UScholar Works
 
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CreatorTitleDescriptionSubjectDate
76 Bedrov, Dmitro; Smith, Grant D.Anomalous pressure dependence of the structure factor in 1,4-polybutadiene melts: a molecular dynamics simulation studyNeutron scattering has shown the first diffraction peak in the structure factor of a 1,4-polybutadiene melt under compression to move to larger q values as expected but to decrease significantly in intensity. Simulations reveal that this behavior does not result from loss of structure in the polymer...Polymer melts; 1, 4-polybutadiene melts; Pressure; Structure factor2004-07
77 Smith, Grant D.; Borodin, OlegMolecular-dynamics simulation study of dielectric relaxation in a 1,4-polybutadiene meltWe have carried out atomistic molecular dynamics simulations of a melt of 1,4-poly(butadiene) from temperatures well above the experimentally observed merging of the primary a process and secondary b process down to temperatures approaching the experimentally observed bifurcation temperature. The re...Polymer melts; 1,4-polybutadiene; Chain dynamics; Conformational dynamics2002
78 Stringfellow, Gerald B.Miscibility gaps and spinodal decomposition in III/V quaternary alloys of the type AxByC1−x−yDThermodynamic concepts have been developed for the calculation of solid-phase miscibility gaps and spinodal decomposition in quaternary alloys of the type AxByC1−x−yD. These concepts have been applied to the analysis of III/V quaternary alloys using the delta-lattice-parameter (DLP) solution mod...Thermodynamics; Quartenary alloys; Coherent decomposition1983-01
79 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
80 Liu, FengComputational designing of carbon nanotube electromechanical pressure sensorsWe investigate electronic transport properties of single-walled carbon nanotubes (SWNT's) under hydrostatic pressure, using first-principles quantum transport calculations aided by molecular-dynamics simulation and continuum mechanics analysis. We demonstrate a pressure-induced metal-to-semiconduc...Carbon nanotubes; Computational designing; Pressure sensors; Electronic transport2004-04
81 Liu, FengLiu et al. replyIn our paper we were alluding to a structural phase transition rather than an order-disorder one. We agree with Blaschko2 that more work needs to be done regarding the statistical mechanics of the hydrogen ordering. This was already acknowledged in our paper when we stated that the model of nonint...Structural phase transition; Hydrogen ordering; Ising lattice-gas models; Proton glass1990
82 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
83 Stringfellow, Gerald B.InAsSbBi alloys grown by organometallic vapor-phase epitaxyProvides information on a study on the growth of InAsSbBi alloys by organometallic vapor-phase epitaxy. Experiment; Results and discussion; Conclusion.Alloys; Epitaxy; Organometallic Compounds1994
84 Stringfellow, Gerald B.Spectroscopic study of surfactant enhanced organometallic vapor phase epitaxy growth of GaInPSamplen s of GaxIn1-xP grown by organometallic vapor phase epitaxy on (001) GaAs substrates by addition of TESb demonstrating a lateral superlattice compositional modulation (CM) have been studied by low temperature polarized photoluminescence (PL), power dependent PL, and photoluminescence excitati...Organometallic vapor; Photoluminescence excitation; Spectroscopy2001
85 Liu, FengMechanism for nanotube formation from self-bending nanofilms driven by atomic-scale surface-stress imbalanceWe demonstrate, by theoretical analysis and molecular dynamics simulation, a mechanism for fabricating nanotubes by self-bending of nanofilms under intrinsic surface-stress imbalance due to surface reconstruction. A freestanding Si nanofilm may spontaneously bend itself into a nanotube without exter...Nanotube formation; Self-bending nanofilms; Surface-stress imbalance2007-04
86 Scarpulla, MichaelBandgap and band offsets determination of semiconductor heterostructures using three-terminal ballistic carrier spectroscopyAmong the most important properties of semiconductors are their bandgaps and how the total bandgap difference distributes between the conduction band offset ΔEC and the valence band offset ΔEV at the heterojunction (HJ) interface between two semiconductors. Understanding such properties is crucial...Bandgaps; Band offsets; Gallium arsenide2009
87 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
88 Liu, FengBending of nanoscale ultrathin substrates by growth of strained thin films and islandsMechanical bending is ubiquitous in heteroepitaxial growth of thin films where the strained growing film applies effectively an "external" stress to bend the substrate. Conventionally, when the deposited film is much thinner than the substrate, the bending increases linearly with increasing film th...Nanoscale ultrathin substrates; Strained thin films; Islands; Heteroepitaxial growth; Si substrate; Ge film2005-08
89 Liu, FengSurface mobility difference between Si and Ge and its effect on growth of SiGe alloy films and islandsBased on first-principles calculations of surface diffusion barriers, we show that on a compressive Ge(001) surface the diffusivity of Ge is 102-103 times higher than that of Si in the temperature range of 300 to 900 K, while on a tensile surface, the two diffusivities are comparable. Consequently, ...Surface mobility; SiGe film; Strained thin films; Surface diffusion barriers2006-01
90 Tiwari, AshutoshEpitaxial growth of magnetic nickel nanodots by pulsed laser depositionEpitaxial nickel magnetic nanodots were obtained by pulsed laser deposition (PLD) technique on Si (100) substrate using epitaxial TiN film as the template. Characterization methods include: high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM) Z-...Nanodots; TiN; Nickel2003
91 Stringfellow, Gerald B.Influence of tellurium doping on step bunching of GaAs (001) vicinal surfaces grown by organometallic vapor phase epitaxyAtomic force microscopy has been used to investigate the influence of controlled tellurium Te incorporation on the step structure of GaAs grown by organometallic vapor phase epitaxy on vicinal 001 surfaces. Te doping, using the precursor diethyltelluride, is found to markedly decrease the surface r...Epitaxial growth; Misorientation; Organometallic vapor phase epitaxy1998
92 Stringfellow, Gerald B.Long wavelength lattice dynamics for quaternary alloys: GaInPSb and AlGaAsSbPresents information on a study which investigated the long wavelength lattice dynamics of quaternary alloys. Theory of the random cell isodisplacement model; Secular equation developed; Results and discussion.Lattice dynamics; Quaternary alloys1992
93 Stringfellow, Gerald B.; Shurtleff, James KevinAdsorption and desorption of the surfactant Sb on GaInP grown by organometallic vapor phase epitaxyIt has been determined that ordering has a profound effect on the bandgap energy of many compound semiconductor alloys. Therefore, ordering must be controlled for devices such as solar cells, light emitting diodes and diode lasers. Since ordering depends on the surface properties during organomet...Time dependent surface photoabsorption (SPA); Compound semiconductor alloys2000
94 Liu, FengSelf-assembly of two-dimensional islands via strain-mediated coarseningWe demonstrate two distinctive effects of strain-induced island-island interaction on island size and spatial distribution during coarsening of 2D islands. When coarsening proceeds via only mass transport between islands, the interaction broadens the island size distribution, leading to a power-law...Two-dimensional islands; Strain-mediated coarsening2001-08
95 Tiwari, AshutoshCopper diffusion characteristics in single-crystal and polycrystalline TaNWe have investigated the diffusivity of copper in single-crystal (NaCl-structured) and polycrystalline TaN thin films grown by pulsed-laser deposition. Polycrystalline TaN films were grown directly on Si(100), while single-crystal films were grown with TiN buffer layers. Both poly- and single-crysta...Diffusion barriers; Copper diffusion; Tantalum nitride2002
96 Liu, FengStrain effect on adatom binding and diffusion in homo- and heteroepitaxies of Si and Ge on (001) SurfacesStrain dependence of adatom binding energies and diffusion barriers in homo- and heteroepitaxies of Si and Ge on s001d surface has been studied using first-principles calculations. In general, Si adatom binding energies and diffusion barriers are larger on Sis001d and Ges001d surfaces than a Ge ada...Strain effect; Adatom binding; Adatom diffusion; Adatoms; Heteroepitaxies; Homoepitaxies; (001) surfaces; Si; Ge2004-10
97 Liu, FengStep-induced magnetic-hysteresis anisotropy in ferromagnetic thin filmsWe investigate the quasistatic magnetic hysteresis of ferromagnetic thin films grown on a vicinal substrate, using Monte Carlo simulations within a two-dimensional XY model. Intrinsic in-plane anisotropy is assigned to surface sites according to their local symmetry. The simulated hysteresis loops s...Magnetic hysteresis; Ferromagnetic thin films; Step-induced2002
98 Tiwari, AshutoshGrowth of epitaxial ZnO films on Si(111)Epitaxial ZnO films have been grown on Si(l 11) substrates by employing a A1N buffer layer during a pulsed laser-deposition process. The epitaxial structure of A1N on Si(l 11) substrate provides a template for ZnO growth. The resultant films are evaluated by transmission electron microscopy, x-ray ...Buffer layers; Aluminum nitride; Silicon substrate2002
99 Scarpulla, MichaelDiluted II-VI oxide semiconductors with multiple band gapsWe report the realization of a new mult-band-gap semiconductor. Zn1-yMnyOxTe1-x alloys have been synthesized using the combination of oxygen ion implantation and pulsed laser melting. Incorporation of small quantities of isovalent oxygen leads to the formation of a narrow, oxygen-derived band of ...Highly mismatched alloys; Zinc telluride2003-12
100 Stringfellow, Gerald B.Surface photoabsorption study of the effects of growth temperature and V/III ratio on ordering in GaInPSurface photoabsorption (SPA) measurements were used to clarify the Cu-Pt ordering mechanism in Ga0.5In0.5P layers grown by organometallic vapor phase epitaxy. The Cu-Pt ordering is strongly affected by the growth temperature and the input partial pressure of the phosphorus precursor, i.e., the V/II...P-dimer concentration; Oriented phosphorus dimers; Surface reconstruction1996-05-01
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