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Filters: Department: "Materials Science & Engineering" Format: "application/pdf" Collection: "ir_uspace" Type: "Text"
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CreatorTitleDescriptionSubjectDate
251 Scarpulla, MichaelSynthesis and properties of highly mismatched II-O-I alloysTernary and quaternary dilute II-VI oxides were synthesised using a highly nonequilibrium method: the combination of O ion implantation and pulsed-laser melting. CdOxTe12x thin films have been produced with x up to 0.015 and with the energy gap reduced by 0.15 eV. Optical transitions corresponding t...Highly mismatched alloys; Cadmium telluride; Zinc telluride; Anticrossing2004
252 Scarpulla, MichaelSynthesis of GaNxAs1-x thin films by pulsed laser melting and rapid thermal annealing of N+-implanted GaAsWe present a systematic investigation on the formation of the highly mismatched alloy GaNxAs1-x using N1-implantation followed by a combination of pulsed laser melting and rapid thermal annealing. Thin films of GaNxAs1-x with x as high as 0.016 and an activation efficiency of the implanted N up to 5...Highly mismatched alloys; Gallium arsenide2003
253 Tiwari, AshutoshTb2O3 thin films: An alternative candidate for high-k dielectric applicationsWe are reporting the growth and structural, optical, and dielectric properties of Tb2O3, a relatively unexplored high-k dielectric material. A pulsed-laser deposition technique was used to grow Tb2O3 thin-films on four different substrates: Si(100), SrTiO3(100), LaAlO3(100), and MgO(100). High resol...2014-01-01
254 Stringfellow, Gerald B.Te doping of GaInP: ordering and step structureThe donor Te has been added to GaInP during organometallic vapor phase epitaxial growth using the precursor diethyltelluride. In agreement with previous studies, the addition of high Te concentrations leads to the elimination of the CuPt ordering observed in undoped layers. The degree of order is es...Epitaxial growth; Heterostructures; Growth parameters1999-04-01
255 Scarpulla, MichaelTe-rich CdTe surface by pulsed UV laser treatment for ohmic back contact formationPulsed UV laser treatments have recently been applied to polycrystalline CdTe solar cells to create an ohmic back contact. In this work, we investigate the surface stoichiometry variations produced by pulsed laser excitation using X-ray photoelectron spectroscopy (XPS). These results reveal surfaces...2014-01-01
256 Scarpulla, MichaelTemperature dependence of equivalent circuit parameters used to analyze admittance spectroscopy and application to CZTSe devicesWe present a device physics and equivalent circuit model for admittance spectroscopy of CZTSe based photovoltaic devices. The experimental variations of the capacitance and conductance in the depletion width are reproduced for state of the art coevaporated CZTSe devices. We will show that simple Arr...2014-01-01
257 Scarpulla, MichaelTemperature dependent conductivity of polycrystalline Cu 2ZnSnS 4 thin filmsThe temperature-dependent conductivity of Cu2ZnSnS4 (CZTS) thin films prepared by sulfurization of different sputtered ZnS/Cu/Sn stacks and also of the same stack annealed for different times was investigated from 30-300 K. Fitting of the through-thickness conductivity requires a model including Mot...2012-01-01
258 Bedrov, Dmitro; Smith, Grant D.Temperature dependent shear viscosity coefficient of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX ): a molecular dynamics simulation studyEquilibrium molecular dynamics methods were used in conjunction with linear response theory and a recently published potential-energy surface [J. Phys. Chem. B 103, 3570 (1999)] to compute the liquid shear viscosity and self-diffusion coefficient of the high explosive HMX (octahydro-1,3,5,7-tetran...Polymer melts; HMX; Shear viscosity coefficient; Plastic-bonded explosives2000
259 Stringfellow, Gerald B.Tertiarybutyldimethylantimony: a new Sb source for low temperature organometallic vapor phase epitaxial growth of InSbThis article investigates tertiarybutyldimethylantimony as a source for low-temperature organometallic vapor phase epitaxial growth of indium antimonide (InSB); extraction of good surface morphology InSb layers; efficiency of InSB growth; and, presence of a negligible parasitic reaction between trim...Tertiarybutyldimethylantimony; Indium antimonide crystals1992
260 Liu, FengTheory of directed nucleation of strained islands on patterned substratesWe develop a theoretical model to elucidate the nucleation of strained islands on patterned substrates. We show that island nucleation is directed to the preferred sites by a much lower energy barrier and smaller critical size. Strain relaxation directs island nucleation to the bottom of a pit rat...Directed nucleation; Strained islands; Patterned substrates2008-11
261 Liu, FengTheory of equilibrium shape of an anisotropically strained island: thermodynamic limits for growth of nanowiresUsing continuum elastic theory, we show that strain anisotropy removes the shape instability existing for an isotropically strained island. An anistropically strained island has always an anisotropic shape, elongating along the less-strained direction and adopting a narrow width in the more-strain...Strained islands; Equilibrium shape; Growth; Thermodynamic limits2004-11
262 Liu, FengTheory of hydrogen pairing in yttriumThe energetics of hydrogen atoms interacting with yttrium have been investigated using the self-consistent cluster model and the local-density approximation. Our results provide a theoretical understanding of a range of novel phenomena observed recently in resistivity, neutron scattering, NMR, and ...Hydrogen pairing; Self-consistent cluster model; Local-density approximation; Energetics1989-09
263 Bedrov, Dmitro; Smith, Grant D.Thermal conductivity of molecular fluids from molecular dynamics simulations: application of a new imposed-flux methodWe have applied a new nonequilibrium molecular dynamics (NEMD) method [F. Müller-Plathe, J. Chem. Phys. 106, 6082 (1997)] previously applied to monatomic Lennard-Jones fluids in the determination of the thermal conductivity of molecular fluids. The method was modified in order to be applicable to...Thermal conductivity; Molecular fluids; Heat flux; Imposed-flux NEMD method2000
264 Liu, FengThermal roughening of a thin film: a new type of roughening transitionThe equilibrium thermal roughening of thin Ge layers (one and two monolayers) deposited on Si(001) has been investigated with low-energy electron microscopy. A Ge-coverage-dependent roughening is observed. For two monolayers, the temperature at which imaging contrast is lost due to surface roughness...Thermal roughening; Roughening transition; Heteroepitaxial growth2000-09
265 Bedrov, Dmitro; Smith, Grant D.Thermodynamic, transport and viscoelastic properties of PBX-9501 binder: a molecular dynamics simulation studyAtomistic molecular dynamics simulations were performed on a low molecular weight nitroplasticized Estane® mixture representative of the binder used in PBX-9501. Pressurevolume-temperature (PVT) behavior over a wide range of pressure and temperatures above the order-disorder temperature (ODT) of Es...PBX-9501 binder; Estane; Viscosity; Shear stress relaxation modulus2008-04-04
266 Chaudhuri, Reaz A.Three-dimensional singular stress field at the front of a crack and lattice crack deviation (LCD) in a cubic single crystal plateA novel eigenfunction expansion technique, based in part on separation of the thickness variable, is developed to derive three-dimensional asymptotic stress fields in the vicinity of the front of a semi-infinite through-crack weakening an infinite plate made of a homogeneous cubic single crystal. C...2010-05-12
267 Liu, FengTopological and electronic transitions in a Sb(111) nanofilm: the interplay between quantum confinement and surface effectWhen the dimension of a solid structure is reduced, there will be two emerging effects, quantum confinement and surface effect, which dominate at nanoscale. Based on first-principles calculations, we demonstrate that due to an intriguing interplay between these two dominating effects, the topologica...2012-01-01
268 Liu, FengTowards quantitative understanding of formation and stability of Ge hut islands on Si(001)We analyze Ge hut island formation on Si(001), using first-principles calculations of energies, stresses, and their strain dependence of Ge/Si(105) and Ge/Si(001) surfaces combined with continuum modeling. We give a quantitative assessment on strain stabilization of Ge(105) facets, estimate the cr...Ge hut islands; Si(001); First-principles calculations; Heteroepitaxial growth2005-05
269 Chaudhuri, Reaz A.Transverse shear stress distribution through thickness near an internal part-through elliptical hole in a stretched plateA semi-analytical post-processing method, termed the equilibrium/compatibility method here, is used for computation of hitherto unavailable through-thickness variation of transverse shear stresses in the vicinity of the circumferential re-entrant corner line of an internal part-through elliptical ...2010-03
270 Liu, FengTuning nucleation density of metal island with charge doping of graphene substrateWe have demonstrated that the island nucleation in the initial stage of epitaxial thin film growth can be tuned by substrate surface charge doping. This charge effect was investigated using spin density functional theory calculation in Fe-deposition on graphene substrate as an example. It was found ...2014-01-01
271 Liu, FengUnderstanding graphene production by ionic surfactant exfoliation: a molecular dynamics simulation studyWe have simulated sodium dodecyl sulfate (SDS) surfactant/waterþbilayer graphene mixture system to investigate two mechanisms of graphene exfoliation: changing the interlayer distance and sliding away the relative distance. By calculating the total energy as a function of the interlayer (sliding-aw...2014-01-01
272 Liu, FengUnique dynamic appearance of a Ge-Si Ad-dimer on Si(001)We carry out a comparative study of the energetics and dynamics of Si-Si, Ge-Ge, and Ge-Si ad-dimers on top of a dimer row in the Si(001) surface, using first-principles calculations. The dynamic appearance of a Ge-Si dimer is distinctively different from that of a Si-Si or Ge-Ge dimer, providing a ...Ge-Si Ad-dimer; Si(001); First-principles calculations; Energetics2000-12
273 Stringfellow, Gerald B.Use of Nitrogen to disorder GaInPSignificant changes in microstructure, surface structure, and alloy composition have been observed in GaInP with the addition of nitrogen. These effects occur due to surface changes induced by small concentrations of nitrogen. Transmission electron microscopy and photoluminescence experiments indica...Nitrogen; Alloys; Transmission2004
274 Stringfellow, Gerald B.; Shurtleff, James KevinUse of surfactant Sb to induce triple period ordering in GaInPA surfactant is used to induce an ordered structure in an epitaxial layer. The addition of small amounts of triethylantimony during the organometallic vapor phase epitaxy growth of GaInP on 001 GaAs substrates is shown to remove CuPt ordering with a resultant increase in band gap energy. Increasi...Organometallic; Thermodynamics; Surfactant2000-03-13
275 Tiwari, AshutoshZn0.9Co0.1O-based diluted magnetic semiconducting thin filmsHere we report a systematic study of structural, optical, and magnetic measurements on epitaxial Zn0.9Co0.1O films grown on c-plane sapphire single crystal, at various temperatures (500-650°C), using pulsed-laser deposition. The main emphasis in this work has been on the correlation of microstructu...ZnO; Cobalt2004
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