UScholar Works
 
Filters: Department: "Materials Science & Engineering" School Or College: "College of Engineering" Collection: "ir_uspace"
101 - 125 of 288
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CreatorTitleDescriptionSubjectDate
101 Pugmire, Ronald J.Investigation of the structural conformation of biphenyl by solid state 13C NMR and quantum chemical NMR shift calculationsThe principal values of the 13C chemical-shift tensor (CST) for biphenyl have been determined with the FIREMAT experiment. The internal dihedral angle between the benzene rings in biphenyl is estimated to fall between 10 and 20° on the basis of quantum mechanical calculations of the CST principal v...Carbon-13; Chemical-shift tensor; biphenyl; FIREMAT2001
102 Bedrov, Dmitro; Smith, Grant D.Exploration of conformational phase space in polymer melts: a comparison of parallel tempering and conventional molecular dynamics simulationsParallel tempering molecular dynamics simulations have been performed for 1,4-polybutadiene polymer melts in the 323 K-473 K temperature domain at atmospheric pressure. The parallel tempering approach provides a vast improvement in the equilibration and sampling of conformational phase space for ...Polymer melts; 1,4-polybutadiene; Conformational phase space; Parallel tempering2001
103 Stringfellow, Gerald B.; Shurtleff, James KevinSurfactant effects on doping of GaAs grown by organometallic vapor phase epitaxyRecently, the addition of the isoelectronic surfactant Sb during organometallic vapor phase epitaxy (OMVPE) of GaInP was shown to eliminate ordering, resulting in a significant change in the band gap energy. These results suggest that surfactants added during growth could have profound affects on ot...Gallium arsenide; Surfactants; Semiconductors2001
104 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
105 Liu, FengSimple generic method for predicting the effect of strain on surface diffusionWe show, by first-principles calculations, that the effect of external strain on surface diffusion is inherently correlated with the intrinsic surface stress induced by the adatom along its diffusion pathways. We demonstrate a simple generic method for a priori predicting quantitatively how an ext...Surface diffusion; First-principles calculations; Adatoms2001-11
106 Liu, FengSurface stress-induced island shape transition in Si(001) homoepitaxyA low-energy electron microscopy study of two-dimensional Si(001) island shapes near thermal equilibrium on 10315 mm2 large single-domain terraces reveals a continuous increase of island aspect ratio and a shape transition from elliptical to ‘‘American-football''-like with increasing island size...Si(001); Homoepitaxy; Island shape transition; Single-domain terraces2001-11
107 Bedrov, Dmitro; Smith, Grant D.Molecular dynamics simulations of HMX crystal polymorphs using a flexible molecule force fieldMolecular dynamics simulations using a recently developed quantum chemistry-based atomistic force field [J. Phys. Chem. B 103 (1999) 3570] were performed in order to obtain unit cell parameters, coefficients of thermal expansion, and heats of sublimation for the three pure crystal polymorphs of octa...HMX; Crystal polymorphs; Force field; Coefficients of thermal expansion; Heat of sublimation; Cell parameters2002
108 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
109 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
110 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
111 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
112 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
113 Tiwari, AshutoshSingle crystal TaN thin films on TiN/Si heterostructureWe have successfully grown epitaxial cubic (Bl-NaCl structure) tantalum nitride films on Si (100) and (111) substrate using a pulsed laser deposition technique. A thin layer of titanium nitride was used as a buffer medium. We characterized these films using X-ray diffraction, high resolution transmi...Tantalum nitride; Diffusion barriers; Copper diffusion2002
114 Tiwari, AshutoshStress-induced tuning of metal-insulator transition in NdNiO3 filmsWe have used the lattice-mismatch epitaxial strain, induced by the constraint of epitaxy, to tune the metal-insulator (M- I) transition temperature of NdNiO3 films grown on Si(100) substrate. Films were integrated with the Si(100) substrate using several combinations of thin buffer layers. A system...NdNiO3; Silicon substrate; Tantalum nitride; Buffer layers; Biaxial strain2002
115 Tiwari, AshutoshGrowth of epitaxial NdNiO3 and integration with Si(100)We have grown epitaxial NdNiO3 films on Si(100) substrate under ambient oxygen pressure using a pulsed-laser deposition method. The integration of NdNiO3 with Si(100) was accomplished by lattice-matching epitaxy of MgO and SrTiO3 and domain matching epitaxy of TiN on Si(100). During domain matching...NdNiO3; SrTiO3; Silicon substrate2002
116 Bedrov, Dmitro; Smith, Grant D.Comparison of self-assembly in lattice and off-lattice model amphiphile solutionsLattice Monte Carlo and off-lattice molecular dynamics simulations of h1t4 and h4t1 (head/tail) amphiphile solutions have been performed as a function of surfactant concentration and temperature. The lattice and off-lattice systems exhibit quite different self-assembly behavior at equivalent ther...Amphiphile solutions; Micellization; Surfactants2002
117 Tiwari, AshutoshSelf-aligned passivated copper interconnects: a novel technique for making interconnections in ultra large scale integration device applicationsWe have developed a technique to grow self-aligned epitaxial Cu/MgO films on Si (100) using a Pulsed Laser Deposition Method. In this method we deposit a uniform film of Cu/Mg (5-7%) alloy over Si (100) at room temperature using TiN as an intermediate buffer layer. As a result of HRTEM (with spatial...Passivated copper interconnects; Diffusion barriers; Copper diffusion; Tantalum nitride2002
118 Stringfellow, Gerald B.Influence of Sb, Bi, Tl, and B on the incorporation of N in GaAsGaAs:N is an interesting material for many devices due to its unique compositional variation of band gap. Small amounts of N lead to a strong decrease in band gap energy as well as lattice constant. The further addition of In or Sb leads to quaternary alloys with band gap energies below 1.4 eV latti...Antimony; Gallium Arsenide; Nitrogen2002
119 Tiwari, AshutoshSynthesis and atomic-level characterization of Ni nanoparticles in Al2O3 matrixSingle domain magnetic nickel nanocrystals were embedded in alumina matrix using a pulsed-laser deposition technique. Structural characterization carried out at the atomic level using scanning transmission electron microscopy with atomic number contrast (STEM-Z) in conjunction with electron energy ...Nanophase magnetic materials; Alumina2002
120 Smith, Grant D.Viscoelastic properties of polybutadiene in the glassy regime from molecular dynamic simulationsA thorough understanding of the dynamic?mechanical properties of polymer melts and glasses is key to many, if not most, applications of polymers as well as to the processing of polymers.Polymer melts; Polymer glasses; Molecular dynamic simulations2002
121 Tiwari, AshutoshEpitaxial growth of ZnO films on Si(111)In this paper, we report the growth of ZnO films on silicon substrates using a pulsed laser deposition technique. These films were deposited on Si(111) directly as well as by using thin buffer layers of AlN and GaN. All the films were found to have c-axis-preferred orientation aligned with normal to...Buffer layers; Aluminum nitride; Silicon substrate; Biaxial strain2002
122 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
123 Tiwari, AshutoshPulsed laser deposition and characterization of Zn1-xMnxO filmsHere we present our results of structural, optical, and magnetic measurements of Zn1-xMnxO thin films. These films were grown epitaxially on (0001) sapphire substrates by using pulsed laser deposition technique. The maximum Mn content (x=0.36) is found to be much higher than allowed by thermal equl...2002
124 Stringfellow, Gerald B.Effect of surfactant Sb on carrier lifetime in GaInP epilayersSamples of Ga0.52In0.48P grown on (001) GaAs with small amounts of surfactant Sb were investigated using time-resolved photoluminescence. All samples show a luminescence that may be fit to a two-stage exponential decay with a fast and a slow lifetime. For growth without Sb (Sb/III(v)(0), the sample ...Semiconductor ternary alloys; Epitaxial layer; Microstructures2002-01-01
125 Liu, FengSelf-organized nanoscale pattern formation on vicinal Si(111) surfaces via a two-stage faceting transitionWe demonstrate a self-organized pattern formation on vicinal Si(111) surfaces that are miscut toward the [211] direction. All the patterns, consisting of a periodic array of alternating (7 X 7) reconstructed terraces and step-bunched facets, have the same periodicity and facet structure, independent...Vicinal Si(111); Nanoscale pattern formation; Two-stage; Faceting transition2002-02
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