface so as to allow the impurity ions to diffuse into the semiconductor. In one embodiment the semiconductor and electrolyte may be heated so as to increase the diffusion coefficient.

  2. Internal Image Potential in Semiconductors - Effect on Scanning-Tunneling-Microscopy

    E-Print Network [OSTI]

    HUANG, ZH; WEIMER, M.; Allen, Roland E.

    1993-01-01T23:59:59.000Z

    The tunneling of electrons from a semiconductor surface to a metal tip, across a vacuum gap, is influenced by two image interactions: an attractive image potential in the vacuum region, which lowers the apparent tunneling barrier, and a repulsive...

  3. Multiband semiconductor compositions for photovoltaic devices

    DOE Patents [OSTI]

    Walukiewicz, Wladyslaw (Kensington, CA); Yu, Kin Man (Lafayette, CA); Wu, Junqiao (Belmont, MA)

    2012-03-06T23:59:59.000Z

    The highly mismatched alloy Zn.sub.1-yMn.sub.yO.sub.xTe.sub.1-x, 0.ltoreq.y<1 and 0band gap of the Zn.sub.1-yMn.sub.yTe host. With multiple band gaps that fall within the solar energy spectrum, Zn.sub.1-yMn.sub.yO.sub.xTe.sub.1-x is a material perfectly satisfying the conditions for single-junction photovoltaics with the potential for power conversion efficiencies surpassing 50%.

  4. Multiband semiconductor compositions for photovoltaic devices

    DOE Patents [OSTI]

    Walukiewicz, Wladyslaw; Yu, Kin Man; Wu, Junqiao

    2010-05-04T23:59:59.000Z

    The highly mismatched alloy Zn1-yMnyOxTe1-x, 0.ltoreq.y<1 and 0band gap of the Zn1-yMnyTe host. With multiple band gaps that fall within the solar energy spectrum, Zn1-yMnyOxTe1-x is a material perfectly satisfying the conditions for single-junction photovoltaics with the potential for power conversion efficiencies surpassing 50%.

  5. 2012 DEFECTS IN SEMICONDUCTORS GORDON RESEARCH CONFERENCE, AUGUST 12-17, 2012

    SciTech Connect (OSTI)

    GLASER, EVAN

    2012-08-17T23:59:59.000Z

    The meeting shall strive to develop and further the fundamental understanding of defects and their roles in the structural, electronic, optical, and magnetic properties of bulk, thin film, and nanoscale semiconductors and device structures. Point and extended defects will be addressed in a broad range of electronic materials of particular current interest, including wide bandgap semiconductors, metal-oxides, carbon-based semiconductors (e.g., diamond, graphene, etc.), organic semiconductors, photovoltaic/solar cell materials, and others of similar interest. This interest includes novel defect detection/imaging techniques and advanced defect computational methods.

  6. Structure and electronic properties features of amorphous chalhogenide semiconductor films prepared by ion-plasma spraying

    SciTech Connect (OSTI)

    Korobova, N., E-mail: korobova3@mail.ru; Timoshenkov, S. [Department of Microelectronics, National Research University of Electronic Technology (MIET), Zelenograd (Russian Federation); Almasov, N.; Prikhodko, O. [al-Farabi Kazakh National University, Almaty (Kazakhstan); Tsendin, K. [Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg (Russian Federation)

    2014-10-21T23:59:59.000Z

    Structure of amorphous chalcogenide semiconductor glassy As-S-Se films, obtained by high-frequency (HF) ion-plasma sputtering has been investigated. It was shown that the length of the atomic structure medium order and local structure were different from the films obtained by thermal vacuum evaporation. Temperature dependence of dark conductivity, as well as the dependence of the spectral transmittance has been studied. Conductivity value was determined at room temperature. Energy activation conductivity and films optical band gap have been calculated. Temperature and field dependence of the drift mobility of charge carriers in the HF As-S-Se films have been shown. Bipolarity of charge carriers drift mobility has been confirmed. Absence of deep traps for electrons in the As{sub 40}Se{sub 30}S{sub 30} spectrum of localized states for films obtained by HF plasma ion sputtering was determined. Bipolar drift of charge carriers was found in amorphous As{sub 40}Se{sub 30}S{sub 30} films obtained by ion-plasma sputtering of high-frequency, unlike the films of these materials obtained by thermal evaporation.

  7. Quantum Semiconductor Modeling Ansgar Jungel

    E-Print Network [OSTI]

    Jüngel, Ansgar

    Quantum Semiconductor Modeling Ansgar J¨ungel Vienna University of Technology, Austria www.jungel.at.vu Ansgar J¨ungel (TU Wien) Quantum Semiconductor Modeling www.jungel.at.vu 1 / 154 #12;Contents 1 Introduction 2 Semiconductor modeling 3 Microscopic quantum models Density matrices Schr¨odinger models Wigner

  8. Dielectric function of diluted magnetic semiconductors in the infrared regime

    E-Print Network [OSTI]

    Aguado, R.; Lopez-Sancho, MP; Sinova, Jairo; Brey, L.

    2004-01-01T23:59:59.000Z

    We present a study of the dielectric function of metallic (III,Mn)V diluted magnetic semiconductors in the infrared regime. Our theoretical approach is based on the kinetic exchange model for carrier induced (III,Mn)V ferromagnetism. The dielectric...

  9. Anodic Aluminum Oxide Templated Channel Electrodes via Atomic Layer A. B. F. Martinsona,b

    E-Print Network [OSTI]

    60439, USA Dye-sensitized solar cells (DSSCs) utilize high surface area metal oxide sintered particle aluminum oxide membranes via atomic layer deposition. Introduction Dye sensitized solar cells (DSSCs) These photoelectrochemical cells use molecular dyes to sensitize high area, wide band gap semiconductor oxide photoanodes

  10. Kansas Advanced Semiconductor Project

    SciTech Connect (OSTI)

    Baringer, P.; Bean, A.; Bolton, T.; Horton-Smith, G.; Maravin, Y.; Ratra, B.; Stanton, N.; von Toerne, E.; Wilson, G.

    2007-09-21T23:59:59.000Z

    KASP (Kansas Advanced Semiconductor Project) completed the new Layer 0 upgrade for D0, assumed key electronics projects for the US CMS project, finished important new physics measurements with the D0 experiment at Fermilab, made substantial contributions to detector studies for the proposed e+e- international linear collider (ILC), and advanced key initiatives in non-accelerator-based neutrino physics.

  11. A 250 GHz photonic band gap gyrotron amplifier

    E-Print Network [OSTI]

    Nanni, Emilio A. (Emilio Alessandro)

    2013-01-01T23:59:59.000Z

    This thesis reports the theoretical and experimental investigation of a novel gyrotron traveling-wave-tube (TWT) amplifier at 250 GHz. The gyrotron amplifier designed and tested in this thesis has achieved a peak small ...

  12. Experimental study of photonic band gap accelerator structures

    E-Print Network [OSTI]

    Marsh, Roark A

    2009-01-01T23:59:59.000Z

    This thesis reports theoretical and experimental research on a novel accelerator concept using a photonic bandgap (PBG) structure. Major advances in higher order mode (HOM) damping are required for the next generation of ...

  13. Correlation between surface chemistry, density and band gap in...

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

    of WO3 films. The XPS analyses indicate the formation of stoichiometric WO3 with tungsten existing in fully oxidized valence state (W6+). However, WO3 films grown at high...

  14. Band Gap Optimization of Two-Dimensional Photonic Crystals Using ...

    E-Print Network [OSTI]

    2009-07-10T23:59:59.000Z

    Jul 10, 2009 ... proven very important as device components for integrated optics ...... Inhibited spontaneous emission in solid-state physics and electronics.

  15. Substrate-Induced Band-Gap Opening in Epitaxial Graphene

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

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over Our InstagramStructure of All-Polymer. . ~0sFailureSubscribe Mark A.

  16. Substrate-Induced Band-Gap Opening in Epitaxial Graphene

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

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over Our InstagramStructure of All-Polymer. . ~0sFailureSubscribe Mark

  17. Substrate-Induced Band-Gap Opening in Epitaxial Graphene

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

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over Our InstagramStructure of All-Polymer. . ~0sFailureSubscribe MarkSubstrate-Induced

  18. Substrate-Induced Band-Gap Opening in Epitaxial Graphene

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

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over Our InstagramStructure of All-Polymer. . ~0sFailureSubscribe

  19. Substrate-Induced Band-Gap Opening in Epitaxial Graphene

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

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over Our InstagramStructure of All-Polymer. . ~0sFailureSubscribeSubstrate-Induced

  20. Method for Creating Photonic Band Gap Materials - Energy Innovation Portal

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

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHighand Retrievals from aRodMIT-HarvardEnergy Innovation Portal

  1. Substrate-Induced Band-Gap Opening in Epitaxial Graphene

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

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del SolStrengthening a solid ... StrengtheningLabSubmitting JobsSubseaSubstrate-Induced

  2. Charge transport mechanisms of graphene/semiconductor Schottky barriers: A theoretical and experimental study

    SciTech Connect (OSTI)

    Zhong, Haijian; Liu, Zhenghui; Xu, Gengzhao; Shi, Lin; Fan, Yingmin; Yang, Hui [Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); Xu, Ke, E-mail: kxu2006@sinano.ac.cn; Wang, Jianfeng; Ren, Guoqiang [Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); Suzhou Nanowin Science and Technology Co., Ltd., Suzhou 215123 (China)

    2014-01-07T23:59:59.000Z

    Graphene has been proposed as a material for semiconductor electronic and optoelectronic devices. Understanding the charge transport mechanisms of graphene/semiconductor Schottky barriers will be crucial for future applications. Here, we report a theoretical model to describe the transport mechanisms at the interface of graphene and semiconductors based on conventional semiconductor Schottky theory and a floating Fermi level of graphene. The contact barrier heights can be estimated through this model and be close to the values obtained from the experiments, which are lower than those of the metal/semiconductor contacts. A detailed analysis reveals that the barrier heights are as the function of the interface separations and dielectric constants, and are influenced by the interfacial states of semiconductors. Our calculations show how this behavior of lowering barrier heights arises from the Fermi level shift of graphene induced by the charge transfer owing to the unique linear electronic structure.

  3. Coated semiconductor devices for neutron detection

    DOE Patents [OSTI]

    Klann, Raymond T. (Bolingbrook, IL); McGregor, Douglas S. (Whitmore Lake, MI)

    2002-01-01T23:59:59.000Z

    A device for detecting neutrons includes a semi-insulated bulk semiconductor substrate having opposed polished surfaces. A blocking Schottky contact comprised of a series of metals such as Ti, Pt, Au, Ge, Pd, and Ni is formed on a first polished surface of the semiconductor substrate, while a low resistivity ("ohmic") contact comprised of metals such as Au, Ge, and Ni is formed on a second, opposed polished surface of the substrate. In one embodiment, n-type low resistivity pinout contacts comprised of an Au/Ge based eutectic alloy or multi-layered Pd/Ge/Ti/Au are also formed on the opposed polished surfaces and in contact with the Schottky and ohmic contacts. Disposed on the Schottky contact is a neutron reactive film, or coating, for detecting neutrons. The coating is comprised of a hydrogen rich polymer, such as a polyolefin or paraffin; lithium or lithium fluoride; or a heavy metal fissionable material. By varying the coating thickness and electrical settings, neutrons at specific energies can be detected. The coated neutron detector is capable of performing real-time neutron radiography in high gamma fields, digital fast neutron radiography, fissile material identification, and basic neutron detection particularly in high radiation fields.

  4. Synthesis and Characterization of Mesoporous Semiconductors and Their Energy Applications

    E-Print Network [OSTI]

    Kang, Chris Byung-hwa

    2013-01-01T23:59:59.000Z

    Biomaterials, Ceramics, and Semiconductors. ” Science, 277,I. “Nanostructured Semiconductors Templated by Cholesteryl-Nanostructured Semiconductor. ” J. Am. Chem. Soc. , 127,

  5. A Novel Class of High-TC Ferromagnetic Semiconductors

    E-Print Network [OSTI]

    Shlyk, L. V.

    2008-01-01T23:59:59.000Z

    Diluted magnetic semiconductor or clustering effect? ”,ferromagnetism in semiconductors”, J. Appl. Phys. , inMaking nonmagnetic semiconductors ferromagnetic”, Science,

  6. 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., E-mail: tarik-1006@mail.ru; Maistruk, E. V.; Maryanchuk, P. D. [Chernivtsy National University (Ukraine)

    2014-12-15T23:59:59.000Z

    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.

  7. Chemical nanofabrication: a general route to surface-patterned and free-standing transition metal chalcogenide nanostructures{

    E-Print Network [OSTI]

    Odom, Teri W.

    ; such properties are important for battery storage capacity.4 WS2 nanotubes exhibit a red shift in their band gap

  8. Semiconductor radiation detector

    DOE Patents [OSTI]

    Patt, Bradley E. (Sherman Oaks, CA); Iwanczyk, Jan S. (Los Angeles, CA); Tull, Carolyn R. (Orinda, CA); Vilkelis, Gintas (Westlake Village, CA)

    2002-01-01T23:59:59.000Z

    A semiconductor radiation detector is provided to detect x-ray and light photons. The entrance electrode is segmented by using variable doping concentrations. Further, the entrance electrode is physically segmented by inserting n+ regions between p+ regions. The p+ regions and the n+ regions are individually biased. The detector elements can be used in an array, and the p+ regions and the n+ regions can be biased by applying potential at a single point. The back side of the semiconductor radiation detector has an n+ anode for collecting created charges and a number of p+ cathodes. Biased n+ inserts can be placed between the p+ cathodes, and an internal resistor divider can be used to bias the n+ inserts as well as the p+ cathodes. A polysilicon spiral guard can be implemented surrounding the active area of the entrance electrode or surrounding an array of entrance electrodes.

  9. Low temperature production of large-grain polycrystalline semiconductors

    DOE Patents [OSTI]

    Naseem, Hameed A. (Fayetteville, AR); Albarghouti, Marwan (Loudonville, NY)

    2007-04-10T23:59:59.000Z

    An oxide or nitride layer is provided on an amorphous semiconductor layer prior to performing metal-induced crystallization of the semiconductor layer. The oxide or nitride layer facilitates conversion of the amorphous material into large grain polycrystalline material. Hence, a native silicon dioxide layer provided on hydrogenated amorphous silicon (a-Si:H), followed by deposited Al permits induced crystallization at temperatures far below the solid phase crystallization temperature of a-Si. Solar cells and thin film transistors can be prepared using this method.

  10. Semiconductor Ion Implanters

    SciTech Connect (OSTI)

    MacKinnon, Barry A. [Isys, 2727 Walsh Ave., Suite 103, Santa Clara, CA 95051 (United States); Ruffell, John P. [Group 3, LLC, Sunnyvale, CA 94086 (United States)

    2011-06-01T23:59:59.000Z

    In 1953 the Raytheon CK722 transistor was priced at $7.60. Based upon this, an Intel Xeon Quad Core processor containing 820,000,000 transistors should list at $6.2 billion. Particle accelerator technology plays an important part in the remarkable story of why that Intel product can be purchased today for a few hundred dollars. Most people of the mid twentieth century would be astonished at the ubiquity of semiconductors in the products we now buy and use every day. Though relatively expensive in the nineteen fifties they now exist in a wide range of items from high-end multicore microprocessors like the Intel product to disposable items containing 'only' hundreds or thousands like RFID chips and talking greeting cards. This historical development has been fueled by continuous advancement of the several individual technologies involved in the production of semiconductor devices including Ion Implantation and the charged particle beamlines at the heart of implant machines. In the course of its 40 year development, the worldwide implanter industry has reached annual sales levels around $2B, installed thousands of dedicated machines and directly employs thousands of workers. It represents in all these measures, as much and possibly more than any other industrial application of particle accelerator technology. This presentation discusses the history of implanter development. It touches on some of the people involved and on some of the developmental changes and challenges imposed as the requirements of the semiconductor industry evolved.

  11. WWW.MOTOROLA.COM/SEMICONDUCTORS Microcontrollers

    E-Print Network [OSTI]

    Song, Joe

    WWW.MOTOROLA.COM/SEMICONDUCTORS M68HC11 Microcontrollers M68HC11RM/D Rev. 6, 4/2002 M68HC11 Reference Manual FreescaleSemiconductor,I Freescale Semiconductor, Inc. For More Information On This Product, Go to: www.freescale.com nc... #12;FreescaleSemiconductor,I Freescale Semiconductor, Inc. For More

  12. Method of passivating semiconductor surfaces

    DOE Patents [OSTI]

    Wanlass, Mark W. (Golden, CO)

    1990-01-01T23:59:59.000Z

    A method of passivating Group III-V or II-VI semiconductor compound surfaces. The method includes selecting a passivating material having a lattice constant substantially mismatched to the lattice constant of the semiconductor compound. The passivating material is then grown as an ultrathin layer of passivating material on the surface of the Group III-V or II-VI semiconductor compound. The passivating material is grown to a thickness sufficient to maintain a coherent interface between the ultrathin passivating material and the semiconductor compound. In addition, a device formed from such method is also disclosed.

  13. Sandia National Laboratories: compound semiconductor

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

    compound semiconductor Sandia and EMCORE: Solar Photovoltaics, Fiber Optics, MODE, and Energy Efficiency On March 29, 2013, in Concentrating Solar Power, Energy, Partnership,...

  14. Method of passivating semiconductor surfaces

    DOE Patents [OSTI]

    Wanlass, M.W.

    1990-06-19T23:59:59.000Z

    A method is described for passivating Group III-V or II-VI semiconductor compound surfaces. The method includes selecting a passivating material having a lattice constant substantially mismatched to the lattice constant of the semiconductor compound. The passivating material is then grown as an ultrathin layer of passivating material on the surface of the Group III-V or II-VI semiconductor compound. The passivating material is grown to a thickness sufficient to maintain a coherent interface between the ultrathin passivating material and the semiconductor compound. In addition, a device formed from such method is also disclosed.

  15. Low frequency noise in GaN metal semiconductor and metal oxide semiconductor field effect transistors

    E-Print Network [OSTI]

    Pala, Nezih

    , and Systems Engineering and Center for Integrated Electronics and Electronics Manufacturing, CII 9017, University of South Carolina, Columbia, South Carolina 29208 Received 22 January 2001; accepted American Institute of Physics. DOI: 10.1063/1.1372364 I. INTRODUCTION A recent report on GaN highly doped

  16. Noise and synamics in semiconductor lasers

    E-Print Network [OSTI]

    Rana, Farhan, 1971-

    2003-01-01T23:59:59.000Z

    In this thesis, theoretical and experimental work on the noise and dynamics in continuous wave and mode-locked semiconductor lasers is presented. The main focus is on semiconductor cascade lasers and semiconductor mode-locked ...

  17. Semiconductors: From Manipulated to Managed Trade

    E-Print Network [OSTI]

    Tyson, Laura D'Andrea; Yoffie, David B.

    1991-01-01T23:59:59.000Z

    o f the Japanese semiconductor industry is a sucecsslul aridcommodnv product Ol the semiconductor industry. They are afor maJtini: semiconductors: »nc

  18. Electron vortices in semiconductors devicesa... Kamran Mohsenib

    E-Print Network [OSTI]

    Electron vortices in semiconductors devicesa... Kamran Mohsenib Aerospace Engineering Sciencies; published online 3 October 2005 The hydrodynamic model of electron transport in semiconductors is analyzed vorticity effects. Furthermore, conditions for observation of electron vortices in semiconductor devices

  19. Reactive codoping of GaAlInP compound semiconductors

    DOE Patents [OSTI]

    Hanna, Mark Cooper (Boulder, CO); Reedy, Robert (Golden, CO)

    2008-02-12T23:59:59.000Z

    A GaAlInP compound semiconductor and a method of producing a GaAlInP compound semiconductor are provided. The apparatus and method comprises a GaAs crystal substrate in a metal organic vapor deposition reactor. Al, Ga, In vapors are prepared by thermally decomposing organometallic compounds. P vapors are prepared by thermally decomposing phospine gas, group II vapors are prepared by thermally decomposing an organometallic group IIA or IIB compound. Group VIB vapors are prepared by thermally decomposing a gaseous compound of group VIB. The Al, Ga, In, P, group II, and group VIB vapors grow a GaAlInP crystal doped with group IIA or IIB and group VIB elements on the substrate wherein the group IIA or IIB and a group VIB vapors produced a codoped GaAlInP compound semiconductor with a group IIA or IIB element serving as a p-type dopant having low group II atomic diffusion.

  20. LCD, low-temperature soldering and compound semiconductor : the sources, market, applications and future prospects of indium in Malaysia

    E-Print Network [OSTI]

    Yong, Foo Nun

    2006-01-01T23:59:59.000Z

    Indium is a minor but very valuable metal. Decreasing supplies of indium from refining and increasing demands from LCD, low-temperature soldering and compound semiconductors have stimulated the indium price increase ...

  1. Metallization and insulization during impact

    SciTech Connect (OSTI)

    Gilman, J.J.

    1992-10-01T23:59:59.000Z

    It is pointed out that the large strains produced by hypervelocity impacts can be expected to produce dramatic changes in the chemical bonding (electronic structures) of materials. This will change the mechanical behavior towards increased ductility when a semiconductor is compressed until it becomes metallic; and towards increased brittleness when a transition metal is expanded so as to localize its d-band electrons. Both isotropic compression (expansion) and shear strains can cause these transformations. Critical deformation criteria are given based on the observed cubic to tetragonal transformations in compressed semiconductors.

  2. Climate VISION: Private Sector Initiatives: Semiconductors

    Office of Scientific and Technical Information (OSTI)

    Agreements The U.S. semiconductor industry, represented by the members of the Environmental Protection Agency's PFC ReductionClimate Partnership for the Semiconductor...

  3. Climate VISION: Private Sector Initiatives: Semiconductors: Resources...

    Office of Scientific and Technical Information (OSTI)

    over 100 companies that account for more than 83% of U.S.-based semiconductor production. The SIA provides a forum for domestic semiconductor companies to work collectively...

  4. Characterization of Amorphous Zinc Tin Oxide Semiconductors....

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

    Amorphous Zinc Tin Oxide Semiconductors. Characterization of Amorphous Zinc Tin Oxide Semiconductors. Abstract: Amorphous zinc tin oxide (ZTO) was investigated to determine the...

  5. Opportunities for Wide Bandgap Semiconductor Power Electronics...

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

    Opportunities for Wide Bandgap Semiconductor Power Electronics for Hydrogen and Fuel Cell Applications Opportunities for Wide Bandgap Semiconductor Power Electronics for Hydrogen...

  6. Layered semiconductor neutron detectors

    DOE Patents [OSTI]

    Mao, Samuel S; Perry, Dale L

    2013-12-10T23:59:59.000Z

    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  7. Variable temperature semiconductor film deposition

    DOE Patents [OSTI]

    Li, Xiaonan (Golden, CO); Sheldon, Peter (Lakewood, CO)

    1998-01-01T23:59:59.000Z

    A method of depositing a semiconductor material on a substrate. The method sequentially comprises (a) providing the semiconductor material in a depositable state such as a vapor for deposition on the substrate; (b) depositing the semiconductor material on the substrate while heating the substrate to a first temperature sufficient to cause the semiconductor material to form a first film layer having a first grain size; (c) continually depositing the semiconductor material on the substrate while cooling the substrate to a second temperature sufficient to cause the semiconductor material to form a second film layer deposited on the first film layer and having a second grain size smaller than the first grain size; and (d) raising the substrate temperature, while either continuing or not continuing to deposit semiconductor material to form a third film layer, to thereby anneal the film layers into a single layer having favorable efficiency characteristics in photovoltaic applications. A preferred semiconductor material is cadmium telluride deposited on a glass/tin oxide substrate already having thereon a film layer of cadmium sulfide.

  8. Variable temperature semiconductor film deposition

    DOE Patents [OSTI]

    Li, X.; Sheldon, P.

    1998-01-27T23:59:59.000Z

    A method of depositing a semiconductor material on a substrate is disclosed. The method sequentially comprises (a) providing the semiconductor material in a depositable state such as a vapor for deposition on the substrate; (b) depositing the semiconductor material on the substrate while heating the substrate to a first temperature sufficient to cause the semiconductor material to form a first film layer having a first grain size; (c) continually depositing the semiconductor material on the substrate while cooling the substrate to a second temperature sufficient to cause the semiconductor material to form a second film layer deposited on the first film layer and having a second grain size smaller than the first grain size; and (d) raising the substrate temperature, while either continuing or not continuing to deposit semiconductor material to form a third film layer, to thereby anneal the film layers into a single layer having favorable efficiency characteristics in photovoltaic applications. A preferred semiconductor material is cadmium telluride deposited on a glass/tin oxide substrate already having thereon a film layer of cadmium sulfide.

  9. Photoelectrochemistry in particulate systems. 7. Electron-transfer reactions of indium sulfide semiconductor colloids

    SciTech Connect (OSTI)

    Kamat, P.V.; Dimitrijevic, N.M.; Fessenden, R.W.

    1988-04-21T23:59:59.000Z

    Small semiconductor colloids of In/sub 2/S/sub 3/ have been prepared in aqueous and nonaqueous media and their absorption properties characterized. A transient photobleaching and formation of S/sup .-/ and S/sub 2/H/sub 2//sup .-/ radicals have been observed upon laser pulse (355 nm) excitation of these colloids. With the aid of transient absorption spectra, the anodic corrosion process in these semiconductor colloids has been elucidated by using laser flash photolysis and pulse radiolysis techniques. With the use of a zwitterionic viologen compound, the interfacial charge-transfer process at the semiconductor surface has been studied. The quantum yield for the reduction of zwitterionic viologen was 0.07, which is similar to the value obtained with other metal chalcogenide semiconductor colloids. The microenvironment of the stabilizer (Nafion) influenced the charge-transfer process between the semiconductor and the redox decay.

  10. Physics with isotopically controlled semiconductors

    SciTech Connect (OSTI)

    Haller, E. E., E-mail: eehaller@lbl.gov [University of California at Berkeley, Department of Materials Science and Engineering (United States)

    2010-07-15T23:59:59.000Z

    This paper is based on a tutorial presentation at the International Conference on Defects in Semiconductors (ICDS-25) held in Saint Petersburg, Russia in July 2009. The tutorial focused on a review of recent research involving isotopically controlled semiconductors. Studies with isotopically enriched semiconductor structures experienced a dramatic expansion at the end of the Cold War when significant quantities of enriched isotopes of elements forming semiconductors became available for worldwide collaborations. Isotopes of an element differ in nuclear mass, may have different nuclear spins and undergo different nuclear reactions. Among the latter, the capture of thermal neutrons which can lead to neutron transmutation doping, is the most prominent effect for semiconductors. Experimental and theoretical research exploiting the differences in all the properties has been conducted and will be illustrated with selected examples.

  11. Electrodeposited doped II-VI semiconductor films and devices incorporating such films

    SciTech Connect (OSTI)

    Ondris, M.; Picher, M.A.; Brownfield, R.E.

    1990-03-20T23:59:59.000Z

    This patent describes a photovoltaic device. It comprises: a first thin film of a compound semiconductor of a first conductivity type including tellurium and a metal selected from Group IIB of the Periodic Table of Elements and containing as a dopant impurity in a concentration not exceeding 10{sup 20} atoms per cubic centimeter a metal selected from Group IB, a second semiconductor thin film in contact with the first semiconductor thin film and having a second conductivity type opposite that of the first conductivity type and electrical contacts to each of the first and second semiconductor thin films. Also described is the device wherein the first thin film is p-type cadmium telluride.

  12. Scalable synthesis of layer-controlled WS{sub 2} and MoS{sub 2} sheets by sulfurization of thin metal films

    SciTech Connect (OSTI)

    Orofeo, Carlo M.; Suzuki, Satoru; Sekine, Yoshiaki; Hibino, Hiroki, E-mail: hibino.hiroki@lab.ntt.co.jp [NTT Basic Research Laboratories, NTT Corporation Atsugi, Kanagawa 243-0198 (Japan)

    2014-08-25T23:59:59.000Z

    Transition metal dichalcogenides (TMDs) have emerged as exciting 2D materials beyond graphene due to their promising applications in the field of electronics and optoelectronics. Hence, the ability to produce controllable and uniformly thick TMD sheets over a large area is of utmost important for large-scale applications. Here, a facile method of synthesizing large-area, layer-controlled WS{sub 2}, and MoS{sub 2} sheets by sulfurization of their corresponding thin metal films is reported. A metal film, which is deposited by magnetron sputtering method, can be adjusted to produce, with great control, the desired sheet thickness down to a monolayer. Various characterization techniques, such as Raman, photoluminescence, and transmission electron microscopy, were used to evaluate the grown films. The results confirmed some of the exotic properties of TMDs such as the thickness dependent band-gap transition (indirect to direct band gap) and Raman shift. Devices made directly on the as-grown film showed modest mobility, ranging from 0.005 to 0.01?cm{sup 2} V{sup ?1}s{sup ?1}. Our synthesis method is simple and could also be used to synthesize other TMDs.

  13. Semiconductor device PN junction fabrication using optical processing of amorphous semiconductor material

    DOE Patents [OSTI]

    Sopori, Bhushan; Rangappan, Anikara

    2014-11-25T23:59:59.000Z

    Systems and methods for semiconductor device PN junction fabrication are provided. In one embodiment, a method for fabricating an electrical device having a P-N junction comprises: depositing a layer of amorphous semiconductor material onto a crystalline semiconductor base, wherein the crystalline semiconductor base comprises a crystalline phase of a same semiconductor as the amorphous layer; and growing the layer of amorphous semiconductor material into a layer of crystalline semiconductor material that is epitaxially matched to the lattice structure of the crystalline semiconductor base by applying an optical energy that penetrates at least the amorphous semiconductor material.

  14. Semiconductor Bridge Cable Test

    SciTech Connect (OSTI)

    KING, TONY L.

    2002-01-01T23:59:59.000Z

    The semiconductor bridge (SCB) is an electroexplosive device used to initiate detonators. A C cable is commonly used to connect the SCB to a firing set. A series of tests were performed to identify smaller, lighter cables for firing single and multiple SCBs. This report provides a description of these tests and their results. It was demonstrated that lower threshold voltages and faster firing times can be achieved by increasing the wire size, which reduces ohmic losses. The RF 100 appears to be a reasonable substitute for C cable when firing single SCBs. This would reduce the cable volume by 68% and the weight by 67% while increasing the threshold voltage by only 22%. In general, RG 58 outperforms twisted pair when firing multiple SCBs in parallel. The RG 58's superior performance is attributed to its larger conductor size.

  15. Electrochemical lithiation and delithiation for control of magnetic properties of nanoscale transition metal oxides

    E-Print Network [OSTI]

    Sivakumar, Vikram

    2008-01-01T23:59:59.000Z

    Transition metal oxides comprise a fascinating class of materials displaying a variety of magnetic and electronic properties, ranging from half-metallic ferromagnets like CrO2, ferrimagnetic semiconductors like Fey's, and ...

  16. A new family of metal chalogenide thin film electrodes for photoelectrochemical applications

    SciTech Connect (OSTI)

    Rajeshwar, K.; Tacconi, N.R. de [Univ. of Texas, Arlington, TX (United States)

    1996-10-01T23:59:59.000Z

    A new family of metal/semiconductor electrocomposite photoelectrodes is described for photoelectrochemical (PEC) applications. These electrocomposites are prepared from an aqueous dispersion containing the targeted metal (in ionic form) and the semiconductor particles. Electrodeposition of the metal affords a matrix in which the semiconductor particles are occluded. This approach is illustrated for nickel/TiO{sub 2} and nickel/CdS model candidates. The influence of preparation variables (deposition potential, temperature, pH, semiconductor content) on the PEC behavior is described.

  17. Microbially-mediated method for synthesis of non-oxide semiconductor nanoparticles

    DOE Patents [OSTI]

    Phelps, Tommy J.; Lauf, Robert J.; Moon, Ji Won; Rondinone, Adam J.; Love, Lonnie J.; Duty, Chad Edward; Madden, Andrew Stephen; Li, Yiliang; Ivanov, Ilia N.; Rawn, Claudia Jeanette

    2014-06-24T23:59:59.000Z

    The invention is directed to a method for producing non-oxide semiconductor nanoparticles, the method comprising: (a) subjecting a combination of reaction components to conditions conducive to microbially-mediated formation of non-oxide semiconductor nanoparticles, wherein said combination of reaction components comprises i) anaerobic microbes, ii) a culture medium suitable for sustaining said anaerobic microbes, iii) a metal component comprising at least one type of metal ion, iv) a non-metal component containing at least one non-metal selected from the group consisting of S, Se, Te, and As, and v) one or more electron donors that provide donatable electrons to said anaerobic microbes during consumption of the electron donor by said anaerobic microbes; and (b) isolating said non-oxide semiconductor nanoparticles, which contain at least one of said metal ions and at least one of said non-metals. The invention is also directed to non-oxide semiconductor nanoparticle compositions produced as above and having distinctive properties.

  18. Mathematical Modeling of Semiconductor Devices

    E-Print Network [OSTI]

    Jüngel, Ansgar

    fibers. · Optoelectronic emitters convert an electronic signal into light. Examples are light-emitting diodes (LED) used in displays and indication lambs and semiconductor lasers used in compact disk systems

  19. Modeling the semiconductor industry dynamics

    E-Print Network [OSTI]

    Wu, Kailiang

    2008-01-01T23:59:59.000Z

    The semiconductor industry is an exciting and challenging industry. Strong demand at the application end, plus the high capital intensity and rapid technological innovation in manufacturing, makes it difficult to manage ...

  20. Universal alignment of hydrogen levels in semiconductors and insulators

    E-Print Network [OSTI]

    Van de Walle, C G

    2006-01-01T23:59:59.000Z

    including nitride semiconductors and transparent oxides.and C. G. Van de Walle, in Hydrogen in SemiconductorsII, Semiconductors and Semimetals Vol. 61, edited by N. H.

  1. Identifying semiconductors by d.c. ionization conductivity

    E-Print Network [OSTI]

    2006-01-01T23:59:59.000Z

    expected from high-Z semiconductor detectors? ,” IEEE Transand binary compound semiconductors and insulators,” J PhysIdentifying Semiconductors by D.C. Ionization Conductivity

  2. Nitride semiconductor Surface and interface characterization and device design

    E-Print Network [OSTI]

    Zhang, Hongtao

    2006-01-01T23:59:59.000Z

    Lett. 80 , D. Schroder, Semiconductor Material and Devicein III-V Nitride Semiconductors: Applications and Devices ,SAN DIEGO Nitride Semiconductor Surface and Interface

  3. Semiconductor Quantum Rods as Single Molecule Fluorescent Biological Labels

    E-Print Network [OSTI]

    2006-01-01T23:59:59.000Z

    Alivisatos, A.P. Semiconductor nanocrystas for biologicalemission from colloidal semiconductor quantum rods. ScienceLight amplification in semiconductor nanocrystals: Quantum

  4. Isovalent Anion Substitution in Ga-Mn-pnictide Ferromagnetic Semiconductors

    E-Print Network [OSTI]

    Stone, Peter

    2010-01-01T23:59:59.000Z

    63. O. Madelung, Semiconductors - Basic Data, 2nd Ed. (in Laser Annealing of Semiconductors, edited by J. M. PoateProperties of Semiconductors ("Atom" Publ. House, Moscow,

  5. Thin-film solar cell fabricated on a flexible metallic substrate

    DOE Patents [OSTI]

    Tuttle, John R.; Noufi, Rommel; Hasoon, Falah S.

    2006-05-30T23:59:59.000Z

    A thin-film solar cell (10) is provided. The thin-film solar cell (10) comprises a flexible metallic substrate (12) having a first surface and a second surface. A back metal contact layer (16) is deposited on the first surface of the flexible metallic substrate (12). A semiconductor absorber layer (14) is deposited on the back metal contact. A photoactive film deposited on the semiconductor absorber layer (14) forms a heterojunction structure and a grid contact (24) deposited on the heterjunction structure. The flexible metal substrate (12) can be constructed of either aluminium or stainless steel. Furthermore, a method of constructing a solar cell is provided. The method comprises providing an aluminum substrate (12), depositing a semiconductor absorber layer (14) on the aluminum substrate (12), and insulating the aluminum substrate (12) from the semiconductor absorber layer (14) to inhibit reaction between the aluminum substrate (12) and the semiconductor absorber layer (14).

  6. Thin-Film Solar Cell Fabricated on a Flexible Metallic Substrate

    DOE Patents [OSTI]

    Tuttle, J. R.; Noufi, R.; Hasoon, F. S.

    2006-05-30T23:59:59.000Z

    A thin-film solar cell (10) is provided. The thin-film solar cell (10) comprises a flexible metallic substrate (12) having a first surface and a second surface. A back metal contact layer (16) is deposited on the first surface of the flexible metallic substrate (12). A semiconductor absorber layer (14) is deposited on the back metal contact. A photoactive film deposited on the semiconductor absorber layer (14) forms a heterojunction structure and a grid contact (24) deposited on the heterjunction structure. The flexible metal substrate (12) can be constructed of either aluminium or stainless steel. Furthermore, a method of constructing a solar cell is provided. The method comprises providing an aluminum substrate (12), depositing a semiconductor absorber layer (14) on the aluminum substrate (12), and insulating the aluminum substrate (12) from the semiconductor absorber layer (14) to inhibit reaction between the aluminum substrate (12) and the semiconductor absorber layer (14).

  7. Internal gettering by metal alloy clusters

    DOE Patents [OSTI]

    Buonassisi, Anthony (San Diego, CA); Heuer, Matthias (Berkeley, CA); Istratov, Andrei A. (Albany, CA); Pickett, Matthew D. (Berkeley, CA); Marcus, Mathew A. (Berkeley, CA); Weber, Eicke R. (Piedmont, CA)

    2010-07-27T23:59:59.000Z

    The present invention relates to the internal gettering of impurities in semiconductors by metal alloy clusters. In particular, intermetallic clusters are formed within silicon, such clusters containing two or more transition metal species. Such clusters have melting temperatures below that of the host material and are shown to be particularly effective in gettering impurities within the silicon and collecting them into isolated, less harmful locations. Novel compositions for some of the metal alloy clusters are also described.

  8. Enhancement of band-to-band tunneling in mono-layer transition metal dichalcogenides two-dimensional materials by vacancy defects

    SciTech Connect (OSTI)

    Jiang, Xiang-Wei; Li, Shu-Shen [State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Gong, Jian [School of Physics Science and Technology, Inner Mongolia University, Hohhot 010021 (China); Xu, Nuo [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720 (United States); Zhang, Jinfeng; Hao, Yue [Key Laboratory of Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071 (China); Wang, Lin-Wang, E-mail: lwwang@lbl.gov [Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2014-01-13T23:59:59.000Z

    The band-to-band tunneling of monolayer transition metal dichalcogenides nano-junction is investigated using atomistic ab initio quantum transport simulations. From the simulation, it is found that the transition metal vacancy defect in the two-dimensional MX{sub 2} (M = Mo,W; X = S,Se) band-to-band tunneling diode can dramatically boost the on-state current up to 10 times while maintaining the device sub-threshold swing. The performance enhancement mechanism is discussed in detail by examining partial density of states of the system. It is found that the transition metal vacancy induces band-gap states, which reduce the effective length of the tunneling transition region.

  9. Theory of Organic Magnetoresistance in Disordered Organic Semiconductors

    E-Print Network [OSTI]

    Flatte, Michael E.

    Theory of Organic Magnetoresistance in Disordered Organic Semiconductors Nicholas J. Harmon semiconductors, disordered semiconductors, organic magnetoresistance, percolation theory, spin transport organic semiconductors. The theory proposed here maps the complex phenomena of spin-dependent hopping onto

  10. ECE 344--Semiconductor Devices & Materials ECE Department, UMass Amherst

    E-Print Network [OSTI]

    Massachusetts at Amherst, University of

    1 Syllabus ECE 344--Semiconductor Devices & Materials ECE Department, UMass Amherst Fall 2013 transport in semiconductors Explain the operating principles in semiconductor devices (diodes, capacitors Topics: Fundamentals of Semiconductors; Theory of Electrical Conduction; Device Operations (See "Class

  11. ECE 609 Semiconductor Devices Department of Electrical and Computer Engineering

    E-Print Network [OSTI]

    Massachusetts at Amherst, University of

    ECE 609 ­ Semiconductor Devices Department of Electrical and Computer Engineering University of semiconductor electronic devices in terms of material properties, interface and junction characteristics). ________________________________________________________________________ Preliminary Course Outline 1. Overview of Semiconductor Physics 1.1 Semiconductor Materials

  12. Wide-Bandgap Semiconductors

    SciTech Connect (OSTI)

    Chinthavali, M.S.

    2005-11-22T23:59:59.000Z

    With the increase in demand for more efficient, higher-power, and higher-temperature operation of power converters, design engineers face the challenge of increasing the efficiency and power density of converters [1, 2]. Development in power semiconductors is vital for achieving the design goals set by the industry. Silicon (Si) power devices have reached their theoretical limits in terms of higher-temperature and higher-power operation by virtue of the physical properties of the material. To overcome these limitations, research has focused on wide-bandgap materials such as silicon carbide (SiC), gallium nitride (GaN), and diamond because of their superior material advantages such as large bandgap, high thermal conductivity, and high critical breakdown field strength. Diamond is the ultimate material for power devices because of its greater than tenfold improvement in electrical properties compared with silicon; however, it is more suited for higher-voltage (grid level) higher-power applications based on the intrinsic properties of the material [3]. GaN and SiC power devices have similar performance improvements over Si power devices. GaN performs only slightly better than SiC. Both SiC and GaN have processing issues that need to be resolved before they can seriously challenge Si power devices; however, SiC is at a more technically advanced stage than GaN. SiC is considered to be the best transition material for future power devices before high-power diamond device technology matures. Since SiC power devices have lower losses than Si devices, SiC-based power converters are more efficient. With the high-temperature operation capability of SiC, thermal management requirements are reduced; therefore, a smaller heat sink would be sufficient. In addition, since SiC power devices can be switched at higher frequencies, smaller passive components are required in power converters. Smaller heat sinks and passive components result in higher-power-density power converters. With the advent of the use of SiC devices it is imperative that models of these be made available in commercial simulators. This enables power electronic designers to simulate their designs for various test conditions prior to fabrication. To build an accurate transistor-level model of a power electronic system such as an inverter, the first step is to characterize the semiconductor devices that are present in the system. Suitable test beds need to be built for each device to precisely test the devices and obtain relevant data that can be used for modeling. This includes careful characterization of the parasitic elements so as to emulate the test setup as closely as possible in simulations. This report is arranged as follows: Chapter 2--The testing and characterization of several diodes and power switches is presented. Chapter 3--A 55-kW hybrid inverter (Si insulated gate bipolar transistor--SiC Schottky diodes) device models and test results are presented. A detailed description of the various test setups followed by the parameter extraction, modeling, and simulation study of the inverter performance is presented. Chapter 4--A 7.5-kW all-SiC inverter (SiC junction field effect transistors (JFET)--SiC Schottky diodes) was built and tested. The models built in Saber were validated using the test data and the models were used in system applications in the Saber simulator. The simulation results and a comparison of the data from the prototype tests are discussed in this chapter. Chapter 5--The duration test results of devices utilized in buck converters undergoing reliability testing are presented.

  13. Searching Room Temperature Ferromagnetism in Wide Gap Semiconductors Fe-doped Strontium Titanate and Zinc Oxide

    E-Print Network [OSTI]

    Pereira, LMC; Wahl, U

    Scientic findings in the very beginning of the millennium are taking us a step further in the new paradigm of technology: spintronics. Upgrading charge-based electronics with the additional degree of freedom of the carriers spin-state, spintronics opens a path to the birth of a new generation of devices with the potential advantages of non-volatility and higher processing speed, integration densities and power efficiency. A decisive step towards this new age lies on the attribution of magnetic properties to semiconductors, the building block of today's electronics, that is, the realization of ferromagnetic semiconductors (FS) with critical temperatures above room temperature. Unfruitful search for intrinsic RT FS lead to the concept of Dilute(d) Magnetic Semiconductors (DMS): ordinary semiconductor materials where 3 d transition metals randomly substitute a few percent of the matrix cations and, by some long-range mechanism, order ferromagnetically. The times are of intense research activity and the last few ...

  14. Correlated exciton dynamics in semiconductor nanostructures

    E-Print Network [OSTI]

    Wen, Patrick, Ph. D. Massachusetts Institute of Technology

    2013-01-01T23:59:59.000Z

    The absorption and dissipation of energy in semiconductor nanostructures are often determined by excited electron dynamics. In semiconductors, one fundamentally important electronic state is an exciton, an excited electron ...

  15. Method of preparing nitrogen containing semiconductor material

    DOE Patents [OSTI]

    Barber, Greg D.; Kurtz, Sarah R.

    2004-09-07T23:59:59.000Z

    A method of combining group III elements with group V elements that incorporates at least nitrogen from a nitrogen halide for use in semiconductors and in particular semiconductors in photovoltaic cells.

  16. Heterojunction thin films based on multifunctional metal oxides for photovoltaic application

    SciTech Connect (OSTI)

    Prabhu, M.; Soundararajan, N.; Ramachandran, K. [School of Physics, Madurai Kamaraj University, Madurai - 625021 (India); Marikkannan, M.; Mayandi, J. [School of Chemistry, Madurai Kamaraj University, Madurai - 625021 (India)

    2014-04-24T23:59:59.000Z

    Metal oxides based multifunctional heterojunction thin films of ZnO/SnO{sub 2} and ZnO/SnO{sub 2}/CuO QDs were prepared by spin-coating technique. The crystallographic properties and the surface morphologies of the films were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The optical absorption studies revealed that the film thickness has considerable effect on the band gap values and is found to be in the range of 3.73–3.48 eV. The photoluminescence spectra showed several weak visible emission peaks related to the deep level defects (450-575 nm). Finally, the current density-voltage (J-V) characteristic of ZnO/SnO{sub 2}/CuO QDs (ZSCI) based heterojunction thin film coated on ITO is also reported.

  17. Semiconductor electrode with improved photostability characteristics

    DOE Patents [OSTI]

    Frank, A.J.

    1985-02-19T23:59:59.000Z

    An electrode is described for use in photoelectrochemical cells having an electrolyte which includes an aqueous constituent. The electrode consists of a semiconductor and a hydrophobic film disposed between the semiconductor and the aqueous constituent. The hydrophobic film is adapted to permit charges to pass therethrough while substantially decreasing the activity of the aqueous constituent at the semiconductor surface thereby decreasing the photodegradation of the semiconductor electrode.

  18. Semiconductor nanocrystal-based phagokinetic tracking

    DOE Patents [OSTI]

    Alivisatos, A Paul; Larabell, Carolyn A; Parak, Wolfgang J; Le Gros, Mark; Boudreau, Rosanne

    2014-11-18T23:59:59.000Z

    Methods for determining metabolic properties of living cells through the uptake of semiconductor nanocrystals by cells. Generally the methods require a layer of neutral or hydrophilic semiconductor nanocrystals and a layer of cells seeded onto a culture surface and changes in the layer of semiconductor nanocrystals are detected. The observed changes made to the layer of semiconductor nanocrystals can be correlated to such metabolic properties as metastatic potential, cell motility or migration.

  19. Review: Semiconductor Quantum Light Sources

    E-Print Network [OSTI]

    Andrew J Shields

    2007-04-03T23:59:59.000Z

    Lasers and LEDs display a statistical distribution in the number of photons emitted in a given time interval. New applications exploiting the quantum properties of light require sources for which either individual photons, or pairs, are generated in a regulated stream. Here we review recent research on single-photon sources based on the emission of a single semiconductor quantum dot. In just a few years remarkable progress has been made in generating indistinguishable single-photons and entangled photon pairs using such structures. It suggests it may be possible to realise compact, robust, LED-like semiconductor devices for quantum light generation.

  20. Semiconductor films on flexible iridium substrates

    DOE Patents [OSTI]

    Goyal, Amit

    2005-03-29T23:59:59.000Z

    A laminate semiconductor article includes a flexible substrate, an optional biaxially textured oxide buffer system on the flexible substrate, a biaxially textured Ir-based buffer layer on the substrate or the buffer system, and an epitaxial layer of a semiconductor. Ir can serve as a substrate with an epitaxial layer of a semiconductor thereon.

  1. Semiconductor bridge (SCB) igniter

    DOE Patents [OSTI]

    Bickes, Jr., Robert W. (Albuquerque, NM); Schwarz, Alfred C. (Albuquerque, NM)

    1987-01-01T23:59:59.000Z

    In an explosive device comprising an explosive material which can be made to explode upon activation by activation means in contact therewith; electrical activation means adaptable for activating said explosive material such that it explodes; and electrical circuitry in operation association with said activation means; there is an improvement wherein said activation means is an electrical material which, at an elevated temperature, has a negative temperature coefficient of electrical resistivity and which has a shape and size and an area of contact with said explosive material sufficient that it has an electrical resistance which will match the resistance requirements of said associated electrical circuitry when said electrical material is operationally associated with said circuitry, and wherein said electrical material is polycrystalline; or said electrical material is crystalline and (a) is mounted on a lattice matched substrate or (b) is partially covered with an intimately contacting metallization area which defines its area of contact with said explosive material.

  2. Nonadiabatic electron transfer at the nanoscale tin-oxide semiconductor/aqueous solution interface

    E-Print Network [OSTI]

    published as an Advance Article on the web 28th January 2004 Photo-excitation of chromophoric metal forward and back electron transfer reactions involving molecular dyes and wide bandgap semiconductors words, electro- nic coupling rather than nuclear motion appears to govern the reaction dynamics

  3. High-Temperature Thermoelectric Characterization of IIIV Semiconductor Thin Films by Oxide Bonding

    E-Print Network [OSTI]

    High-Temperature Thermoelectric Characterization of III­V Semiconductor Thin Films by Oxide Bonding and measurement method utilizing a SiO2­SiO2 covalent bonding technique is presented for high-temperature surface passivation, and metallization with a Ti-W-N diffusion barrier. A thermoelectric material, thin

  4. High temperature thermoelectric characterization of III-V semiconductor thin films by oxide bonding

    E-Print Network [OSTI]

    Bowers, John

    bonding Je-Hyeong Bahka) , Gehong Zenga) , Joshua M. O. Zide b) , Hong Luc) , Rajeev Singhd) , Di Lianga bonding technique is developed for high temperature thermoelectric characterization of the thin film III-W-N diffusion barrier. A thermoelectric material, thin film ErAs:InGaAlAs metal/semiconductor nanocomposite

  5. Single-Crystalline Diluted Magnetic Semiconductor GaN:Mn Nanowires**

    E-Print Network [OSTI]

    Yang, Peidong

    Single-Crystalline Diluted Magnetic Semiconductor GaN:Mn Nanowires** By Heon-Jin Choi*, Han-mediated ferromagnetism. These ferromagnetic GaN:Mn nanowires represent an important class of nanometer-scale building blocks for spintronics. Theoretical studies indicate that transition-metal-doped GaN possesses

  6. 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

    2008-08-06T23:59:59.000Z

    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.

  7. Mechanical scriber for semiconductor devices

    DOE Patents [OSTI]

    Lin, P.T.

    1985-03-05T23:59:59.000Z

    A mechanical scriber using a scribing tip, such as a diamond, provides controlled scriber forces with a spring-loaded compound lever arrangement. The scribing force and range of scribing depth are adjusted by a pair of adjustable micrometer heads. A semiconductor device, such as a multilayer solar cell, can be formed into scribed strips at each layer. 5 figs.

  8. Mechanical scriber for semiconductor devices

    DOE Patents [OSTI]

    Lin, Peter T. (East Brunswick, NJ)

    1985-01-01T23:59:59.000Z

    A mechanical scriber using a scribing tip, such as a diamond, provides controlled scriber forces with a spring-loaded compound lever arrangement. The scribing force and range of scribing depth are adjusted by a pair of adjustable micrometer heads. A semiconductor device, such as a multilayer solar cell, can be formed into scribed strips at each layer.

  9. Controlled growth of semiconductor crystals

    DOE Patents [OSTI]

    Bourret-Courchesne, E.D.

    1992-07-21T23:59:59.000Z

    A method is disclosed for growth of III-V, II-VI and related semiconductor single crystals that suppresses random nucleation and sticking of the semiconductor melt at the crucible walls. Small pieces of an oxide of boron B[sub x]O[sub y] are dispersed throughout the comminuted solid semiconductor charge in the crucible, with the oxide of boron preferably having water content of at least 600 ppm. The crucible temperature is first raised to a temperature greater than the melt temperature T[sub m1] of the oxide of boron (T[sub m1]=723 K for boron oxide B[sub 2]O[sub 3]), and the oxide of boron is allowed to melt and form a reasonably uniform liquid layer between the crucible walls and bottom surfaces and the still-solid semiconductor charge. The temperature is then raised to approximately the melt temperature T[sub m2] of the semiconductor charge material, and crystal growth proceeds by a liquid encapsulated, vertical gradient freeze process. About half of the crystals grown have a dislocation density of less than 1000/cm[sup 2]. If the oxide of boron has water content less than 600 ppm, the crucible material should include boron nitride, a layer of the inner surface of the crucible should be oxidized before the oxide of boron in the crucible charge is melted, and the sum of thicknesses of the solid boron oxide layer and liquid boron oxide layer should be at least 50 [mu]m. 7 figs.

  10. Controlled growth of semiconductor crystals

    DOE Patents [OSTI]

    Bourret-Courchesne, Edith D. (Richmond, CA)

    1992-01-01T23:59:59.000Z

    A method for growth of III-V, II-VI and related semiconductor single crystals that suppresses random nucleation and sticking of the semiconductor melt at the crucible walls. Small pieces of an oxide of boron B.sub.x O.sub.y are dispersed throughout the comminuted solid semiconductor charge in the crucible, with the oxide of boron preferably having water content of at least 600 ppm. The crucible temperature is first raised to a temperature greater than the melt temperature T.sub.m1 of the oxide of boron (T.sub.m1 =723.degree. K. for boron oxide B.sub.2 O.sub.3), and the oxide of boron is allowed to melt and form a reasonably uniform liquid layer between the crucible walls and bottom surfaces and the still-solid semiconductor charge. The temperature is then raised to approximately the melt temperature T.sub.m2 of the semiconductor charge material, and crystal growth proceeds by a liquid encapsulated, vertical gradient freeze process. About half of the crystals grown have a dislocation density of less than 1000/cm.sup.2. If the oxide of boron has water content less than 600 ppm, the crucible material should include boron nitride, a layer of the inner surface of the crucible should be oxidized before the oxide of boron in the crucible charge is melted, and the sum of thicknesses of the solid boron oxide layer and liquid boron oxide layer should be at least 50 .mu.m.

  11. Rational Design and Preparation of Organic Semiconductors for use in Field Effect Transistors and Photovoltaic Cells

    E-Print Network [OSTI]

    Mauldin, Clayton Edward

    2010-01-01T23:59:59.000Z

    Distyryl Oligothiophene Semiconductors Abstract We describebonded Oligothiophene Semiconductor Side Chains Abstract Ato assemble oligothiophene semiconductors and control their

  12. Back-side readout semiconductor photomultiplier

    DOE Patents [OSTI]

    Choong, Woon-Seng; Holland, Stephen E

    2014-05-20T23:59:59.000Z

    This disclosure provides systems, methods, and apparatus related to semiconductor photomultipliers. In one aspect, a device includes a p-type semiconductor substrate, the p-type semiconductor substrate having a first side and a second side, the first side of the p-type semiconductor substrate defining a recess, and the second side of the p-type semiconductor substrate being doped with n-type ions. A conductive material is disposed in the recess. A p-type epitaxial layer is disposed on the second side of the p-type semiconductor substrate. The p-type epitaxial layer includes a first region proximate the p-type semiconductor substrate, the first region being implanted with p-type ions at a higher doping level than the p-type epitaxial layer, and a second region disposed on the first region, the second region being doped with p-type ions at a higher doping level than the first region.

  13. Probing Excitonic Dark States in Single-layer Tungsten Disulfide

    E-Print Network [OSTI]

    Ye, Ziliang; O'Brien, Kevin; Zhu, Hanyu; Yin, Xiaobo; Wang, Yuan; Louie, Steven G; Zhang, Xiang

    2014-01-01T23:59:59.000Z

    Transition metal dichalcogenide (TMDC) monolayer has recently emerged as an important two-dimensional semiconductor with promising potentials for electronic and optoelectronic devices. Unlike semi-metallic graphene, layered TMDC has a sizable band gap. More interestingly, when thinned down to a monolayer, TMDC transforms from an indirect bandgap to a direct bandgap semiconductor, exhibiting a number of intriguing optical phenomena such as valley selective circular dichroism, doping dependent charged excitons, and strong photocurrent responses. However, the fundamental mechanism underlying such a strong light-matter interaction is still under intensive investigation. The observed optical resonance was initially considered to be band-to-band transitions. In contrast, first-principle calculations predicted a much larger quasiparticle band gap size and an optical response that is dominated by excitonic effects. Here, we report experimental evidence of the exciton dominance mechanism by discovering a series of exc...

  14. Phase-locked semiconductor laser array with separate contacts

    SciTech Connect (OSTI)

    Katz, J.; Kapon, E.; Lindsey, C.; Margalit, S.; Shreter, U.; Yariv, A.

    1983-09-15T23:59:59.000Z

    A new monolithic phase-locked semiconductor laser array has been fabricated. Employing two-level metallization, each of the eight elements in the array has a separate contact, thus making it possible to compensate for device nonuniformities and control the near-field and far-field patterns. Threshold currents are approximately 60 mA for each 5-..mu..m-wide laser in the array. Phase locking has been observed via the narrowing of the far-field pattern. Experimental results are compared to those obtained from the same arrays operated with all the lasers connected in parallel.

  15. Investigation of redox processes at semiconductor electrode liquid junctions

    SciTech Connect (OSTI)

    Koval, C.A.

    1990-08-01T23:59:59.000Z

    Research in fundamental aspects of photoelectrochemical cells has been in the following areas: chemical probes for hot carrier processes, electrostatic theory for describing electrical interactions at interfaces, and kinetics of electron transfer at ideal semiconductor solution interfaces. Our goal is to achieve a better understanding of dark and photo-induced current flow at the semiconductor electrode/redox electrolyte interface (SEI) so that devices and processes utilizing this interface for solar energy conversion can be developed or improved. Our most important accomplishment has been the development of a redox system capable of detecting hot electrons at the p-InP/acetonitrile interface. Also, we have examined electrostatic theory for the image potential of an ion as a function of distance from the SEI. Finally, our group was one of the first to realize that the 2-dimensional metal chalcogenides (MC) are excellent materials for fundamental studies of electron transfer at the SEI. One of the chief potential advantages for use of MC's is the formation of semiconductor/liquid junctions with nearly ideal electrochemical properties. 27 refs., 1 fig.

  16. Measuring Speedy Electrons in Silicon

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

    scientists have taken snapshots of this very brief band-gap jump and timed it at 450 attoseconds. Image: Stephen Leone The entire semiconductor industry, not to mention...

  17. Spectroscopy of Charge Carriers and Traps in Field-Doped Single Crystal Organic Semiconductors

    SciTech Connect (OSTI)

    Zhu, Xiaoyang

    2014-12-10T23:59:59.000Z

    The proposed research aims to achieve quantitative, molecular level understanding of charge carriers and traps in field-doped crystalline organic semiconductors via in situ linear and nonlinear optical spectroscopy, in conjunction with transport measurements and molecular/crystal engineering. Organic semiconductors are emerging as viable materials for low-cost electronics and optoelectronics, such as organic photovoltaics (OPV), organic field effect transistors (OFETs), and organic light emitting diodes (OLEDs). Despite extensive studies spanning many decades, a clear understanding of the nature of charge carriers in organic semiconductors is still lacking. It is generally appreciated that polaron formation and charge carrier trapping are two hallmarks associated with electrical transport in organic semiconductors; the former results from the low dielectric constants and weak intermolecular electronic overlap while the latter can be attributed to the prevalence of structural disorder. These properties have lead to the common observation of low charge carrier mobilities, e.g., in the range of 10-5 - 10-3 cm2/Vs, particularly at low carrier concentrations. However, there is also growing evidence that charge carrier mobility approaching those of inorganic semiconductors and metals can exist in some crystalline organic semiconductors, such as pentacene, tetracene and rubrene. A particularly striking example is single crystal rubrene (Figure 1), in which hole mobilities well above 10 cm2/Vs have been observed in OFETs operating at room temperature. Temperature dependent transport and spectroscopic measurements both revealed evidence of free carriers in rubrene. Outstanding questions are: what are the structural features and physical properties that make rubrene so unique? How do we establish fundamental design principles for the development of other organic semiconductors of high mobility? These questions are critically important but not comprehensive, as the nature of charge carriers is known to evolve as the carrier concentration increases, due to the presence of intrinsic disorder in organic semiconductors. Thus, a complementary question is: how does the nature of charge transport change as a function of carrier concentration?

  18. Downloaded 03 Apr 2013 to 147.173.59.170. This article is copyrighted as indicated in the abstract. Reuse of AIP content is subject to the terms at: http://apl.aip.org/about/rights_and_permissions High conductivity in Si-doped GaN wires

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ;High conductivity in Si-doped GaN wires P. Tchoulfian,1,2,a) F. Donatini,2 F. Levy,1 B. Amstatt,1 P-dependent resistivity measurements have been performed on single Si-doped GaN microwires grown by catalyst-free metal.1063/1.4799167] GaN is a wide band gap III-V semiconductor ($3.4 eV) currently used as the basic material for planar

  19. Enhanced von Weizsäcker Wang-Govind-Carter kinetic energy density functional for semiconductors

    SciTech Connect (OSTI)

    Shin, Ilgyou [Department of Chemistry, Princeton University, Princeton, New Jersey 08544-1009 (United States)] [Department of Chemistry, Princeton University, Princeton, New Jersey 08544-1009 (United States); Carter, Emily A., E-mail: eac@princeton.edu [Department of Mechanical and Aerospace Engineering, Program in Applied and Computational Mathematics, and Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey 08544-5263 (United States)

    2014-05-14T23:59:59.000Z

    We propose a new form of orbital-free (OF) kinetic energy density functional (KEDF) for semiconductors that is based on the Wang-Govind-Carter (WGC99) nonlocal KEDF. We enhance within the latter the semi-local von Weizsäcker KEDF term, which is exact for a single orbital. The enhancement factor we introduce is related to the extent to which the electron density is localized. The accuracy of the new KEDF is benchmarked against Kohn-Sham density functional theory (KSDFT) by comparing predicted energy differences between phases, equilibrium volumes, and bulk moduli for various semiconductors, along with metal-insulator phase transition pressures. We also compare point defect and (100) surface energies in silicon for a broad test of its applicability. This new KEDF accurately reproduces the exact non-interacting kinetic energy of KSDFT with only one additional adjustable parameter beyond the three parameters in the WGC99 KEDF; it exhibits good transferability between semiconducting to metallic silicon phases and between various III-V semiconductors without parameter adjustment. Overall, this KEDF is more accurate than previously proposed OF KEDFs (e.g., the Huang-Carter (HC) KEDF) for semiconductors, while the computational efficiency remains at the level of the WGC99 KEDF (several hundred times faster than the HC KEDF). This accurate, fast, and transferable new KEDF holds considerable promise for large-scale OFDFT simulations of metallic through semiconducting materials.

  20. Lateral coupled cavity semiconductor laser

    SciTech Connect (OSTI)

    Salzman, J.; Lang, R.; Yariv, A.

    1985-08-01T23:59:59.000Z

    We report the fabrication and operation of a lateral coupled cavity semiconductor laser that consists of two phase-locked parallel lasers of different lengths and with separate electrical contacts. Mode selectivity that results from the interaction between the two supermodes is investigated experimentally. Frequency selectivity and tunability are obtained by controlling the current to each laser separately. Highly stable single mode operation is also demonstrated.

  1. Compound semiconductor optical waveguide switch

    DOE Patents [OSTI]

    Spahn, Olga B.; Sullivan, Charles T.; Garcia, Ernest J.

    2003-06-10T23:59:59.000Z

    An optical waveguide switch is disclosed which is formed from III-V compound semiconductors and which has a moveable optical waveguide with a cantilevered portion that can be bent laterally by an integral electrostatic actuator to route an optical signal (i.e. light) between the moveable optical waveguide and one of a plurality of fixed optical waveguides. A plurality of optical waveguide switches can be formed on a common substrate and interconnected to form an optical switching network.

  2. Routing for analog chip design at NXP semiconductors

    E-Print Network [OSTI]

    Utrecht, Universiteit

    Routing for analog chip design at NXP semiconductors Marjan van den Akker Theo Beelen Rob H.O. Box 80.089 3508 TB Utrecht The Netherlands #12;Routing for analog chip designs at NXP Semiconductors.1 NXP Semiconductors NXP Semiconductors N.V. (Nasdaq: NXPI) is a global semiconductor company and a long

  3. Characterization and electrical modeling of semiconductors bridges

    SciTech Connect (OSTI)

    Marx, K.D. [Sandia National Labs., Livermore, CA (United States); Bickes, R.W. Jr.; Wackerbarth, D.E. [Sandia National Labs., Albuquerque, NM (United States)

    1997-03-01T23:59:59.000Z

    Semiconductor bridges (SCBs) are finding increased use as initiators for explosive and pyrotechnic devices. They offer advantages in reduced voltage and energy requirements, coupled with excellent safety features. The design of explosive systems which implement either SCBs or metal bridgewires can be facilitated through the use of electrical simulation software such as the PSpice{reg_sign} computer code. A key component in the electrical simulation of such systems is an electrical model of the bridge. This report has two objectives: (1) to present and characterize electrical data taken in tests of detonators which employ SCBs with BNCP as the explosive powder; and (2) to derive appropriate electrical models for such detonators. The basis of such models is a description of the resistance as a function of energy deposited in the SCB. However, two important features which must be added to this are (1) the inclusion of energy loss through such mechanisms as ohmic heating of the aluminum lands and heat transfer from the bridge to the surrounding media; and (2) accounting for energy deposited in the SCB through heat transfer to the bridge from the explosive powder after the powder ignites. The modeling procedure is entirely empirical; i.e., models for the SCB resistance and the energy gain and loss have been estimated from experimental data taken over a range of firing conditions. We present results obtained by applying the model to the simulation of SCB operation in representative tests.

  4. Thermal Issues in Casimir Forces Between Conductors and Semiconductors

    E-Print Network [OSTI]

    K. A. Milton; Iver Brevik; Simen A. Ellingsen

    2012-07-20T23:59:59.000Z

    The Casimir effect between metal surfaces has now been well-verified at the few-percent level experimentally. However, the temperature dependence has never been observed in the laboratory, since all experiments are conducted at room temperature. The temperature dependence for the related Casimir-Polder force between an atom and a bulk material has, in contrast, been observed between a BEC and a silica substrate, with the environment and the silica held at different temperatures. There is a controversy about the temperature dependence for the force between metals, having to do with the magnitude of the linear temperature term for both low and high temperature, the latter being most prominent at large distances. There are also related anomalies pertaining to semiconductors. The status of this controversy, and of the relevant experiments, are reviewed in this report.

  5. Optical devices featuring textured semiconductor layers

    DOE Patents [OSTI]

    Moustakas, Theodore D. (Dover, MA); Cabalu, Jasper S. (Cary, NC)

    2012-08-07T23:59:59.000Z

    A semiconductor sensor, solar cell or emitter, or a precursor therefor, has a substrate and one or more textured semiconductor layers deposited onto the substrate. The textured layers enhance light extraction or absorption. Texturing in the region of multiple quantum wells greatly enhances internal quantum efficiency if the semiconductor is polar and the quantum wells are grown along the polar direction. Electroluminescence of LEDs of the invention is dichromatic, and results in variable color LEDs, including white LEDs, without the use of phosphor.

  6. Optical devices featuring textured semiconductor layers

    DOE Patents [OSTI]

    Moustakas, Theodore D. (Dover, MA); Cabalu, Jasper S. (Cary, NC)

    2011-10-11T23:59:59.000Z

    A semiconductor sensor, solar cell or emitter, or a precursor therefor, has a substrate and one or more textured semiconductor layers deposited onto the substrate. The textured layers enhance light extraction or absorption. Texturing in the region of multiple quantum wells greatly enhances internal quantum efficiency if the semiconductor is polar and the quantum wells are grown along the polar direction. Electroluminescence of LEDs of the invention is dichromatic, and results in variable color LEDs, including white LEDs, without the use of phosphor.

  7. Stretchable semiconductor elements and stretchable electrical circuits

    DOE Patents [OSTI]

    Rogers, John A. (Champaign, IL); Khang, Dahl-Young (Seoul, KR); Menard, Etienne (Durham, NC)

    2009-07-07T23:59:59.000Z

    The invention provides methods and devices for fabricating printable semiconductor elements and assembling printable semiconductor elements onto substrate surfaces. Methods, devices and device components of the present invention are capable of generating a wide range of flexible electronic and optoelectronic devices and arrays of devices on substrates comprising polymeric materials. The present invention also provides stretchable semiconductor structures and stretchable electronic devices capable of good performance in stretched configurations.

  8. Novel spin-electronic properties of BC{sub 7} sheets induced by strain

    SciTech Connect (OSTI)

    Xu, Lei; Dai, ZhenHong, E-mail: zhdai@ytu.edu.cn; Sui, PengFei; Sun, YuMing; Wang, WeiTian [Computational Physics Laboratory, Institute of Opto-Electronic Information Science and Technology, Yantai University, Yantai 264005 (China)

    2014-11-01T23:59:59.000Z

    Based on first-principles calculations, the authors have investigated the electronic and magnetic properties of BC{sub 7} sheets with different planar strains. It is found that metal–semiconductor transition appears at the biaxial strain of 15.5%, and the sheets are characteristic of spin-polarized semiconductor with a zero band-gap. The band-gap rapidly increases with strain, and reaches a maximum value of 0.60 eV at the strain of 20%. Subsequently, the band-gap decreases until the strain reaches up to 22% and shows a semiconductor-half metal transformation. It will further present metal properties until the strain is up to the maximum value of 35%. The magnetic moments also have some changes induced by biaxial strain. The numerical analysis shows that the two-dimensional distortions have great influences on the magnetic moments. The novel spin-electronic properties make BC{sub 7} sheets have potential applications in future spintronic nanodevices.

  9. Low Energy Ion Implantationin Semiconductor Manufacturing | U...

    Office of Science (SC) Website

    Low Energy Ion Implantation in Semiconductor Manufacturing Nuclear Physics (NP) NP Home About Research Facilities Science Highlights Benefits of NP Applications of Nuclear Science...

  10. Climate VISION: Private Sector Initiatives: Semiconductors: Work...

    Office of Scientific and Technical Information (OSTI)

    of EPA. The plan describes actions the industry intends to take to achieve its Climate VISION goal by 2010. Read the Semiconductor Industry Association Work Plan (PDF 94...

  11. Climate VISION: Private Sector Initiatives: Semiconductors: Resources...

    Office of Scientific and Technical Information (OSTI)

    to reduce high global warming potential (GWP) greenhouse gas emissions by following a pollution prevention strategy. Today, nearly 80 percent of U.S. semiconductor manufacturers...

  12. Crossover from tunneling to meta.llic behavior in superconductofgsemiconductor contacts

    E-Print Network [OSTI]

    Woodall, Jerry M.

    -dominated transport at the superconductor-semiconductor contacts as Schottky barrier thickness decreases of such a crossover in a thin-film structure, and are of interest for investigations of hybrid superconductor-semiconductorCrossover from tunneling to meta.llic behavior in superconductofgsemiconductor contacts A. W

  13. Isovalent Anion Substitution in Ga-Mn-pnictide Ferromagnetic Semiconductors

    E-Print Network [OSTI]

    Stone, Peter

    2010-01-01T23:59:59.000Z

    a so-called diluted magnetic semiconductor (DMS). DMSs arein heavily doped magnetic semiconductors as the probabilitythis method to magnetic semiconductors, the 6×6 k·p matrix

  14. Performance of Adaptive DualDropping ILUT Preconditioners in Semiconductor

    E-Print Network [OSTI]

    Zhang, Jun

    Performance of Adaptive Dual­Dropping ILUT Preconditioners in Semiconductor Dopant Diffusion for iterative solution of sparse linear systems arising in semiconductor dopant diffusion modeling resolution, timestep in the adaptive ODE integrator and the problem physics. Key words: semiconductor TCAD

  15. Semiconductor Capabilities in the U.S. and Industrializing Asia

    E-Print Network [OSTI]

    Brown, Clair; Linden, Greg

    2008-01-01T23:59:59.000Z

    data. Table 2: U.S. Semiconductor Engineers By Location,medium-sized U.S. semiconductor companies, which togetherto represent all U.S. semiconductor firms. The total

  16. Stabilization of Electrocatalytic Metal Nanoparticles at Metal...

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

    Electrocatalytic Metal Nanoparticles at Metal-Metal Oxide-Graphene Triple Junction Points. Stabilization of Electrocatalytic Metal Nanoparticles at Metal-Metal Oxide-Graphene...

  17. Spectroscopy of Charge Carriers and Traps in Field-Doped Organic Semiconductors

    SciTech Connect (OSTI)

    Zhu, Xiaoyang; Frisbie, C Daniel

    2012-08-13T23:59:59.000Z

    This research project aims to achieve quantitative and molecular level understanding of charge carriers and traps in field-doped organic semiconductors via in situ optical absorption spectroscopy, in conjunction with time-resolved electrical measurements. During the funding period, we have made major progress in three general areas: (1) probed charge injection at the interface between a polymeric semiconductor and a polymer electrolyte dielectric and developed a thermodynamic model to quantitatively describe the transition from electrostatic to electrochemical doping; (2) developed vibrational Stark effect to probe electric field at buried organic semiconductor interfaces; (3) used displacement current measurement (DCM) to study charge transport at organic/dielectric interfaces and charge injection at metal/organic interfaces.

  18. Problems in the theory of thermal Casimir force between dielectrics and semiconductors

    E-Print Network [OSTI]

    G. L. Klimchitskaya; B. Geyer

    2008-02-26T23:59:59.000Z

    The application of the Lifshitz theory to describe the thermal Casimir force between dielectrics and semiconductors is considered. It is shown that for all true dielectrics (i.e., for all materials having zero conductivity at zero temperature) the inclusion of a nonzero conductivity arising at nonzero temperature into the model of dielectric response leads to the violation of the Nernst heat theorem. This result refers equally to simple insulators, intrinsic semiconductors, Mott-Hubbard dielectrics and doped semiconductors with doping concentration below a critical value. We demonstrate that in the insulator-metal transition the Casimir free energy changes abruptly irrespective of whether the conductivity changes continuously or discontinuously. The application of the Lifshitz formula to polar dielectrics results in large thermal correction that is linear in temperature. A rule is formulated on how to apply the Lifshitz theory to real materials in agreement with thermodynamics and experiment.

  19. Electronic and thermoelectric transport in semiconductor and metallic superlattices

    E-Print Network [OSTI]

    cooling of the electron gas. The HIT cooler is based on either a single barrier or a multi barrier than the Fermi energy, Ef) are emitted above the bar- rier, electron­electron and electron

  20. Localized Electron States Near a Metal-Semiconductor Nanocontact

    E-Print Network [OSTI]

    Demchenko, Denis O.; Wang, Lin-Wang

    2007-01-01T23:59:59.000Z

    L. W. Wang, and A. P. Alivisatos, Nature 430, 190 (2004). [A. K. L. Lim, A. P. Alivisatos, and P. L. McEuen, NatureB. Lee, L. -W. Wang, A. P. Alivisatos, and M. Salmeron, J.

  1. Spin injection and transport in semiconductor and metal nanostructures

    E-Print Network [OSTI]

    Zhu, Lei

    2009-01-01T23:59:59.000Z

    spin-momentum-transfer effect (SMT), which was theoreticallyaccess memory (DRAM). SMT utilizes the momentum transferto magnetize a unit cell. This SMT effect becomes prominent

  2. Metal-optic and Plasmonic Semiconductor-based Nanolasers

    E-Print Network [OSTI]

    Lakhani, Amit

    2012-01-01T23:59:59.000Z

    cubic wavelengths). The ultra-small laser volume is achievedthey are useful for ultra-small laser designs. Unlikeelectrically injected lasers based on ultra-thin epitaxial

  3. Metal Oxide Semiconductor Nanoparticles Pave the Way for Medical Innovation

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

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHighand Retrievals from aRod EggertMercuryAdvanced MaterialsPortal-

  4. Thermal Transport in Semiconductors and Metals from First-Principle

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

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del SolStrengthening a solidSynthesis of 2DandEnergy Thereceiver survey system

  5. A Low Temperature Fully Lithographic Process For Metal–Oxide Field-Effect Transistors

    E-Print Network [OSTI]

    Sodini, Charles G.

    We report a low temperature ( ~ 100à °C) lithographic method for fabricating hybrid metal oxide/organic field-effect transistors (FETs) that combine a zinc-indium-oxide (ZIO) semiconductor channel and organic, parylene, ...

  6. PROTECTIVE SURFACE COATINGS ON SEMICONDUCTOR NUCLEAR RADIATION DETECTORS

    E-Print Network [OSTI]

    Hansen, W.L.

    2010-01-01T23:59:59.000Z

    ON SEMICONDUCTOR NUCLEAR RADIATION DETECTORS W. L. Hansen,COATINGS ON SEMICONDUCTOR NUCLEAR RADIATION DETECTORS* W. L.the use of germanium nuclear radiation detec­ tors, a new

  7. New ALS Technique Guides IBM in Next-Generation Semiconductor...

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

    New ALS Technique Guides IBM in Next-Generation Semiconductor Development New ALS Technique Guides IBM in Next-Generation Semiconductor Development Print Wednesday, 21 January 2015...

  8. Engineering Density of States of Earth Abundant Semiconductors...

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

    of States of Earth Abundant Semiconductors for Enhanced Thermoelectric Power Factor Engineering Density of States of Earth Abundant Semiconductors for Enhanced Thermoelectric...

  9. advanced semiconductor manufacturing: Topics by E-print Network

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

    Websites Summary: Business and Manufacturing Tohru Ogawa Semiconductor Company Sony Corporation 12;WISE 2000 ContentsContents Paradigm Shift in Semiconductor Business...

  10. Webinar: Opportunities for Wide Bandgap Semiconductor Power Electronic...

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

    Opportunities for Wide Bandgap Semiconductor Power Electronics for Hydrogen and Fuel Cell Applications Webinar: Opportunities for Wide Bandgap Semiconductor Power Electronics...

  11. Charge-carrier transport in amorphous organic semiconductors

    E-Print Network [OSTI]

    Limketkai, Benjie, 1982-

    2008-01-01T23:59:59.000Z

    Since the first reports of efficient luminescence and absorption in organic semiconductors, organic light-emitting devices (OLEDs) and photovoltaics (OPVs) have attracted increasing interest. Organic semiconductors have ...

  12. Optic probe for semiconductor characterization

    DOE Patents [OSTI]

    Sopori, Bhushan L. (Denver, CO); Hambarian, Artak (Yerevan, AM)

    2008-09-02T23:59:59.000Z

    Described herein is an optical probe (120) for use in characterizing surface defects in wafers, such as semiconductor wafers. The optical probe (120) detects laser light reflected from the surface (124) of the wafer (106) within various ranges of angles. Characteristics of defects in the surface (124) of the wafer (106) are determined based on the amount of reflected laser light detected in each of the ranges of angles. Additionally, a wafer characterization system (100) is described that includes the described optical probe (120).

  13. Chalcogels : porous metal-chalcogenide networks from main-group metal ions. Effect of surface polarizability on selectivity in gas separation.

    SciTech Connect (OSTI)

    Bag, S.; Kanatzidis, M. G.; Materials Science Division; Northwestern Univ.

    2010-10-06T23:59:59.000Z

    We report the synthesis of metal-chalcogenide gels and aerogels from anionic chalcogenide clusters and linking metal ions. Metal ions such as Sb{sup 3+} and Sn{sup 2+}, respectively chelated with tartrate and acetate ligands, react in solution with the chalcogenide clusters to form extended polymeric networks that exhibit gelation phenomena. Chalcogenide cluster anions with different charge densities, such as [Sn{sub 2}S{sub 6}]{sup 4-} and [SnS{sub 4}]{sup 4-}, were employed. In situ rheological measurements during gelation showed that a higher charge density on the chalcogenide cluster favors formation of a rigid gel network. Aerogels obtained from the gels after supercritical drying have BET surface areas from 114 to 368 m{sup 2}/g. Electron microscopy images coupled with nitrogen adsorption measurements showed the pores are micro (below 2 nm), meso (2-50 nm), and macro (above 50 nm) regions. These chalcogels possess band gaps in the range of 1.00-2.00 eV and selectively adsorb polarizable gases. A 2-fold increase in selectivity toward CO{sub 2}/C{sub 2}H{sub 6} over H{sub 2} was observed for the Pt/Sb/Ge{sub 4}Se{sub 10}-containing aerogel compared to aerogel containing Pt{sub 2}Ge{sub 4}S{sub 10}. The experimental results suggest that high selectivity in gas adsorption is achievable with high-surface-area chalcogenide materials containing heavy polarizable elements.

  14. Nonlinear Peltier effect in semiconductors Mona Zebarjadia

    E-Print Network [OSTI]

    Nonlinear Peltier effect in semiconductors Mona Zebarjadia Department of Electrical Engineering; published online 18 September 2007 Nonlinear Peltier coefficient of a doped InGaAs semiconductor is calculated numerically using the Monte Carlo technique. The Peltier coefficient is also obtained analytically

  15. Preparation of a semiconductor thin film

    DOE Patents [OSTI]

    Pehnt, M.; Schulz, D.L.; Curtis, C.J.; Ginley, D.S.

    1998-01-27T23:59:59.000Z

    A process is disclosed for the preparation of a semiconductor film. The process comprises depositing nanoparticles of a semiconductor material onto a substrate whose surface temperature during nanoparticle deposition thereon is sufficient to cause substantially simultaneous fusion of the nanoparticles to thereby coalesce with each other and effectuate film growth.

  16. Ultra-high speed semiconductor lasers

    SciTech Connect (OSTI)

    Lau, K.Y.; Yariv, A.

    1985-02-01T23:59:59.000Z

    Recent progress on semiconductor lasers having a very high direct modulation bandwidth of beyond 10 GHz are described. Issues related to application of these lasers in actual systems are addressed. Possibilities of further extending the bandwidth of semiconductor lasers are examined.

  17. Preparation of a semiconductor thin film

    DOE Patents [OSTI]

    Pehnt, Martin (TuBingen, DE); Schulz, Douglas L. (Denver, CO); Curtis, Calvin J. (Lakewood, CO); Ginley, David S. (Evergreen, CO)

    1998-01-01T23:59:59.000Z

    A process for the preparation of a semiconductor film. The process comprises depositing nanoparticles of a semiconductor material onto a substrate whose surface temperature during nanoparticle deposition thereon is sufficient to cause substantially simultaneous fusion of the nanoparticles to thereby coalesce with each other and effectuate film growth.

  18. Hybrid anode for semiconductor radiation detectors

    DOE Patents [OSTI]

    Yang, Ge; Bolotnikov, Aleksey E; Camarda, Guiseppe; Cui, Yonggang; Hossain, Anwar; Kim, Ki Hyun; James, Ralph B

    2013-11-19T23:59:59.000Z

    The present invention relates to a novel hybrid anode configuration for a radiation detector that effectively reduces the edge effect of surface defects on the internal electric field in compound semiconductor detectors by focusing the internal electric field of the detector and redirecting drifting carriers away from the side surfaces of the semiconductor toward the collection electrode(s).

  19. Photo deposition of metal with far uv radiation

    SciTech Connect (OSTI)

    Blum, S.E.; Brown, K.H.

    1984-05-29T23:59:59.000Z

    A method for depositing a refractory metal onto a substrate is described wherein a carbonyl compound vapor of the metal in the vicinity of or on the substrate is photodecomposed by ultraviolet radiation of wavelengths less than 200 nm. This causes the release of atoms of the metal, which then condense onto the substrate. In an example, a tungsten layer is photodeposited by this method onto a GaAs semiconductor layer to form a Schottky barrier diode.

  20. Novel room temperature ferromagnetic semiconductors

    SciTech Connect (OSTI)

    Gupta, Amita

    2004-11-01T23:59:59.000Z

    Today's information world, bits of data are processed by semiconductor chips, and stored in the magnetic disk drives. But tomorrow's information technology may see magnetism (spin) and semiconductivity (charge) combined in one 'spintronic' device that exploits both charge and 'spin' to carry data (the best of two worlds). Spintronic devices such as spin valve transistors, spin light emitting diodes, non-volatile memory, logic devices, optical isolators and ultra-fast optical switches are some of the areas of interest for introducing the ferromagnetic properties at room temperature in a semiconductor to make it multifunctional. The potential advantages of such spintronic devices will be higher speed, greater efficiency, and better stability at a reduced power consumption. This Thesis contains two main topics: In-depth understanding of magnetism in Mn doped ZnO, and our search and identification of at least six new above room temperature ferromagnetic semiconductors. Both complex doped ZnO based new materials, as well as a number of nonoxides like phosphides, and sulfides suitably doped with Mn or Cu are shown to give rise to ferromagnetism above room temperature. Some of the highlights of this work are discovery of room temperature ferromagnetism in: (1) ZnO:Mn (paper in Nature Materials, Oct issue, 2003); (2) ZnO doped with Cu (containing no magnetic elements in it); (3) GaP doped with Cu (again containing no magnetic elements in it); (4) Enhancement of Magnetization by Cu co-doping in ZnO:Mn; (5) CdS doped with Mn, and a few others not reported in this thesis. We discuss in detail the first observation of ferromagnetism above room temperature in the form of powder, bulk pellets, in 2-3 mu-m thick transparent pulsed laser deposited films of the Mn (<4 at. percent) doped ZnO. High-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) spectra recorded from 2 to 200nm areas showed homogeneous distribution of Mn substituting for Zn a 2+ state in the ZnO lattice. Ferromagnetic Resonance (FMR) technique is used to confirm the existence of ferromagnetic ordering at temperatures as high as 425K. The ab initio calculations were found to be consistent with the observation of ferromagnetism arising from fully polarized Mn 2+ state. The key to observed room temperature ferromagnetism in this system is the low temperature processing, which prevents formation of clusters, secondary phases and the host ZnO from becoming n-type. The electronic structure of the same Mn doped ZnO thin films studied using XAS, XES and RIXS, revealed a strong hybridization between Mn 3d and O 2p states, which is an important characteristic of a Dilute magnetic Semiconductor (DMS). It is shown that the various processing conditions like sintering temperature, dopant concentration and the properties of precursors used for making of DMS have a great influence on the final properties. Use of various experimental techniques to verify the physical properties, and to understand the mechanism involved to give rise to ferromagnetism is presented. Methods to improve the magnetic moment in Mn doped ZnO are also described. New promising DMS materials (such as Cu doped ZnO are explored). The demonstrated new capability to fabricate powder, pellets, and thin films of room temperature ferromagnetic semiconductors thus makes possible the realization of a wide range of complex elements for a variety of new multifunctional phenomena related to Spintronic devices as well as magneto-optic components.

  1. 370 IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING, VOL. 23, NO. 3, AUGUST 2010 Statistical Detection of Defect Patterns

    E-Print Network [OSTI]

    Zhou, Shiyu

    and cause higher scrap rate, and therefore should be controlled tightly. In semiconductor industry- faces. Typical examples include hot-rolling processes produc- ing sheet metal, and fabrication processes of Industrial and Systems Engineer- ing, University of Wisconsin-Madison, Madison, WI 53706 USA (e-mail: qzhou3

  2. Investigation of the basic physics of high efficiency semiconductor hot carrier solar cell. Annual status report, 31 May 1994-30 May 1995

    SciTech Connect (OSTI)

    Alfano, R.R.; Wang, W.B.; Mohaidat, J.M.; Cavicchia, M.A.; Raisky, O.Y.

    1995-05-01T23:59:59.000Z

    The main purpose of this research program is to investigate potential semiconductor materials and their multi-band-gap MQW (multiple quantum wells) structures for high efficiency solar cells for aerospace and commercial applications. The absorption and PL (photoluminescence) spectra, the carrier dynamics, and band structures have been investigated for semiconductors of InP, GaP, GaInP, and InGaAsP/InP MQW structures, and for semiconductors of GaAs and AlGaAs by previous measurements. The barrier potential design criteria for achieving maximum energy conversion efficiency, and the resonant tunneling time as a function of barrier width in high efficiency MQW solar cell structures have also been investigated in the first two years. Based on previous carrier dynamics measurements and the time-dependent short circuit current density calculations, an InAs/InGaAs - InGaAs/GaAs - GaAs/AlGaAs MQW solar cell structure with 15 bandgaps has been designed. The absorption and PL spectra in InGaAsP/InP bulk and MQW structures were measured at room temperature and 77 K with different pump wavelength and intensity, to search for resonant states that may affect the solar cell activities. Time-resolved IR absorption for InGaAsP/InP bulk and MQW structures has been measured by femtosecond visible-pump and IR-probe absorption spectroscopy. This, with the absorption and PL measurements, will be helpful to understand the basic physics and device performance in multi-bandgap InAs/InGaAs - InGaAs/InP - InP/InGaP MQW solar cells. In particular, the lifetime of the photoexcited hot electrons is an important parameter for the device operation of InGaAsP/InP MQW solar cells working in the resonant tunneling conditions. Lastly, time evolution of the hot electron relaxation in GaAs has been measured in the temperature range of 4 K through 288 K using femtosecond pump-IR-probe absorption technique.

  3. Thin film solar cell including a spatially modulated intrinsic layer

    DOE Patents [OSTI]

    Guha, Subhendu (Troy, MI); Yang, Chi-Chung (Troy, MI); Ovshinsky, Stanford R. (Bloomfield Hills, MI)

    1989-03-28T23:59:59.000Z

    One or more thin film solar cells in which the intrinsic layer of substantially amorphous semiconductor alloy material thereof includes at least a first band gap portion and a narrower band gap portion. The band gap of the intrinsic layer is spatially graded through a portion of the bulk thickness, said graded portion including a region removed from the intrinsic layer-dopant layer interfaces. The band gap of the intrinsic layer is always less than the band gap of the doped layers. The gradation of the intrinsic layer is effected such that the open circuit voltage and/or the fill factor of the one or plural solar cell structure is enhanced.

  4. Transmissive metallic contact for amorphous silicon solar cells

    DOE Patents [OSTI]

    Madan, A.

    1984-11-29T23:59:59.000Z

    A transmissive metallic contact for amorphous silicon semiconductors includes a thin layer of metal, such as aluminum or other low work function metal, coated on the amorphous silicon with an antireflective layer coated on the metal. A transparent substrate, such as glass, is positioned on the light reflective layer. The metallic layer is preferably thin enough to transmit at least 50% of light incident thereon, yet thick enough to conduct electricity. The antireflection layer is preferably a transparent material that has a refractive index in the range of 1.8 to 2.2 and is approximately 550A to 600A thick.

  5. Transport Equations for Semiconductors Prof. Dr. Ansgar Jungel

    E-Print Network [OSTI]

    Jüngel, Ansgar

    - cations have been invented; for instance, semiconductor lasers, solar cells, light-emitting diodes (LED

  6. Kinetic and Macroscopic Models for Semiconductors Ansgar Jungel

    E-Print Network [OSTI]

    Jüngel, Ansgar

    Kinetic and Macroscopic Models for Semiconductors Ansgar J¨ungel Vienna University of Technology, Austria www.jungel.at.vu Ansgar J¨ungel (TU Wien) Kinetic Semiconductor Models www.jungel.at.vu 1 / 165 #12;Contents 1 Introduction 2 Semiconductor modeling Basics of semiconductor physics Kinetic models 3

  7. Heating device for semiconductor wafers

    DOE Patents [OSTI]

    Vosen, S.R.

    1999-07-27T23:59:59.000Z

    An apparatus for heat treating semiconductor wafers is disclosed. The apparatus includes a heating device which contains an assembly of light energy sources for emitting light energy onto a wafer. In particular, the light energy sources are positioned such that many different radial heating zones are created on a wafer being heated. For instance, in one embodiment, the light energy sources form a spiral configuration. In an alternative embodiment, the light energy sources appear to be randomly dispersed with respect to each other so that no discernible pattern is present. In a third alternative embodiment of the present invention, the light energy sources form concentric rings. Tuning light sources are then placed in between the concentric rings of light. 4 figs.

  8. Heating device for semiconductor wafers

    DOE Patents [OSTI]

    Vosen, Steven R. (Berkeley, CA)

    1999-01-01T23:59:59.000Z

    An apparatus for heat treating semiconductor wafers is disclosed. The apparatus includes a heating device which contains an assembly of light energy sources for emitting light energy onto a wafer. In particular, the light energy sources are positioned such that many different radial heating zones are created on a wafer being heated. For instance, in one embodiment, the light energy sources form a spiral configuration. In an alternative embodiment, the light energy sources appear to be randomly dispersed with respect to each other so that no discernable pattern is present. In a third alternative embodiment of the present invention, the light energy sources form concentric rings. Tuning light sources are then placed in between the concentric rings of light.

  9. Diluted magnetic semiconductor nanowires exhibiting magnetoresistance

    DOE Patents [OSTI]

    Yang, Peidong (El Cerrito, CA); Choi, Heonjin (Seoul, KR); Lee, Sangkwon (Daejeon, KR); He, Rongrui (Albany, CA); Zhang, Yanfeng (El Cerrito, CA); Kuykendal, Tevye (Berkeley, CA); Pauzauskie, Peter (Berkeley, CA)

    2011-08-23T23:59:59.000Z

    A method for is disclosed for fabricating diluted magnetic semiconductor (DMS) nanowires by providing a catalyst-coated substrate and subjecting at least a portion of the substrate to a semiconductor, and dopant via chloride-based vapor transport to synthesize the nanowires. Using this novel chloride-based chemical vapor transport process, single crystalline diluted magnetic semiconductor nanowires Ga.sub.1-xMn.sub.xN (x=0.07) were synthesized. The nanowires, which have diameters of .about.10 nm to 100 nm and lengths of up to tens of micrometers, show ferromagnetism with Curie temperature above room temperature, and magnetoresistance up to 250 Kelvin.

  10. Metal aminoboranes

    DOE Patents [OSTI]

    Burrell, Anthony K.; Davis, Benjamin J.; Thorn, David L.; Gordon, John C.; Baker, R. Thomas; Semelsberger, Troy Allen; Tumas, William; Diyabalanage, Himashinie Vichalya; Shrestha, Roshan P.

    2010-05-11T23:59:59.000Z

    Metal aminoboranes of the formula M(NH2BH3)n have been synthesized. Metal aminoboranes are hydrogen storage materials. Metal aminoboranes are also precursors for synthesizing other metal aminoboranes. Metal aminoboranes can be dehydrogenated to form hydrogen and a reaction product. The reaction product can react with hydrogen to form a hydrogen storage material. Metal aminoboranes can be included in a kit.

  11. Helicon wave excitation to produce energetic electrons for manufacturing semiconductors

    DOE Patents [OSTI]

    Molvik, Arthur W. (Livermore, CA); Ellingboe, Albert R. (Fremont, CA)

    1998-01-01T23:59:59.000Z

    A helicon plasma source is controlled by varying the axial magnetic field or rf power controlling the formation of the helicon wave. An energetic electron current is carried on the wave when the magnetic field is 90 G; but there is minimal energetic electron current when the magnetic field is 100 G in one particular plasma source. Similar performance can be expected from other helicon sources by properly adjusting the magnetic field and power to the particular geometry. This control for adjusting the production of energetic electrons can be used in the semiconductor and thin-film manufacture process. By applying energetic electrons to the insulator layer, such as silicon oxide, etching ions are attracted to the insulator layer and bombard the insulator layer at higher energy than areas that have not accumulated the energetic electrons. Thus, silicon and metal layers, which can neutralize the energetic electron currents will etch at a slower or non-existent rate. This procedure is especially advantageous in the multilayer semiconductor manufacturing because trenches can be formed that are in the range of 0.18-0.35 mm or less.

  12. High-efficiency photovoltaics based on semiconductor nanostructures

    SciTech Connect (OSTI)

    Yu, Paul K.L. [University of California, San Diego; Yu, Edward T. [University of Texas at Austin; Wang, Deli [University of California, San Diego

    2011-10-31T23:59:59.000Z

    The objective of this project was to exploit a variety of semiconductor nanostructures, specifically semiconductor quantum wells, quantum dots, and nanowires, to achieve high power conversion efficiency in photovoltaic devices. In a thin-film device geometry, the objectives were to design, fabricate, and characterize quantum-well and quantum-dot solar cells in which scattering from metallic and/or dielectric nanostructures was employed to direct incident photons into lateral, optically confined paths within a thin (~1-3um or less) device structure. Fundamental issues concerning nonequilibrium carrier escape from quantum-confined structures, removal of thin-film devices from an epitaxial growth substrate, and coherent light trapping in thin-film photovoltaic devices were investigated. In a nanowire device geometry, the initial objectives were to engineer vertical nanowire arrays to optimize optical confinement within the nanowires, and to extend this approach to core-shell heterostructures to achieve broadspectrum absorption while maintaining high opencircuit voltages. Subsequent work extended this approach to include fabrication of nanowire photovoltaic structures on low-cost substrates.

  13. Helicon wave excitation to produce energetic electrons for manufacturing semiconductors

    DOE Patents [OSTI]

    Molvik, A.W.; Ellingboe, A.R.

    1998-10-20T23:59:59.000Z

    A helicon plasma source is controlled by varying the axial magnetic field or rf power controlling the formation of the helicon wave. An energetic electron current is carried on the wave when the magnetic field is 90 G; but there is minimal energetic electron current when the magnetic field is 100 G in one particular plasma source. Similar performance can be expected from other helicon sources by properly adjusting the magnetic field and power to the particular geometry. This control for adjusting the production of energetic electrons can be used in the semiconductor and thin-film manufacture process. By applying energetic electrons to the insulator layer, such as silicon oxide, etching ions are attracted to the insulator layer and bombard the insulator layer at higher energy than areas that have not accumulated the energetic electrons. Thus, silicon and metal layers, which can neutralize the energetic electron currents will etch at a slower or non-existent rate. This procedure is especially advantageous in the multilayer semiconductor manufacturing because trenches can be formed that are in the range of 0.18--0.35 mm or less. 16 figs.

  14. Near-Infrared Photoluminescence Enhancement in Ge/CdS and Ge/ZnS Core/Shell Nanocrystals: Utilizing IV/II-VI Semiconductor Epitaxy

    SciTech Connect (OSTI)

    Guo, Yijun [Ames Laboratory; Rowland, Clare E [Argonne National Laboratory; Schaller, Richard D [Argonne National Laboratory; Vela, Javier [Ames Laboratory

    2014-08-26T23:59:59.000Z

    Ge nanocrystals have a large Bohr radius and a small, size-tunable band gap that may engender direct character via strain or doping. Colloidal Ge nanocrystals are particularly interesting in the development of near-infrared materials for applications in bioimaging, telecommunications and energy conversion. Epitaxial growth of a passivating shell is a common strategy employed in the synthesis of highly luminescent II–VI, III–V and IV–VI semiconductor quantum dots. Here, we use relatively unexplored IV/II–VI epitaxy as a way to enhance the photoluminescence and improve the optical stability of colloidal Ge nanocrystals. Selected on the basis of their relatively small lattice mismatch compared with crystalline Ge, we explore the growth of epitaxial CdS and ZnS shells using the successive ion layer adsorption and reaction method. Powder X-ray diffraction and electron microscopy techniques, including energy dispersive X-ray spectroscopy and selected area electron diffraction, clearly show the controllable growth of as many as 20 epitaxial monolayers of CdS atop Ge cores. In contrast, Ge etching and/or replacement by ZnS result in relatively small Ge/ZnS nanocrystals. The presence of an epitaxial II–VI shell greatly enhances the near-infrared photoluminescence and improves the photoluminescence stability of Ge. Ge/II–VI nanocrystals are reproducibly 1–3 orders of magnitude brighter than the brightest Ge cores. Ge/4.9CdS core/shells show the highest photoluminescence quantum yield and longest radiative recombination lifetime. Thiol ligand exchange easily results in near-infrared active, water-soluble Ge/II–VI nanocrystals. We expect this synthetic IV/II–VI epitaxial approach will lead to further studies into the optoelectronic behavior and practical applications of Si and Ge-based nanomaterials.

  15. Spin injection and manipulation in organic semiconductors

    E-Print Network [OSTI]

    Venkataraman, Karthik (Karthik Raman)

    2011-01-01T23:59:59.000Z

    The use of organic semiconductors to enable organic spintronic devices requires the understanding of transport and control of the spin state of the carriers. This thesis deals with the above issue, focusing on the interface ...

  16. Electrical Usage Characterization of Semiconductor Processing Tools

    E-Print Network [OSTI]

    Hinson, S. R.

    This paper presents the basic concepts in performing an energy and power audit of a semiconductor process tool. A protocol exists that fully describes these measurements and their use and applicability and it will be described. This protocol...

  17. Sandia National Laboratories: wide-bandgap semiconductor

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

    electroluminescence was first reported by H.J. Round in 1907, and the first light-emitting diode (LED) was reported by O.V. Losev in 1927. Not until the birth of semiconductor...

  18. NANOSTRUCTURES, MAGNETIC SEMICONDUCTORS AND SPINELECTRONICS Paata Kervalishvili

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    to data storage, switching, lighting and other devices, can lead to substantially new hardwareNANOSTRUCTURES, MAGNETIC SEMICONDUCTORS AND SPINELECTRONICS Paata Kervalishvili Georgian Technical and manipulation on a nanometre scale, which allows the fabrication of nanostructures with the properties mainly

  19. Surface phonons of III-V semiconductors

    E-Print Network [OSTI]

    Das, Pradip Kumar

    1994-01-01T23:59:59.000Z

    are the simplest of all semiconductor surfaces. Their atomic relaxations and electronic surface states are rather well understood. There have, however, been surprisingly few experimental studies of their vibrational properties, and ours in the first detailed...

  20. Semiconductor-nanocrystal/conjugated polymer thin films

    DOE Patents [OSTI]

    Alivisatos, A. Paul (Oakland, CA); Dittmer, Janke J. (Munich, DE); Huynh, Wendy U. (Munich, DE); Milliron, Delia (Berkeley, CA)

    2010-08-17T23:59:59.000Z

    The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

  1. EXCITONIC EIGENSTATES OF DISORDERED SEMICONDUCTOR QUANTUM WIRES

    E-Print Network [OSTI]

    of semiconductors are exploited in solar cells, light emitting diodes, and lasers, and, furthermore, future UNIVERSITY OF MINNESOTA 400 Lind Hall 207 Church Street S.E. Minneapolis, Minnesota 55455­0436 Phone: 612

  2. Nanopatterned Electrically Conductive Films of Semiconductor Nanocrystals

    E-Print Network [OSTI]

    Mentzel, Tamar

    We present the first semiconductor nanocrystal films of nanoscale dimensions that are electrically conductive and crack-free. These films make it possible to study the electrical properties intrinsic to the nanocrystals ...

  3. Fabrication of Semiconductors by Wet Chemical Etch

    E-Print Network [OSTI]

    Francoviglia, Laura

    2008-07-01T23:59:59.000Z

    - ern devices. Beginning with Bardeen, Brittain and Shockley’s invention of the transistor in Bell Labs in 1947 and Kilby and Noyce’s introduction of the integrated circuit about a decade later, semiconductor devices have dramat- ically advanced... ad- dition of impurities, their conductivity can be altered. With the need to manu- facture devices at the micro- and nano- scale, the semiconductor industry has followed “Moore’s Law,” the trend that the number of transistors placed...

  4. Optical temperature indicator using thermochromic semiconductors

    DOE Patents [OSTI]

    Kronberg, J.W.

    1995-01-01T23:59:59.000Z

    A reversible optical temperature indicator utilizes thermochromic semiconductors which vary in color in response to various temperature levels. The thermochromic material is enclosed in an enamel which provides protection and prevents breakdown at higher temperatures. Cadmium sulfide is the preferred semiconductor material. The indicator may be utilized as a sign or in a striped arrangement to clearly provide a warning to a user. The various color responses provide multiple levels of alarm.

  5. A Semiconductor Microlaser for Intracavity Flow Cytometry

    SciTech Connect (OSTI)

    Akhil, O.; Copeland, G.C.; Dunne, J.L.; Gourley, P.L.; Hendricks, J.K.; McDonald, A.E.

    1999-01-20T23:59:59.000Z

    Semiconductor microlasers are attractive components for micro-analysis systems because of their ability to emit coherent intense light from a small aperture. By using a surface-emitting semiconductor geometry, we were able to incorporate fluid flow inside a laser microcavity for the first time. This confers significant advantages for high throughput screening of cells, particulates and fluid analytes in a sensitive microdevice. In this paper we discuss the intracavity microfluidics and present preliminary results with flowing blood and brain cells.

  6. Optical temperature sensor using thermochromic semiconductors

    DOE Patents [OSTI]

    Kronberg, James W. (Aiken, SC)

    1998-01-01T23:59:59.000Z

    An optical temperature measuring device utilizes thermochromic semiconductors which vary in color in response to changes in temperature. The thermochromic material is sealed in a glass matrix which allows the temperature sensor to detect high temperatures without breakdown. Cuprous oxide and cadmium sulfide are among the semiconductor materials which provide the best results. The changes in color may be detected visually using a sensor chip and an accompanying color card.

  7. Optical temperature sensor using thermochromic semiconductors

    DOE Patents [OSTI]

    Kronberg, James W. (108 Independent Blvd., Aiken, SC 29801)

    1996-01-01T23:59:59.000Z

    An optical temperature measuring device utilizes thermochromic semiconductors which vary in color in response to changes in temperature. The thermochromic material is sealed in a glass matrix which allows the temperature sensor to detect high temperatures without breakdown. Cuprous oxide and cadmium sulfide are among the semiconductor materials which provide the best results. The changes in color may be detected visually or by utilizing an optical fiber and an electrical sensing circuit.

  8. Optical devices featuring nonpolar textured semiconductor layers

    DOE Patents [OSTI]

    Moustakas, Theodore D; Moldawer, Adam; Bhattacharyya, Anirban; Abell, Joshua

    2013-11-26T23:59:59.000Z

    A semiconductor emitter, or precursor therefor, has a substrate and one or more textured semiconductor layers deposited onto the substrate in a nonpolar orientation. The textured layers enhance light extraction, and the use of nonpolar orientation greatly enhances internal quantum efficiency compared to conventional devices. Both the internal and external quantum efficiencies of emitters of the invention can be 70-80% or higher. The invention provides highly efficient light emitting diodes suitable for solid state lighting.

  9. Optical temperature indicator using thermochromic semiconductors

    DOE Patents [OSTI]

    Kronberg, James W. (108 Independent Blvd., Aiken, SC 29801)

    1996-01-01T23:59:59.000Z

    A reversible optical temperature indicator utilizes thermochromic semiconductors which vary in color in response to various temperature levels. The thermochromic material is enclosed in an enamel which provides protection and prevents breakdown at higher temperatures. Cadmium sulfide is the preferred semiconductor material. The indicator may be utilized as a sign or in a striped arrangement to clearly provide a warning to a user. The various color responses provide multiple levels of alarm.

  10. Optical temperature sensor using thermochromic semiconductors

    DOE Patents [OSTI]

    Kronberg, J.W.

    1996-08-20T23:59:59.000Z

    An optical temperature measuring device utilizes thermochromic semiconductors which vary in color in response to changes in temperature. The thermochromic material is sealed in a glass matrix which allows the temperature sensor to detect high temperatures without breakdown. Cuprous oxide and cadmium sulfide are among the semiconductor materials which provide the best results. The changes in color may be detected visually or by utilizing an optical fiber and an electrical sensing circuit. 7 figs.

  11. Optical temperature sensor using thermochromic semiconductors

    DOE Patents [OSTI]

    Kronberg, J.W.

    1998-06-30T23:59:59.000Z

    An optical temperature measuring device utilizes thermochromic semiconductors which vary in color in response to changes in temperature. The thermochromic material is sealed in a glass matrix which allows the temperature sensor to detect high temperatures without breakdown. Cuprous oxide and cadmium sulfide are among the semiconductor materials which provide the best results. The changes in color may be detected visually using a sensor chip and an accompanying color card. 8 figs.

  12. Ultrafast Control of Magnetism in Ferromagnetic Semiconductors via Photoexcited Transient Carriers

    E-Print Network [OSTI]

    Cotoros, Ingrid A.

    2009-01-01T23:59:59.000Z

    1.2 Overview of semiconductor2.2 Dilute magnetic semiconductors . . . . . . . . .generated holes in (In,Mn)As Magnetic semiconductor FET

  13. Electron gas grid semiconductor radiation detectors

    DOE Patents [OSTI]

    Lee, Edwin Y. (Livermore, CA); James, Ralph B. (Livermore, CA)

    2002-01-01T23:59:59.000Z

    An electron gas grid semiconductor radiation detector (EGGSRAD) useful for gamma-ray and x-ray spectrometers and imaging systems is described. The radiation detector employs doping of the semiconductor and variation of the semiconductor detector material to form a two-dimensional electron gas, and to allow transistor action within the detector. This radiation detector provides superior energy resolution and radiation detection sensitivity over the conventional semiconductor radiation detector and the "electron-only" semiconductor radiation detectors which utilize a grid electrode near the anode. In a first embodiment, the EGGSRAD incorporates delta-doped layers adjacent the anode which produce an internal free electron grid well to which an external grid electrode can be attached. In a second embodiment, a quantum well is formed between two of the delta-doped layers, and the quantum well forms the internal free electron gas grid to which an external grid electrode can be attached. Two other embodiments which are similar to the first and second embodiment involve a graded bandgap formed by changing the composition of the semiconductor material near the first and last of the delta-doped layers to increase or decrease the conduction band energy adjacent to the delta-doped layers.

  14. Spin Transport in Semiconductor heterostructures

    SciTech Connect (OSTI)

    Domnita Catalina Marinescu

    2011-02-22T23:59:59.000Z

    The focus of the research performed under this grant has been the investigation of spin transport in magnetic semiconductor heterostructures. The interest in these systems is motivated both by their intriguing physical properties, as the physical embodiment of a spin-polarized Fermi liquid, as well as by their potential applications as spintronics devices. In our work we have analyzed several different problems that affect the spin dynamics in single and bi-layer spin-polarized two-dimensional (2D) systems. The topics of interests ranged from the fundamental aspects of the electron-electron interactions, to collective spin and charge density excitations and spin transport in the presence of the spin-orbit coupling. The common denominator of these subjects is the impact at the macroscopic scale of the spin-dependent electron-electron interaction, which plays a much more subtle role than in unpolarized electron systems. Our calculations of several measurable parameters, such as the excitation frequencies of magneto-plasma modes, the spin mass, and the spin transresistivity, propose realistic theoretical estimates of the opposite-spin many-body effects, in particular opposite-spin correlations, that can be directly connected with experimental measurements.

  15. Dissipative chaos in semiconductor superlattices

    SciTech Connect (OSTI)

    Alekseev, K.N.; Berman, G.P. [Center for Nonlinear Studies and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Center for Nonlinear Studies and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); [Kirensky Institute of Physics, 660036, Krasnoyarsk (Russia); [Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080 (United States); Campbell, D.K.; Cannon, E.H.; Cargo, M.C. [Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080 (United States)] [Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080 (United States)

    1996-10-01T23:59:59.000Z

    We consider the motion of ballistic electrons in a miniband of a semiconductor superlattice (SSL) under the influence of an external, time-periodic electric field. We use a semiclassical, balance-equation approach, which incorporates elastic and inelastic scattering (as dissipation) and the self-consistent field generated by the electron motion. The coupling of electrons in the miniband to the self-consistent field produces a cooperative nonlinear oscillatory mode which, when interacting with the oscillatory external field and the intrinsic Bloch-type oscillatory mode, can lead to complicated dynamics, including dissipative chaos. For a range of values of the dissipation parameters we determine the regions in the amplitude-frequency plane of the external field in which chaos can occur. Our results suggest that for terahertz external fields of the amplitudes achieved by present-day free-electron lasers, chaos may be observable in SSL{close_quote}s. We clarify the nature of this interesting nonlinear dynamics in the superlattice{endash}external-field system by exploring analogies to the Dicke model of an ensemble of two-level atoms coupled with a resonant cavity field, and to Josephson junctions. {copyright} {ital 1996 The American Physical Society.}

  16. Thin film reactions on alloy semiconductor substrates

    SciTech Connect (OSTI)

    Olson, D.A.

    1990-11-01T23:59:59.000Z

    The interactions between Pt and In{sub .53}Ga{sub .47}As have been studied. In{sub .53}Ga{sub .47}As substrates with 70nm Pt films were encapsulated in SiO{sub 2}, and annealed up to 600{degree}C in flowing forming gas. The composition and morphology of the reaction product phases were studied using x-ray diffraction, Auger depth profiling, and transmission electron microscopy. The reaction kinetics were examined with Rutherford Backscattering. Results show that Pt/In{sub .53}Ga{sub .47}As reacts to form many of the reaction products encountered in the Pt/GaAs and Pt/InP reactions: PtGa, Pt{sub 3}Ga, and PtAs{sub 2}. In addition, a ternary phase, Pt(In:Ga){sub 2}, develops, which is a solid solution between PtIn{sub 2} and PtGa{sub 2}. The amount of Ga in the ternary phase increases with annealing temperature, which causes a decrease in the lattice parameter of the phase. The reaction products show a tendency to form layered structures, especially for higher temperatures and longer annealing times. Unlike the binary case, the PtAs{sub 2}, phase is randomly oriented on the substrate, and is intermingle with a significant amount of Pt(In:Ga){sub 2}. Following Pt/In{sub .53}Ga{sub .47}As reactions, two orientation relationships between the Pt(In:Ga){sub 2} product phase and the substrate were observed, despite the large mismatch with the substrate ({approximately}8%). For many metal/compound semiconductor interactions, the reaction rate is diffusion limited, i.e. exhibits a parabolic dependence on time. An additional result of this study was the development of an In-rich layer beneath the reacted layer. The Auger depth profile showed a substantial increase in the sample at this layer. This is a significant result for the production of ohmic contacts, as the Schottky barrier height in this system lower for higher In concentrations. 216 refs.

  17. Method for removing semiconductor layers from salt substrates

    DOE Patents [OSTI]

    Shuskus, Alexander J. (West Hartford, CT); Cowher, Melvyn E. (East Brookfield, MA)

    1985-08-27T23:59:59.000Z

    A method is described for removing a CVD semiconductor layer from an alkali halide salt substrate following the deposition of the semiconductor layer. The semiconductor-substrate combination is supported on a material such as tungsten which is readily wet by the molten alkali halide. The temperature of the semiconductor-substrate combination is raised to a temperature greater than the melting temperature of the substrate but less than the temperature of the semiconductor and the substrate is melted and removed from the semiconductor by capillary action of the wettable support.

  18. Metal inks

    DOE Patents [OSTI]

    Ginley, David S; Curtis, Calvin J; Miedaner, Alex; van Hest, Marinus Franciscus Antonius Maria; Kaydanova, Tatiana

    2014-02-04T23:59:59.000Z

    Self-reducing metal inks and systems and methods for producing and using the same are disclosed. In an exemplary embodiment, a method may comprise selecting metal-organic (MO) precursor, selecting a reducing agent, and dissolving the MO precursor and the reducing agent in an organic solvent to produce a metal ink that remains in a liquid phase at room temperature. Metal inks, including self-reducing and fire-through metal inks, are also disclosed, as are various applications of the metal inks.

  19. Extracting hot carriers from photoexcited semiconductor nanocrystals

    SciTech Connect (OSTI)

    Zhu, Xiaoyang

    2014-12-10T23:59:59.000Z

    This research program addresses a fundamental question related to the use of nanomaterials in solar energy -- namely, whether semiconductor nanocrystals (NCs) can help surpass the efficiency limits, the so-called “Shockley-Queisser” limit, in conventional solar cells. In these cells, absorption of photons with energies above the semiconductor bandgap generates “hot” charge carriers that quickly “cool” to the band edges before they can be utilized to do work; this sets the solar cell efficiency at a limit of ~31%. If instead, all of the energy of the hot carriers could be captured, solar-to-electric power conversion efficiencies could be increased, theoretically, to as high as 66%. A potential route to capture this energy is to utilize semiconductor nanocrystals. In these materials, the quasi-continuous conduction and valence bands of the bulk semiconductor become discretized due to confinement of the charge carriers. Consequently, the energy spacing between the electronic levels can be much larger than the highest phonon frequency of the lattice, creating a “phonon bottleneck” wherein hot-carrier relaxation is possible via slower multiphonon emission. For example, hot-electron lifetimes as long as ~1 ns have been observed in NCs grown by molecular beam epitaxy. In colloidal NCs, long lifetimes have been demonstrated through careful design of the nanocrystal interfaces. Due to their ability to slow electronic relaxation, semiconductor NCs can in principle enable extraction of hot carriers before they cool to the band edges, leading to more efficient solar cells.

  20. Light sources based on semiconductor current filaments

    DOE Patents [OSTI]

    Zutavern, Fred J. (Albuquerque, NM); Loubriel, Guillermo M. (Albuquerque, NM); Buttram, Malcolm T. (Sandia Park, NM); Mar, Alan (Albuquerque, NM); Helgeson, Wesley D. (Albuquerque, NM); O'Malley, Martin W. (Edgewood, NM); Hjalmarson, Harold P. (Albuquerque, NM); Baca, Albert G. (Albuquerque, NM); Chow, Weng W. (Cedar Crest, NM); Vawter, G. Allen (Albuquerque, NM)

    2003-01-01T23:59:59.000Z

    The present invention provides a new type of semiconductor light source that can produce a high peak power output and is not injection, e-beam, or optically pumped. The present invention is capable of producing high quality coherent or incoherent optical emission. The present invention is based on current filaments, unlike conventional semiconductor lasers that are based on p-n junctions. The present invention provides a light source formed by an electron-hole plasma inside a current filament. The electron-hole plasma can be several hundred microns in diameter and several centimeters long. A current filament can be initiated optically or with an e-beam, but can be pumped electrically across a large insulating region. A current filament can be produced in high gain photoconductive semiconductor switches. The light source provided by the present invention has a potentially large volume and therefore a potentially large energy per pulse or peak power available from a single (coherent) semiconductor laser. Like other semiconductor lasers, these light sources will emit radiation at the wavelength near the bandgap energy (for GaAs 875 nm or near infra red). Immediate potential applications of the present invention include high energy, short pulse, compact, low cost lasers and other incoherent light sources.

  1. Ge-related faceting and segregation during the growth of metastable (GaAs){sub 1{minus}x}(Ge{sub 2}){sub x} alloy layers by metal{endash}organic vapor-phase epitaxy

    SciTech Connect (OSTI)

    Norman, A.G.; Olson, J.M.; Geisz, J.F.; Moutinho, H.R.; Mason, A.; Al-Jassim, M.M. [National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401 (United States)] [National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401 (United States); Vernon, S.M. [Spire Corporation, One Patriots Park, Bedford, Massachusetts 01730 (United States)] [Spire Corporation, One Patriots Park, Bedford, Massachusetts 01730 (United States)

    1999-03-01T23:59:59.000Z

    (GaAs){sub 1{minus}x}(Ge{sub 2}){sub x} alloy layers, 0{lt}x{lt}0.22, have been grown by metal{endash}organic vapor-phase epitaxy on vicinal (001) GaAs substrates. Transmission electron microscopy revealed pronounced phase separation in these layers, resulting in regions of GaAs-rich zinc-blende and Ge-rich diamond cubic material that appears to lead to substantial band-gap narrowing. For x=0.1 layers, the phase-separated microstructure consisted of intersecting sheets of Ge-rich material on {l_brace}115{r_brace}B planes surrounding cells of GaAs-rich material, with little evidence of antiphase boundaries. Atomic force microscopy revealed {l_brace}115{r_brace}B surface faceting associated with the phase separation. {copyright} {ital 1999 American Institute of Physics.}

  2. Optical spin orientation of a single manganese atom in a semiconductor quantum dot using quasi-resonant excitation

    E-Print Network [OSTI]

    Boyer, Edmond

    of these mem- ories. Dilute magnetic semiconductors (DMS) systems combining semiconductor heterostructures

  3. Effect of contact metals on the piezoelectric properties of aluminum nitride thin films

    SciTech Connect (OSTI)

    Harman, J.P.; Kabulski, A. (West Virginia U., Morgantown, WV); Pagan, V.R. (West Virginia U., Morgantown, WV); Famouri, K. (West Virginia U., Morgantown, WV); Kasarla, K.R.; Rodak, L.E. (West Virginia U., Morgantown, WV); Hensel, J.P.; Korakakis, D.

    2008-07-01T23:59:59.000Z

    The converse piezoelectric response of aluminum nitride evaluated using standard metal insulator semiconductor structures has been found to exhibit a linear dependence on the work function of the metal used as the top electrode. The apparent d33 of the 150–1100 nm films also depends on the dc bias applied to the samples.

  4. DOI: 10.1002/adma.200601787 Microsolidics: Fabrication of Three-Dimensional Metallic

    E-Print Network [OSTI]

    Prentiss, Mara

    in flexible sensors and displays has fueled the development of polymer­metal composites. Re- search in this field includes composites of metal in PDMS with optical functions,[21] conductive PDMS­carbon nanotube oxide semiconductor field-effect transistors,[26] and flexible gold­polymer nano- composites as passive

  5. Semiconductor nanowires for future electronics : growth, characterization, device fabrication, and integration

    E-Print Network [OSTI]

    Dayeh, Shadi A.

    2008-01-01T23:59:59.000Z

    1 1.1 Introduction to Semiconductorin InAs Semiconductor Nanowires. . . . . . . . . . . . .Comparison of different semiconductor NWFETs (non-passivated

  6. Substrate solder barriers for semiconductor epilayer growth

    DOE Patents [OSTI]

    Drummond, T.J.; Ginley, D.S.; Zipperian, T.E.

    1987-10-23T23:59:59.000Z

    During the growth of compound semiconductors by epitaxial processes, substrates are typically mounted to a support. In molecular beam epitaxy, mounting is done using indium as a solder. This method has two drawbacks: the indium reacts with the substrate, and it is difficult to uniformly wet the back of a large diameter substrate. Both of these problems have been successfully overcome by sputter coating the back of the substrate with a thin layer of tungsten carbide or tungsten carbide and gold. In addition to being compatible with the growth of high quality semiconductor epilayers this coating is also inert in all standard substate cleaning etchants used for compound semiconductors, and provides uniform distribution of energy in radiant heating. 1 tab.

  7. Substrate solder barriers for semiconductor epilayer growth

    DOE Patents [OSTI]

    Drummond, Timothy J. (Tijeras, NM); Ginley, David S. (Albuquerque, NM); Zipperian, Thomas E. (Albuquerque, NM)

    1989-01-01T23:59:59.000Z

    During the growth of compound semiconductors by epitaxial processes, substrates are typically mounted to a support. In modular beam epitaxy, mounting is done using indium as a solder. This method has two drawbacks: the indium reacts with the substrate, and it is difficult to uniformly wet the back of a large diameter substrate. Both of these problems have been successfully overcome by sputter coating the back of the substrate with a thin layer of tungsten carbide or tungsten carbide and gold. In addition to being compatible with the growth of high quality semiconductor epilayers this coating is also inert in all standard substrate cleaning etchants used for compound semiconductors, and provides uniform distribution of energy in radiant heating.

  8. Substrate solder barriers for semiconductor epilayer growth

    DOE Patents [OSTI]

    Drummond, T.J.; Ginley, D.S.; Zipperian, T.E.

    1989-05-09T23:59:59.000Z

    During the growth of compound semiconductors by epitaxial processes, substrates are typically mounted to a support. In modular beam epitaxy, mounting is done using indium as a solder. This method has two drawbacks: the indium reacts with the substrate, and it is difficult to uniformly wet the back of a large diameter substrate. Both of these problems have been successfully overcome by sputter coating the back of the substrate with a thin layer of tungsten carbide or tungsten carbide and gold. In addition to being compatible with the growth of high quality semiconductor epilayers this coating is also inert in all standard substrate cleaning etchants used for compound semiconductors, and provides uniform distribution of energy in radiant heating.

  9. Codoped direct-gap semiconductor scintillators

    DOE Patents [OSTI]

    Derenzo, Stephen Edward (Pinole, CA); Bourret-Courchesne, Edith (Berkeley, CA); Weber, Marvin J. (Danville, CA); Klintenberg, Mattias K. (Berkeley, CA)

    2008-07-29T23:59:59.000Z

    Fast, bright inorganic scintillators at room temperature are based on radiative electron-hole recombination in direct-gap semiconductors, e.g. CdS and ZnO. The direct-gap semiconductor is codoped with two different impurity atoms to convert the semiconductor to a fast, high luminosity scintillator. The codopant scheme is based on dopant band to dopant trap recombination. One dopant provides a significant concentration of carriers of one type (electrons or holes) and the other dopant traps carriers of the other type. Examples include CdS:In,Te; CdS:In,Ag; CdS:In,Na; ZnO:Ga,P; ZnO:Ga,N; ZnO:Ga,S; and GaN:Ge,Mg.

  10. Two-Photon Emission from Semiconductors

    E-Print Network [OSTI]

    Alex Hayat; Pavel Ginzburg; Meir Orenstein

    2007-10-25T23:59:59.000Z

    We report the first experimental observations of two-photon emission from semiconductors, to the best of our knowledge, and develop a corresponding theory for the room-temperature process. Spontaneous two-photon emission is demonstrated in optically-pumped bulk GaAs and in electrically-driven GaInP/AlGaInP quantum wells. Singly-stimulated two-photon emission measurements demonstrate the theoretically predicted two-photon optical gain in semiconductors - a necessary ingredient for any realizations of future two-photon semiconductor lasers. Photon-coincidence experiment validates the simultaneity of the electrically-driven GaInP/AlGaInP two-photon emission, limited only by detector's temporal resolution.

  11. Codoped direct-gap semiconductor scintillators

    DOE Patents [OSTI]

    Derenzo, Stephen E.; Bourret-Courchesne, Edith; Weber, Marvin J.; Klintenberg, Mattias K.

    2006-05-23T23:59:59.000Z

    Fast, bright inorganic scintillators at room temperature are based on radiative electron-hole recombination in direct-gap semiconductors, e.g. CdS and ZnO. The direct-gap semiconductor is codoped with two different impurity atoms to convert the semiconductor to a fast, high luminosity scintillator. The codopant scheme is based on dopant band to dopant trap recombination. One dopant provides a significant concentration of carriers of one type (electrons or holes) and the other dopant traps carriers of the other type. Examples include CdS:In,Te; CdS:In,Ag; CdS:In,Na; ZnO:Ga,P; ZnO:Ga,N; ZnO:Ga,S; and GaN:Ge,Mg.

  12. Electroluminescence in ion gel gated organic polymer semiconductor transistors

    E-Print Network [OSTI]

    Bhat, Shrivalli

    2011-07-12T23:59:59.000Z

    This thesis reports the light emission in ion gel gated, thin film organic semiconductor transistors and investigates the light emission mechanism behind these devices. We report that ion gel gated organic polymer semiconductor transistors emit...

  13. Radio frequency identification (RFID) applications in semiconductor manufacturing

    E-Print Network [OSTI]

    Cassett, David Ian, 1971-

    2004-01-01T23:59:59.000Z

    Radio frequency identification (RFID) has an enormous potential impact within the semiconductor supply chain, especially within semiconductor manufacturing. The end benefit of RFID will be in the mass serialization, and ...

  14. A New Cleanroom for a Next-Generation Semiconductor Research...

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

    A New Cleanroom for a Next-Generation Semiconductor Research Tool A New Cleanroom for a Next-Generation Semiconductor Research Tool Print The new Sector 12 cleanroom under...

  15. A study of corporate entrepreneurship in the semiconductor industry

    E-Print Network [OSTI]

    Tallapureddy, Anish R

    2014-01-01T23:59:59.000Z

    The number of semiconductor companies receiving venture funding has been decreasing through-out the last decade. The economics of manufacturing semiconductors do not offer an attractive risk-reward profile to the traditional ...

  16. Course Information --EE 531 Semiconductor Devices and Device Simulation

    E-Print Network [OSTI]

    Hochberg, Michael

    of Semiconductor Devices" by Hess "Si Processing for the VLSI Era: Vol. 3-- The Submicron MOSFET" by Wolf "Advanced: 20% Exam 1: 30% Exam 2: 30% Project: 20% Prerequisite: Semiconductor Devices (EE 482) or equivalent

  17. High-Throughput Transfer Imprinting for Organic Semiconductors

    E-Print Network [OSTI]

    Choo, Gihoon

    2013-08-06T23:59:59.000Z

    semiconductors because heat and pressure used in thermal nanoimprint do not damage functional materials. However, issues such as residual layer removal and mold contamination still limit the application of nanoimprint for organic semiconductor patterning...

  18. Surface passivation process of compound semiconductor material using UV photosulfidation

    DOE Patents [OSTI]

    Ashby, Carol I. H. (Edgewood, NM)

    1995-01-01T23:59:59.000Z

    A method for passivating compound semiconductor surfaces by photolytically disrupting molecular sulfur vapor with ultraviolet radiation to form reactive sulfur which then reacts with and passivates the surface of compound semiconductors.

  19. Acoustoelectric Harmonic Generation in a Photoconductive Piezoelectric Semiconductor

    E-Print Network [OSTI]

    Acoustoelectric Harmonic Generation in a Photoconductive Piezoelectric Semiconductor W. Arthur, R harmonics in the low frequency regime (. Piezoelectric semiconductors can exhibit harmonic generation because of interactions between the acoustic

  20. Silicone metalization

    DOE Patents [OSTI]

    Maghribi, Mariam N. (Livermore, CA); Krulevitch, Peter (Pleasanton, CA); Hamilton, Julie (Tracy, CA)

    2008-12-09T23:59:59.000Z

    A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

  1. Blasting detonators incorporating semiconductor bridge technology

    SciTech Connect (OSTI)

    Bickes, R.W. Jr.

    1994-05-01T23:59:59.000Z

    The enormity of the coal mine and extraction industries in Russia and the obvious need in both Russia and the US for cost savings and enhanced safety in those industries suggests that joint studies and research would be of mutual benefit. The author suggests that mine sites and well platforms in Russia offer an excellent opportunity for the testing of Sandia`s precise time-delay semiconductor bridge detonators, with the potential for commercialization of the detonators for Russian and other world markets by both US and Russian companies. Sandia`s semiconductor bridge is generating interest among the blasting, mining and perforation industries. The semiconductor bridge is approximately 100 microns long, 380 microns wide and 2 microns thick. The input energy required for semiconductor bridge ignition is one-tenth the energy required for conventional bridgewire devices. Because semiconductor bridge processing is compatible with other microcircuit processing, timing and logic circuits can be incorporated onto the chip with the bridge. These circuits can provide for the precise timing demanded for cast effecting blasting. Indeed tests by Martin Marietta and computer studies by Sandia have shown that such precise timing provides for more uniform rock fragmentation, less fly rock, reduce4d ground shock, fewer ground contaminants and less dust. Cost studies have revealed that the use of precisely timed semiconductor bridges can provide a savings of $200,000 per site per year. In addition to Russia`s vast mineral resources, the Russian Mining Institute outside Moscow has had significant programs in rock fragmentation for many years. He anticipated that collaborative studies by the Institute and Sandia`s modellers would be a valuable resource for field studies.

  2. Detection of DNA Hybridization Using the Near-Infrared Band-Gap

    E-Print Network [OSTI]

    Allen, Jont

    shift of 2 meV, with a detection sensitivity of 6 nM. The energy shift is modeled by correlating in the solution- based systems, is advantageous due to the sensitivity and selectivity of the technique.14 absorption of blood and tissue17-19 and the low auto- fluorescence of cells20 in the nIR. Furthermore, SWNTs

  3. PHYSICAL REVIEW B 84, 155438 (2011) Tunable graphene band gaps from superstrate-mediated interactions

    E-Print Network [OSTI]

    Hague, Jim

    2011-01-01T23:59:59.000Z

    , and photovoltaics through the relatively simple application of polarizable materials such as SiO2 and Si3N4. DOI: 10, light-emitting diodes (LEDs), photovoltaics, heterojunctions, and photodetectors. Here, I investigate gap-enhancement effects due to inter- actions mediated through superstrates placed on graphene systems

  4. Alternative Wide-Band-Gap Materials for Gamma-Ray Spectroscopy

    E-Print Network [OSTI]

    He, Zhong

    Engineering and Radiological Sciences) in The University of Michigan 2013 Doctoral Committee: Professor Zhong emotionally, physically, spiritually, and intellectually through every moment of my graduate school career, the Orion group would not be successful without the great work of his graduate students. It has been a truly

  5. Tunable micro-cavities in photonic band-gap yarns and optical fibers

    E-Print Network [OSTI]

    Benoit, Gilles, Ph. D. Massachusetts Institute of Technology

    2006-01-01T23:59:59.000Z

    The vision behind this work is the fabrication of high performance innovative fiber-based optical components over kilometer length-scales. The optical properties of these fibers derive from their multilayer dielectric ...

  6. Partial frequency band gap in one-dimensional magnonic crystals M. Kostylev,1,a

    E-Print Network [OSTI]

    Adeyeye, Adekunle

    approach. It is shown that, due to the one-dimensional artificial periodicity of the medium, the gaps with the artificial spatial periodicity of the structure. In this work, by measuring the frequencies of collective on a silicon substrate using deep ultraviolet lithography with 248 nm exposure wavelength followed by a lift

  7. Novel wide band gap materials for highly efficient thin film tandem solar cells

    SciTech Connect (OSTI)

    Brian E. Hardin, Stephen T. Connor, Craig H. Peters

    2012-06-11T23:59:59.000Z

    Tandem solar cells (TSCs), which use two or more materials to absorb sunlight, have achieved power conversion efficiencies of >25% versus 11-20% for commercialized single junction solar cell modules. The key to widespread commercialization of TSCs is to develop the wide-band, top solar cell that is both cheap to fabricate and has a high open-circuit voltage (i.e. >1V). Previous work in TSCs has generally focused on using expensive processing techniques with slow growth rates resulting in costs that are two orders of magnitude too expensive to be used in conventional solar cell modules. The objective of the PLANT PV proposal was to investigate the feasibility of using Ag(In,Ga)Se2 (AIGS) as the wide-bandgap absorber in the top cell of a thin film tandem solar cell (TSC). Despite being studied by very few in the solar community, AIGS solar cells have achieved one of the highest open-circuit voltages within the chalcogenide material family with a Voc of 949mV when grown with an expensive processing technique (i.e. Molecular Beam Epitaxy). PLANT PV�s goal in Phase I of the DOE SBIR was to 1) develop the chemistry to grow AIGS thin films via solution processing techniques to reduce costs and 2) fabricate new device architectures with high open-circuit voltage to produce full tandem solar cells in Phase II. PLANT PV attempted to translate solution processing chemistries that were successful in producing >12% efficient Cu(In,Ga)Se2 solar cells by replacing copper compounds with silver. The main thrust of the research was to determine if it was possible to make high quality AIGS thin films using solution processing and to fully characterize the materials properties. PLANT PV developed several different types of silver compounds in an attempt to fabricate high quality thin films from solution. We found that silver compounds that were similar to the copper based system did not result in high quality thin films. PLANT PV was able to deposit AIGS thin films using a mixture of solution and physical vapor deposition processing, but these films lacked the p-type doping levels that are required to make decent solar cells. Over the course of the project PLANT PV was able to fabricate efficient CIGS solar cells (8.7%) but could not achieve equivalent performance using AIGS. During the nine-month grant PLANT PV set up a variety of thin film characterization tools (e.g. drive-level capacitance profiling) at the Molecular Foundry, a Department of Energy User Facility, that are now available to both industrial and academic researchers via the grant process. PLANT PV was also able to develop the back end processing of thin film solar cells at Lawrence Berkeley National Labs to achieve 8.7% efficient CIGS solar cells. This processing development will be applied to other types of thin film PV cells at the Lawrence Berkeley National Labs. While PLANT PV was able to study AIGS film growth and optoelectronic properties we concluded that AIGS produced using these methods would have a limited efficiency and would not be commercially feasible. PLANT PV did not apply for the Phase II of this grant.

  8. A Novel Synthesis Method for Designing Electromagnetic Band Gap (EBG) Structures in Packaged Mixed Signal Systems

    E-Print Network [OSTI]

    Swaminathan, Madhavan

    on a periodically patterned power/ground plane. CPA-Method gives a final dimension of EBG structure for a desired. PLM calculates isolation level of an EBG structure based on the transmitted power. The proposed's mixed-signal systems are very sensitive to power/ground noise. For high-speed systems, it has been

  9. Photonic band gap of a graphene-embedded quarter-wave stack

    SciTech Connect (OSTI)

    Fan, Yuancheng [Ames Laboratory; Wei, Zeyong [Tongji University; Li, Hongqiang [Tongji University; Chen, Hong [Tongji University; Soukoulis, Costas M [Ames Laboratory

    2013-12-10T23:59:59.000Z

    Here, we present a mechanism for tailoring the photonic band structure of a quarter-wave stack without changing its physical periods by embedding conductive sheets. Graphene is utilized and studied as a realistic, two-dimensional conductive sheet. In a graphene-embedded quarter-wave stack, the synergic actions of Bragg scattering and graphene conductance contributions open photonic gaps at the center of the reduced Brillouin zone that are nonexistent in conventional quarter-wave stacks. Such photonic gaps show giant, loss-independent density of optical states at the fixed lower-gap edges, of even-multiple characteristic frequency of the quarter-wave stack. The conductive sheet-induced photonic gaps provide a platform for the enhancement of light-matter interactions.

  10. Control of ionization processes in high band gap materials via tailored

    E-Print Network [OSTI]

    Kassel, Universität

    on Ultrafast Electron Dynamics in Femtosecond Optical Breakdown of Dielectrics," Phys. Rev. Lett. 83, 5182­5182

  11. Final Report: Laser-Material Interactions Relevant to Analytic Spectroscopy of Wide Band Gap Materials

    SciTech Connect (OSTI)

    Dickinson, J. T. [Washington State University] [Washington State University

    2014-04-05T23:59:59.000Z

    We summarize our studies aimed at developing an understanding of the underlying physics and chemistry in terms of laser materials interactions relevant to laser-based sampling and chemical analysis of wide bandgap materials. This work focused on the determination of mechanisms for the emission of electrons, ions, atoms, and molecules from laser irradiation of surfaces. We determined the important role of defects on these emissions, the thermal, chemical, and physical interactions responsible for matrix effects and mass-dependent transport/detection. This work supported development of new techniques and technology for the determination of trace elements contained such as nuclear waste materials.

  12. Bispyridinium-phenylene-based copolymers: low band gap n-type alternating copolymers

    E-Print Network [OSTI]

    Swager, Timothy Manning

    Bispyridinium-phenylene-based conjugated donor–acceptor copolymers were synthesized by a Stille cross-coupling and cyclization sequence. These polyelectrolytes are freely soluble in organic solvents and display broad optical ...

  13. Comment on "Direct space-time observation of pulse tunneling in an electromagnetic band gap"

    E-Print Network [OSTI]

    G. Nimtz; A. A. Stahlhofen

    2008-01-13T23:59:59.000Z

    The investigation presented by Doiron, Hache, and Winful [Phys. Rev. A 76, 023823 (2007)] is not valid for the tunneling process as claimed in the paper.

  14. Second harmonic generation from direct band gap quantum dots pumped by femtosecond laser pulses

    SciTech Connect (OSTI)

    Liu, Liwei, E-mail: liulw@cust.edu.cn; Wang, Yue; Hu, Siyi; Ren, Yu; Huang, Chen [School of Science, Changchun University of Science and Technology, Changchun, Jilin 130022, People's Republic of China and International Joint Research Center for Nanophotonics and Biophotonics, Changchun University of Science and Technology, Changchun, Jilin 130022 (China)

    2014-02-21T23:59:59.000Z

    We report on nonlinear optical experiments performed on Cu{sub 2}S quantum dots (QDs) pumped by femtosecond laser pulses. We conduct a theoretical simulation and experiments to determine their second harmonic generation characteristics. Furthermore, we demonstrate that the QDs have a second harmonic generation conversion efficiency of up to 76%. Our studies suggest that these Cu{sub 2}S QDs can be used for solar cells, bioimaging, biosensing, and electric detection.

  15. InAlAs EPITAXIAL GROWTH FOR WIDE BAND GAP SOLAR CELLS Marina S. Leite

    E-Print Network [OSTI]

    Atwater, Harry

    concentrator cells made of metamorphic InGaP/GaAs/InGaAs can achieve > 41 % by using metamorphic epitaxial

  16. Final Report: Tunable Narrow Band Gap Absorbers For Ultra High Efficiency Solar Cells

    SciTech Connect (OSTI)

    Bedair, Salah M. [NCSU; Hauser, John R. [NCSU; Elmasry, Nadia [NCSU; Colter, Peter C. [NCSU; Bradshaw, G. [NCSU; Carlin, C. Z. [NCSU; Samberg, J. [NCSU; Edmonson, Kenneth [Spectrolab

    2012-07-31T23:59:59.000Z

    We report on a joint research program between NCSU and Spectrolab to develop an upright multijunction solar cell structure with a potential efficiency exceeding the current record of 41.6% reported by Spectrolab. The record efficiency Ge/GaAs/InGaP triple junction cell structure is handicapped by the fact that the current generated by the Ge cell is much higher than that of both the middle and top cells. We carried out a modification of the record cell structure that will keep the lattice matched condition and allow better matching of the current generated by each cell. We used the concept of strain balanced strained layer superlattices (SLS), inserted in the i-layer, to reduce the bandgap of the middle cell without violating the desirable lattice matched condition. For the middle GaAs cell, we have demonstrated an n-GaAs/i-(InGaAs/GaAsP)/p-GaAs structure, where the InxGa1-xAs/GaAs1-yPy SLS is grown lattice matched to GaAs and with reduced bandgap from 1.43 eV to 1.2 eV, depending upon the values of x and y.

  17. Nature of the Band Gap and Origin of the Electro-/Photo-Activity...

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

    oxidematerials in photocatalysis and solar applications. Citation: Qiao L, HY Xiao, HM Meyer, JN Sun, CM Rouleau, AA Puretzky, DB Geohegan, IN Ivanov, M Yoon, WJ Weber, and MD...

  18. Semiconductor diode laser having an intracavity spatial phase controller for beam control and switching

    DOE Patents [OSTI]

    Hohimer, John P. (Albuquerque, NM)

    1994-01-01T23:59:59.000Z

    A high-power broad-area semiconductor laser having a intracavity spatial phase controller is disclosed. The integrated intracavity spatial phase controller is easily formed by patterning an electrical contact metallization layer when fabricating the semiconductor laser. This spatial phase controller changes the normally broad far-field emission beam of such a laser into a single-lobed near-diffraction-limited beam at pulsed output powers of over 400 mW. Two operating modes, a thermal and a gain operating mode, exist for the phase controller, allowing for steering and switching the beam as the modes of operation are switched, and the emission beam may be scanned, for example, over a range of 1.4 degrees or switched by 8 degrees. More than one spatial phase controller may be integrated into the laser structure.

  19. Surface plasmon polariton assisted red shift in excitonic emission of semiconductor microflowers

    SciTech Connect (OSTI)

    Parameswaran, Chithra [Centre for Nanotechnology Research, VIT University, Vellore 632014 (India); Warrier, Anita R., E-mail: cvijayan@iitm.ac.in; Bingi, Jayachandra, E-mail: cvijayan@iitm.ac.in; Vijayan, C., E-mail: cvijayan@iitm.ac.in [Indian Institute of Technology Madras, Chennai 600036 (India)

    2014-10-15T23:59:59.000Z

    We report on the study of metal nanoparticle-semiconductor hybrid system composed of ?-indium sulfide (?-In{sub 2}S{sub 3}) and gold (Au) nanoparticles. ?-In{sub 2}S{sub 3} micron sized flower like structures (?1 ?m) and Au nanoparticles (?10 nm) were synthesized by chemical route. These Au nanoparticles have surface plasmon resonance at ? 520 nm. We study the influence of Au surface plasmon polaritons on the radiative properties of the ?-In{sub 2}S{sub 3} microflowers. As a result of the coupling between the surface plasmon polaritons and the excitons there is a red shift ? 50 nm in emission spectrum of hybrid ?-In{sub 2}S{sub 3}-Au system. Such hybrid systems provide scope for a control on the optical properties of semiconductor microstructures, thus rendering them suitable for specific device applications in optoelectronics and photovoltaics.

  20. Semiconductor diode laser having an intracavity spatial phase controller for beam control and switching

    DOE Patents [OSTI]

    Hohimer, J.P.

    1994-06-07T23:59:59.000Z

    A high-power broad-area semiconductor laser having a intracavity spatial phase controller is disclosed. The integrated intracavity spatial phase controller is easily formed by patterning an electrical contact metallization layer when fabricating the semiconductor laser. This spatial phase controller changes the normally broad far-field emission beam of such a laser into a single-lobed near-diffraction-limited beam at pulsed output powers of over 400 mW. Two operating modes, a thermal and a gain operating mode, exist for the phase controller, allowing for steering and switching the beam as the modes of operation are switched, and the emission beam may be scanned, for example, over a range of 1.4 degrees or switched by 8 degrees. More than one spatial phase controller may be integrated into the laser structure. 6 figs.