UScholar Works
 
Filters: Department: "Materials Science & Engineering" Collection: "ir_uspace"
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CreatorTitleDescriptionSubjectDate
1 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
2 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
3 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
4 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
5 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
6 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
7 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
8 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
9 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
10 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
11 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
12 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
13 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
14 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
15 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
16 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
17 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
18 Liu, FengNanostressors and the nanomechanical response of a thin silicon film on an insulatorPseudomorphic three-dimensional Ge nanocrystals (quantum dots) grown on thin silicon-on-insulator substrates can induce significant bending of the silicon template layer that is local on the nanometer scale. We use molecular dynamics simulations and analytical models to confirm the local bending of...Nanostressors; Nanomechanical response; Thin silicon film2002-09
19 Liu, FengSelf-assembly of three-dimensional metal islands: nonstrained versus strained islandsA theoretical model for the Volmer-Weber growth of three-dimensional metal islands is proposed, with a dipolar island edge-edge interaction. The existence of such an island edge effect makes the island shape dependent on island size. Furthermore, it induces a stable island size against coarsening, l...Self-assembly; Three dimensional islands; Metal islands; Nonstrained islands; Strained islands; Volmer-Weber growth2002-11
20 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
21 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
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