UScholar Works
 
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CreatorTitleDescriptionSubjectDate
51 Stringfellow, Gerald B.Effects of V/III ratio on ordering and antiphase boundaries in GaInP layersTransmission electron microscope (TEM) and transmission electron diffraction (TED) studies have been performed to investigate the effects of V/III ratio on ordering and antiphase boundaries (APBs) in organometallic vapor phase epitaxial Ga0.5In0.5P layers grown onto (001) GaAs vicinal substrates ...Antiphase boundaries; APB; Heterostructures; Organometallics1997
52 Stringfellow, Gerald B.Effects of V/III ratio on ordering in GaInP: atomic scale mechanismsGa0.5In0.5P layers have been grown by organometallic vapor-phase epitaxy using various values of input V/III ratio for two phosphorus precursors, phosphine, the conventional precursor, and tertiarybutylphosphine (TBP), a newly developed, less-hazardous precursor. For growth on nominally (001) GaAs s...Photoabsorption spectroscopy; Transmission electron diffraction; Phosphorus precursor1996-05-01
53 Scarpulla, MichaelEffects of pressure on the band structure of highly mismatched Zn1-yMnyOxTe1-x alloysWe report photomodulation spectroscopy measurements of the pressure dependence of the optical transition in Zn12yMnyOxTe1-x alloys that is associated with the lowest Ѓ conduction band (termed E2 subband). The pressure-induced energy shift of the E2 transition is nonlinear and much weaker as compare...Highly mismatched alloys; Zinc telluride; Anticrossing2004
54 Scarpulla, MichaelEffects of sodium on electrical properties in Cu2ZnSnS4 single crystalWe have studied the effect of sodium on the electrical properties of Cu2ZnSnS4 (CZTS) single crystal by using temperature dependence of Hall effect measurement. The sodium substitution on the cation site in CZTS is observed from the increasing of unit-cell size by powder X-ray diffraction. Sodium in...2014-01-01
55 Stringfellow, Gerald B.Effects of substrate misorientation and growth rate on ordering in GaInPEpitaxial layers of Ga,Tn,_,P with 1=0.52 have been grown by-organometallic vapor-phase apitaxy on GaAs substrates misoriented from the (001) plane in the [ 1 IO] direction by angles 6,) of O", 3", 6", and 9". For each substrate orientation growth rates rg of 1, 2, and 4 pm/h have been used. The ...Transmission electron diffraction; Dark-field imaging; Photoluminescence1994
56 Stringfellow, Gerald B.Effects of surfactants Sb and Bi on the incorporation of zinc and carbon in III/V materials grown by organometallic vapor-phase epitaxyThe incorporation of both dopants and background impurities during the organometallic vapor phase epitaxial _x0002_OMVPE_x0003_ growth of GaAs, GaInP, and GaP has been significantly altered by the use of the surfactants Sb and Bi. Sb and Bi are isoelectronic with the group V host elements, and so ...Physical and chemical processes; Surfactants isoelectronic; Electrochemical C-V profilometry2006
57 Stringfellow, Gerald B.Electrical properties of nitrogen doped GaPThe electrical properties namely, electron concentration and mobility, have been investigated in the temperature range from 53 to 400 K for undoped and nitrogen-doped VPE GaP.Electron concentration; Ionization energy; Electron mobility1975
58 Tiwari, AshutoshElectrical properties of transparent and conducting Ga doped ZnOIn this paper, we report on the metal-semiconductor transition behavior observed in transparent and conducting ZnO:Ga films grown by pulsed-laser deposition. The electrical resistivity measurements were carried out on ZnO films with varying Ga concentration in the temperature range of 14 to 300 K. ...Transparent conducting oxides; ZnO; Gallium; Metallic conductivity2006
59 Scarpulla, MichaelElectrical transport and ferromagnetism in Ga1−xMnxAs synthesized by ion implantation and pulsed-laser meltingWe present a detailed investigation of the magnetic and magnetotransport properties of thin films of ferromagnetic Ga1−xMnxAs synthesized using ion implantation and pulsed-laser melting (II-PLM). The field and temperature-dependent magnetization, magnetic anisotropy, temperature-dependent resist...GaMnAs; Gallium arsenide2008
60 Tiwari, AshutoshElectrical transport in ZnO1-δ films: transition from band-gap insulator to Anderson localized insulatorWe have thoroughly investigated the effect of oxygen nonstoichiometry on the electrical transport characteristics of ZnO1−δ films. These films were grown on optical grade quartz substrates by using a pulsed laser deposition technique. In order to alter the amount of oxygen nonstoichiometry (δ), ...Anderson localized insulators2004
61 Tiwari, AshutoshElectrical transport in ultrathin NdNiO3 filmsElectrical transport properties in ultrathin NdNiO3 films grown on single crystal LaAlO3 (001) substrate were characterized. Films with thicknesses ranging from 0.6 nm to 12 nm were grown using a pulsed laser technique. Four probe resistivity as a function of temperature measurements indicated a str...2012-01-01
62 Liu, FengElectrochemical measurements on cells, I: Simulation of potential distribution with an embedded probeMeasurements of electric potential in electrochemical devices such as solid oxide fuel cells (SOFC) or solid oxide electrolyzer cells (SOEC) are often made by placing a reference electrode on the surface. Measurement of electric potential with embedded electrodes (probes) has also been reported [1]....2013-01-01
63 Scarpulla, MichaelElectron backscatter diffraction and photoluminescence of sputtered CdTe thin filmsElectron backscatter diffraction (EBSD) has been used to characterize the grain size, grain boundary structure, and texture of sputtered CdTe at varying deposition pressures before and after CdCl2 treatment in order to correlate performance with film microstructure. It is known that twin boundaries ...2011-01-01
64 Stringfellow, Gerald B.Electron mobility in AlxGa1-xAshe electron mobility in AlxGa1-xAs grown by several techniques has been studied to determine whether VPE layers are more highly compensated than comparable LPE layers. The techniques used to grow layers included (1) organometallic VPE using Al(CH3)3, AsH3, and Ga(C2H5)3 or Ga(CH3)3, (2) ''hybrid'' o...Alloys; Organometallics1979-06
65 Stringfellow, Gerald B.Electron mobility in compensated GaAs and AlGaAsThe dependence of electron mobility on temperature in GaAs and Al Ga As indicates that for cimpensated material a term having causes a significant reduction in the mobility measured at high temperatures. The magnitude of the term in mobility, denoted is found to be linearly proportional to the compe...Unspecified mobility; Reduced mobility; Space charge regions1980
66 Tiwari, AshutoshElectron tunneling experiments on La0.7A0.3MnO3 (A=Ca, Sr, Ba)Tunneling conductance measurements of the electronic density of states of perovskite manganates, La0.7A0.3MnO3 are reported. Tunneling data of all the samples show a zero-bias anomaly with a minimum in the density of states at the Fermi level. This behavior is interpreted as arising from strong elec...Perovskite manganates; Tunneling conductance1999-10
67 Liu, FengElectronic and elastic properties of edge dislocations in SiAb initio, tight-binding, and classical calculations have been done for (a/2)( 110) edge dislocation dipoles in Si at separations of 7.5-22.9 A in unit cells comprising 32-288 atoms. These calculations show states associated with the cores relatively deep in the band gap (~ 0.2 eV) despite the abse...Edge dislocations1995-06
68 Liu, FengElectronic strengthening of graphene by charge dopingGraphene is known as the strongest 2D material in nature, yet we show that moderate charge doping of either electrons or holes can further enhance its ideal strength by up to 17%, based on first-principles calculations. This unusual electronic enhancement, versus conventional structural enhancement,...2012-01-01
69 Scarpulla, MichaelEnhanced absorption in optically thin solar cells by scattering from embedded dielectric nanoparticlesAbstract: We present a concept for improving the efficiency of thin-film solar cells via scattering from dielectric particles. The particles are embedded directly within the semiconductor absorber material with sizes on the order of one wavelength. Importantly, this geometry is fully compatible wit...2010
70 Liu, FengEnhanced growth instability of a strained film on wavy substrateWe demonstrate that the growth of a strained film is inherently less stable on a wavy substrate than on a flat substrate. For small surface undulation, the lowest strain energy state is for the film surface to adopt the same wavelength as the substrate surface in an antiphase configuration at the ea...Growth instability; Strained film; Wavy substrate; Strain induced self-assembly2008
71 Scarpulla, MichaelEnhanced light absorption in thin-film silicon solar cells by scattering from Embedded Dielectric NanoparticlesWe investigate the light-trapping effects of dielectric nanoparticles embedded within the active semiconductor layer of a thin-film solar cell. The baseline model consists of a 1.0 μm slab of crystalline silicon on an aluminum back contact topped with a 75 nm Si3N4 anti-reflective coating. Using fi...2011-01-01
72 Scarpulla, MichaelEnhanced nitrogen incorporation by pulsed laser annealing of GaNxAs1-x formed by N ion implantationWe demonstrate that pulsed laser annealing followed by rapid thermal annealing greatly enhances incorporation of substitutional N in N1-implanted GaAs. Films implanted to 1.8% N exhibit a fundamental band gap of 1.26 eV (a band gap reduction of 160 meV), corresponding to an N activation efficiency ...Highly mismatched alloys; Gallium arsenide2002
73 Tiwari, AshutoshEpitaxial growth and properties of MoOx(2We report the growth of epitaxial molybdenum oxide (MoOx,2<x<2.75) films on c plane of sapphire substrate using pulsed laser deposition in oxygen environment. The structure was characterized using x-ray diffraction, high resolution transmission electron microscopy and x-ray photoelectron spectroscop...Epitaxy; MoO2005
74 Tiwari, AshutoshEpitaxial growth and properties of Zn1-xVxO diluted magnetic semiconductor thin filmsHere we report systematic studies on the epitaxial growth and properties of Zn1−xVxO[x=0.001-0.2] thin films deposited onto sapphire c-plane single crystals. The thin films were deposited using pulsed laser deposition technique and were found to be epitaxial in nature. X-ray diffraction and high ...ZnO; Vanadium2005
75 Tiwari, AshutoshEpitaxial growth of TaN films on Si(100) and Si(111) using a TiN buffer layerWe have deposited high-quality epitaxial B1 NaCl-structured TaN films on Si(100) and Si(111) substrates with TiN as the buffer layer, using pulsed laser deposition. Our method exploits the concept of lattice-matching epitaxy between TiN and TaN and domain-matching epitaxy between TiN and silicon. X...Diffusion barriers; Buffer layers; Tantalum nitride; Silicon substrate2002
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