UScholar Works
 
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CreatorTitleDescriptionSubjectDate
176 Liu, FengNature of reactive O2 and slow CO2 evolution kinetics in CO oxidation by TiO2 supported Au clusterRecent experiments on CO oxidation reaction using seven-atom Au clusters deposited on TiO2 surface correlate CO2 formation with oxygen associated with Au clusters. We perform first principles calculations using a seven-atom Au cluster supported on a reduced TiO2 surface to explore potential candidat...Au clusters; TiO2; Kinetic evolution2006
177 Scarpulla, MichaelNear-infrared absorption and semimetal-semiconductor transition in 2 nm ErAs nanoparticles embedded in GaAs and AlAsWe report strong near-infrared absorption peaks in epitaxial films of GaAs and AlAs containing approximately 0.5-5% of the semimetal ErAs. The energy of the resonant absorption peak can be changed from 0.62 to 1.0 eV (2.2-1.4 μm) by variation of the ErAs volume fraction and the substrate temperatu...Near-infrared absorption; Semimetal-semiconductor transition; GaAs; AlAs; ErAs; Gallium arsenide; Aluminum arsenide2008
178 Scarpulla, MichaelNew methodologies for measuring film thickness, coverage, and topographyWe describe how the techniques of X-ray reflectivity (XRR), electron spectroscopy for chemical analysis (ESCA), and atomic force microscopy (AFM) can be used to obtain the structural parameters-thickness, coverage, and topography-of thin films used on magnetic recording disks. We focus on ultra-thi...Atomic force microscopy; Electron spectroscopy for chemical analysis; X-ray reflectivity2000-01
179 Stringfellow, Gerald B.Nitrogen surfactant effects in GaInPThe addition of surfactant nitrogen during the growth of GaInP on 001 GaAs substrates produces significant and interesting changes in the optical and morphological properties of GaInP. In particular, multiple peaks are seen in the low temperature photoluminescence (PL) spectra of GaInP/GaInP:N he...Surfactant nitrogen; Microscopy; Crystals2004
180 Smith, Grant D.; Bedrov, DmitroNMR experiments and molecular dynamics simulations of the segmental dynamics of polystyreneWe have performed NMR spin?lattice relaxation experiments and molecular dynamics (MD) computer simulations on atactic polystyrene (a-PS). The segmental correlation times of three different molecular weight a-PS (Mn = 1600, 2100, 10 900 g/mol) were extracted from NMR by measuring the 2H spin?lattice ...2004
181 Scarpulla, MichaelNonmagnetic compensation in ferromagnetic Ga1-xMnxAs and Ga1-xMnxP synthesized by ion implantation and pulsed-laser meltingThe electronic and magnetic effects of intentional compensation with nonmagnetic donors are investigated in the ferromagnetic semiconductors Ga1−xMnxAs and Ga1−xMnxP synthesized using ion implantation and pulsed-laser melting. It is demonstrated that compensation with nonmagnetic donors and MnI ...Ferromagnetic semiconductors2008
182 Tiwari, AshutoshObservation of the inverse spin hall effect in ZnO thin films: an all-electrical approach to spin injection and detectionThe inverse spin Hall effect (ISHE) is a newly discovered, quantum mechanical phenomenon where an applied spin current results in the generation of an electrical voltage in the transverse direction. It is anticipated that the ISHE can provide a more simple way of measuring spin currents in spintroni...2014-01-01
183 Shetty, Dinesh K.On the effect of birefringence on light transmission in Polycrystalline Magnesium FluorideLight transmission in polycrystalline magnesium fluoride was studied as a function of the mean grain size at different wavelengths. The mean grain size was varied by annealing hot-pressed billets in argon atmosphere at temperatures ranging from 600 to 800°C for 1 hour. The grain-size and grain-orie...2014-01-01
184 Smith, Grant D.On the non-Gaussianity of chain motion in unentangled polymer meltsWe have investigated chain dynamics of an unentangled polybutadiene melt via molecular dynamics simulations and neutron spin echo experiments. Good short-time statistics allows for the first experimental confirmation of subdiffusive motion of polymer chains for times less than the Rouse time (T R) c...Polymer melts; Chain dynamics; 1,4-polybutadiene melts; Neutron spin echo2001
185 Chaudhuri, Reaz A.On three-dimensional singular stress/residual stress fields at the front of a crack/anticrack in an orthotropic/orthorhombic plate under anti-plane shear loadingA novel eigenfunction expansion technique, based in part on separation of the thickness-variable, is developed to derive three-dimensional asymptotic stress field in the vicinity of the front of a semi-infinite through-thickness crack/anticrack weakening/reinforcing an infinite orthotropic/orthorhom...2010-07
186 Liu, FengOrbit- and atom-resolved spin textures of intrinsic, extrinsic, and hybridized Dirac cone statesCombining first-principles calculations and spin- and angle-resolved photoemission spectroscopy measurements, we identify the helical spin textures for three different Dirac cone states in the interfaced systems of a two-dimensional (2D) topological insulator (TI) of a Bi(111) bilayer and a three-di...2014-01-01
187 Stringfellow, Gerald B.Organometallic vapor phase epitaxial growth of AlGaInPAlx Ga,, In, _ x _ y P with x + y = 0.51, lattice matched to the GaAs substrate, has been grown by organometaUic vapor phase epitaxy. The simple, horizontal, IR heated system operates at atmospheric pressure using the reactants TMA1, TMGa, TMln, PH3, and K2. Alloys giving room temperature, band edge...Liquid phase epitaxial growth; LPE; Alloys; Surface morphology1985
188 Stringfellow, Gerald B.; Cohen, Richard M.Organometallic vapor phase epitaxial growth of high purity GaInAs using trimethylindiumGax In1−xAs lattice matched to the InP substrate (x=0.47) has been grown by organometallic vapor phase epitaxy using trimethylindium (TMIn) and trimethylgallium (TMGa) as the group III sources and AsH3 as the As source. In a simple, horizontal, atmospheric pressure reactor, the GaInAs growth proce...Electron mobilities; Photouminescience; Fabricate modulation1984-03-01
189 Liu, FengOrigin of intergranular embrittlement of Al alloys induced by Na and Ca segregation: grain boundary weakeningUsing a first-principles computational tensile test, we show that the ideal tensile strength of an Al grain boundary (GB) is reduced with both Na and Ca GB segregation. We demonstrate that the fracture occurs in the GB interface, dominated by the break of the interfacial bonds. Experimentally, we f...Intergranular embrittlement; Grain boundary; Intergranular fracture2006-06
190 Tiwari, AshutoshOxides for spintronics: a review of engineered materials for spin injectionIn this article we have reviewed the role of oxides in spintronics research, and specifically how these materials stand to further improve the efficiencies and capabilities of spin injection for active spintronic device development. The use of oxides in spintronics is advantageous in that they are s...2014-01-01
191 Liu, FengPattern formation on silicon-on-insulatorThe strain driven self-assembly of faceted Ge nanocrystals during epitaxy on Si(001) to form quantum dots (QDs) is by now well known. We have also recently provided an understanding of the thermodynamic driving force for directed assembly of QDs on bulk Si (extendable to other QD systems) based on ...Pattern formation; Silicon-on-insulator; Strain driven; Faceted Ge nanocrystals; Si(001); Directed assembly2005
192 Liu, FengPattern formation via a two-step faceting transition on vicinal Si(111) surfacesWe demonstrate a self-organized pattern formation on vicinal Si(l 11) surfaces that are miscut toward the [211] direction. All the patterns, consisting of a periodic array of alternating (7x7) reconstructed terraces and step-bunched facets, have the same periodicity and facet structure, independent ...Pattern formation; Faceting transition; Vicinal Si(111); Miscut2001
193 Stringfellow, Gerald B.Photoluminescence of Shallow Acceptors in Epitaxial AlGaAsThe low-temperature (2 K) photoluminescence (PL) of AlxGa1-xAs (0<x<0.25 was studied in an effort to characterize shallow acceptors in material grown by organometallic vapor phase epitaxy and liquid phase epitaxy techniques. The dominant shallow acceptor in nominally undoped AlxGa1-xAs specimens gro...Photoluminescence; Acceptors; Doping1980
194 Liu, FengPhysical origin of hydrogen-adsorption-induced metallization of the SiC surface: n-type doping via formation of hydrogen bridge bondWe perform first-principles calculations to explore the physical origin of hydrogen-induced semiconductor surface metallization observed in β-SiC(001)-3 x 2 surface. We show that the surface metallization arises from a novel mechanism of n-type doping of surface band via formation of hydrogen bri...Metallization; Hydrogen adsorption; SiC; n-type doping; Hydrogen bridge bond2005-10
195 Borodin, Oleg; Smith, Grant D.; Bedrov, DmitroPolarizable and nonpolarizable force fields for alkyl nitratesQuantum-chemistry-based many-body polarizable and two-body nonpolarizable atomic force fields were developed for alkyl nitrate liquids and pentaerythritol tetranitrate (PETN) crystal. Bonding, bending, and torsional parameters, partial charges, and atomic polarizabilities for the polarizable force f...Alkyl nitrate; Pentaerythritol tetranitrate; PETN; Polarizable atomic force fields; Nonpolarizable atomic force fields2007
196 Liu, FengPrediction of a Dirac state in monolayer TiB2We predict the existence of a Dirac state in a monolayer TiB2 sheet (m-TiB2), a two-dimensionalmetal diboride, based on first-principles calculations. The band structure of m-TiB2 is found to be characterized with anisotropic Dirac cones with the largest Fermi velocity of 0.57 × 106 m/s, which is a...2014-01-01
197 Smith, Grant D.Prediction of the linear viscoelastic shear modulus of an entangled polybutadiene melt from simulation and theoryWhile accurate quantum chemistry based potentials,1 improved simulation algorithms, and faster computers have made accurate calculation of chain dynamics in unentangled polymer melts from molecular dynamics simulations possible,2-5 direct calculation of the viscoelastic properties of entangled polym...Polybutadiene melt; Viscoelastic shear; Chain dynamics; Entangled polymers2000
198 Liu, FengPressure-induced hard-to-soft transition of a single carbon nanotubeWe demonstrate a hydrostatic pressure-induced hard-to-soft transition of an isolated single wall carbon nanotube, using classical and ab initio constant-pressure molecular-dynamics simulations and continuum elastic theory analysis. At low pressure, the carbon tube is hard. Above a critical pressur...Carbon nanotubes; Hard-to-soft transition2004-10
199 Liu, FengPressure-induced transition in magnetoresistance of single-walled carbon nanotubesWe applied hydrostatic pressure (up to 10 GPa) to single-walled carbon nanotube bundles at low temperature (down to 2 K) to measure their magnetoresistance (MR) in a field up to 12 T. We found a pressure-induced transition in MR from positive to negative in the high-field regime. The onset of the tr...Single-walled carbon nanotubes; Pressure-induced2006-07
200 Scarpulla, MichaelProbing semiconductor band structures and heterojunction interface properties with ballistic carrier emission: GaAs/AlxGa1-xAs as a model systemUtilizing three-terminal tunnel emission of ballistic electrons and holes in a planar tunnel transistor with a Mott-barrier collector, we have developed a method to self-consistently determine the energy gap of a semiconductor and band discontinuities at a semiconductor heterojunction without using...2010-06
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