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Creator | Title | Description | Subject | Date |
76 |
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Stringfellow, Gerald B.; Shurtleff, James Kevin | Bi surfactant effects on ordering in GaInP grown by organometallic vapor-phase epitaxy | The effect of the isoelectronic surfactant Bi on surface structure and ordering has been studied for GaInP semiconductor alloys grown by organometallic vapor-phase epitaxy. A small amount of Bi trimethylbismuth added during growth is found to result in disordering for layers grown using conditions t... | Surfactant; Semiconductors; Trimethylbismuth | 2000 |
77 |
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Stringfellow, Gerald B.; Shurtleff, James Kevin | Adsorption and desorption of the surfactant Sb on GaInP grown by organometallic vapor phase epitaxy | It 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 alloys | 2000 |
78 |
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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 study | Equilibrium 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 explosives | 2000 |
79 |
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Stringfellow, Gerald B. | Bi surfactant control of ordering and surface structure in GaInP grown by organometallic vapor phase epitaxy | Studies the effect of the surfactant bismuth on the ordering and surface structure in GaInP layers grown by organometallic vapor phase epitaxy. Disordering caused by the addition of bismuth during growth; Changes in surface structure occurring with the disordering. | Thin films, Multilayered; Bismuth | 2000 |
80 |
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Bedrov, Dmitro; Smith, Grant D. | Thermal conductivity of molecular fluids from molecular dynamics simulations: application of a new imposed-flux method | We 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 method | 2000 |
81 |
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Stringfellow, Gerald B. | Surfactant controlled growth of GaInP by organometallic vapor phase epitaxy | The effect of the surfactant Sb has been studied for GaInP semiconductor alloys grown by organometallic vapor phase epitaxy. Dramatic changes in the optical and electrical properties of GaInP with CuPt ordering have been observed. A small concentration of triethylantimony TESb in the vapor is fou... | Semiconductors; Surface active agents | 2000 |
82 |
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Smith, Grant D. | Prediction of the linear viscoelastic shear modulus of an entangled polybutadiene melt from simulation and theory | While 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 polymers | 2000 |
83 |
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Smith, Grant D. | Quantum chemistry based force field for simulations of poly(vinylidene fluoride) | A classical potential function for simulations of poly(vinylidene fluoride) (PVDF) based upon quantum chemistry calculations on PVDF oligomers has been developed. Quantum chemistry analysis of the geometries and conformational energies of 1,1,1,3,3-pentafluorobutane (PFB), 1,1,1,3,3,5,5,5-octofluoro... | Poly(vinylidene fluoride) simulations; PVDF | 2000 |
84 |
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Tiwari, Ashutosh | Experiments along coexistence near tricriticality in 3He-4He mixtures | The tricritical point in the phase diagram of 3He-4He mixtures offers unique opportunities to test our understanding of critical phenomena. Because D = 3 is the marginal spatial dimension for tricriticality, the associated critical exponents are exact integer fractions. In addition, one expects to f... | Tricriticality; Tricritical point; 3He-4He mixtures | 2000 |
85 |
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Liu, Feng | First-principles study of impurity segregation in edge dislocations in Si | Using ab initio calculations, the segregation of As, Ga, and Ge atoms in the core regions of perfect edge dislocations in Si is examined. When all nearest neighbors of an impurity are Si atoms, As favors the core site at maximum compression and has a segregation energy of 0.25 eV/atom. Ga and Ge im... | First-principles; Impurity segregation; Edge dislocations | 2000-01 |
86 |
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Scarpulla, Michael | New methodologies for measuring film thickness, coverage, and topography | We 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 reflectivity | 2000-01 |
87 |
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Stringfellow, Gerald B.; Shurtleff, James Kevin | Use of surfactant Sb to induce triple period ordering in GaInP | A 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; Surfactant | 2000-03-13 |
88 |
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Liu, Feng | Equilibrium shape of two-dimensional islands under stress | We show that the equilibrium shape anisotropy of two-dimensional islands in heteroepitaxial growth depends on island size, a consequence of the presence of strain. Even in homoepitaxy, in which the island shape has conventionally been equated with the ratio of step energies, a substrate surface str... | Two-dimensional islands; Equilibrium shape; Heteroepitaxial growth; Homoepitaxy | 2000-08 |
89 |
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Liu, Feng | Thermal roughening of a thin film: a new type of roughening transition | The 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 growth | 2000-09 |
90 |
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Liu, Feng | Magnetization on rough ferromagnetic surfaces | Using Ising-model Monte Carlo simulations, we show a strong dependence of surface magnetization on surface roughness. On ferromagnetic surfaces with spin-exchange coupling larger than that of the bulk, the surface magnetic ordering temperature decreases toward the bulk Curie temperature with incre... | Ferromagnetic surfaces; Surface magnetization | 2000-11 |
91 |
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Liu, Feng | Unique 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; Energetics | 2000-12 |
92 |
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Liu, Feng | Creation of "quantum platelets" via strain-controlled self-organization at steps | We demonstrate, by both theory and experiment, the strain-induced self-organized formation of "quantum platelets," monolayer-thick islands of finite dimensions. They form at the early stage of heteroepitaxial growth on a substrate with regularly spaced steps, and align along the steps. In the direc... | Quantum platelets; Strain-controlled self-organization; Monolayer-thick islands; Heteroepitaxial growth | 2000-12 |
93 |
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Stringfellow, Gerald B. | Spectroscopic study of surfactant enhanced organometallic vapor phase epitaxy growth of GaInP | Samplen 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; Spectroscopy | 2001 |
94 |
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Stringfellow, Gerald B. | Kinetics of Te doping in disordering GaInP grown by organometallic vapor phase epitaxy | Te-doped GaInP epitaxial layers were grown by organometallic vapor phase epitaxy in an effort to clarify the Te disordering mechanism. CuPt ordered GaInP is produced under normal growth conditions. The addition of Te has been reported to induce disorder. One suggested mechanism for disordering GaInP... | Crystal growth; Epitaxy; Dynamics | 2001 |
95 |
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Liu, Feng | Pattern formation via a two-step faceting transition on vicinal Si(111) surfaces | We 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); Miscut | 2001 |
96 |
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Smith, Grant D. | On the non-Gaussianity of chain motion in unentangled polymer melts | We 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 echo | 2001 |
97 |
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Stringfellow, Gerald B. | Sb enhancement of lateral superlattice formation in GaInP | Epitaxial layers of GaInP were grown by organometallic vapor phase epitaxy with small amounts of TESb added to control the surface bonding. Above a concentration of Sb/III(v)=0.016, 12 K photoluminescence measurements show that the band gap is reduced, as compared to completely disordered GaInP, by ... | Tin; Epitaxy; Photoluminescence | 2001 |
98 |
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Bedrov, Dmitro; Smith, Grant D. | Integral equation theory for polymer solutions: explicit inclusion of the solvent molecules | Self-consistent Polymer Reference Interaction Site Model (PRISM) calculations and molecular dynamics (MD) simulations were performed on athermal solutions of linear polymers. Unlike most previous treatments of polymer solutions, we explicitly included the solvent molecules. The polymers were mode... | Solvent molecules; Polymer Reference Interaction Site Model; PRISM; Spinodal curve; Intramolecular dimensions; Intermolecular packing; Phase behavior | 2001 |
99 |
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Pugmire, Ronald J. | Soot formation during coal pyrolysis | Soot can be found in almost all combustion and pyrolysis systems. In a coal system, the impact of soot on coal combustion can be identified in two ways. First, soot particles suspended in the combustion flame significantly enhance radiative heat transfer near the burner due to their large surface ar... | | 2001 |
100 |
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Smith, Grant D.; Borodin, Oleg; Bedrov, Dmitro | 13C NMR spin-lattice relaxation and conformational dynamics in a 1,4-polybutadiene melt | We have performed molecular dynamics (MD) simulations of a melt of 1,4-polybutadiene (PBD, 1622 Da) over the temperature range 400?273 K. 13C NMR spin?lattice relaxation times (T1) and nuclear Overhauser enhancement (NOE) values have been measured from 357 to 272 K for 12 different resonances. The T... | Polybutadiene melt; 13C NMR; Spin-lattice relaxation; Conformational dynamics; Molecular dynamics simulation | 2001 |