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Filters: Department: "Materials Science & Engineering" School Or College: "College of Engineering" Collection: "ir_uspace" Format: "application/pdf"
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CreatorTitleDescriptionSubjectDate
151 Stringfellow, Gerald B.;Inglefield, Colin E.;Taylor, P. CraigCharacterization of unicompositional GaInP2 ordering heterostructures grown by variation of V/III ratioPhotoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies are employed to investigate single heterostructures based on two GaInP2 layers that have the same composition but different degrees of order on the cation sublattice. Four sample configurations are studied: two complemen...Heterostructures; Growth parameters; Growth temperature1997
152 Stringfellow, Gerald B.Mechanism for liquid phase epitaxial growth of nonequilibrium compositions producing a coherent interfaceA model is presented for growth by so-called composition pulling, wherein an epitaxial deposit grows coherently but with a composition different from that which would be in bulk equilibrium with the liquid phase from which growth occurs. The breakdown of coherent growth occurs when a dislocation nuc...Lattice-matching overgrowths; Composition pulling; Dislocation interface1977
153 Stringfellow, Gerald B.Surfactant controlled growth of GaInP by organometallic vapor phase epitaxyThe 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 agents2000
154 Stringfellow, Gerald B.Sb enhancement of lateral superlattice formation in GaInPEpitaxial 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; Photoluminescence2001
155 Scarpulla, MichaelMagnetic cluster phases of Mn-interstitial-free (Ga,Mn)AsWe report an investigation of magnetic cluster phases of (Ga,Mn)As of varying dosages formed by Mn ion implantation followed by pulsed-laser melting (II-PLM). A systematic study of zero-field-cooled and field-cooled magnetization along several high-symmetry crystallographic directions reveals the ...Magnetic cluster phases; Gallium Arsenide; Ferromagnetic semiconductors; Interstitials2007
156 Tiwari, AshutoshStructural, electrical, and optical characterizations of epitaxial Zn(1-x)Ga(x)O films grown on sapphire (0001) substrateIn this paper we report the structural, electrical, and optical properties of epitaxial Zn1−xGaxO films (x=0-0.05) grown on single crystal sapphire (0001) substrate by pulsed laser deposition technique. Structural and elemental analysis was performed using high-resolution x-ray diffraction (θ-2...Transparent conductive oxides; Gallium2007
157 Liu, FengMetal-to-semiconductor transition in squashed armchair carbon nanotubesWe investigate electronic transport properties of the squashed armchair carbon nanotubes, using tight-binding molecular dynamics and the Green's function method. We demonstrate a metal-to-semiconductor transition while squashing the nanotubes and a general mechanism for such a transition. It is the ...Squashed armchair; Carbon nanotubes; Metal-to-semiconductor transition; Electronic transport; Tight-binding molecular dynamics; Squashed nanotubes2003-04
158 Stringfellow, Gerald B.Atomic force microscopy study of ordered GaInPExamines the nature of the steps on the surface of gallium indium phosphide lattice layers matched to gallium arsenide substrates using atomic force microscopy. Temperatures of organometallic vapor phase epitaxy used; Relation of height of steps with misorientation angle; Link of supersteps with the...Surface chemistry; Lattice theory1995
159 Liu, FengIntrinsic current-voltage properties of nanowires with four-probe scanning tunneling microscopy: a conductance transition of ZnO nanowireWe report intrinsic current-voltage properties of ZnO nanowire measured by a four-tip scanning tunneling microscopy (F-STM). It is found that after bending the nanowire with the F-STM the conductance is reduced by about five orders of magnitude. The cathodoluminescent spectra indicate that the ZnO n...ZnO nanowire; Four-probe; Four-tip; F-STM; Conductance transition2006
160 Liu, FengEffect of size and dimensionality on the magnetic moment of transition metalsThe effect of size and dimensionality on the magnetic moments of Fe, Co, and Ni have been studied theoretically by confining the atoms t o various structural forms such as chains,surfaces, and thin films. The size of these systems is controlled by limiting t h e number of atoms. A new first-princip...Magnetic moment; Dimensionality; Size effects; Fe; Co; Ni1990
161 Tiwari, AshutoshNanostructured DLC-Ag composites for biomedical applicationsWe have synthesized novel diamondlike carbon coatings with silver nanoparticles embedded into the DLC film. The size of silver nanoparticles that are confined into layered structures has been varied from 5 nm to 50 nm using an ingenious pulsed laser deposition technique. The size of nanoparticles wa...Diamondlike carbon coatings; Nanocrystals2003
162 Liu, FengMagnetism and local order: ab initio tight-binding theoryThe effects of the local environment on the electronic structure and magnetic moments of Fe, Co, and Ni have been studied by confining these atoms to assume various structural forms such as chains, surfaces, layers, and crystals. The coordination number of the atoms can thus be changed over a wide r...Local order; Ab-initio tight-binding theory; Magnetic moment; Electronic structure; Fe; Co; Ni1989-04
163 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
164 Liu, FengFirst-principles study of strain stabilization of Ge(105) facet on Si(001)Using the first-principles total energy method, we calculate surface energies, surface stresses, and their strain dependence of the Ge-covered Si (001) and (105) surfaces. The surface energy of the Si(105) surface is shown to be higher than that of Si(001), but it can be reduced by the Ge deposition...First-principles calculation; Strain stabilization; Ge(105); Si(001); Strained thin films; Epitaxial growth2005-09
165 Stringfellow, Gerald B.Solid phase immiscibility in GaInNThe large difference in interatomic spacing between GaN and InN is found to give rise to a solid phase miscibility gap. The temperature dependence of the binodal and spinodal lines in the Ga1xInxN system was calculated using a modified valence-force-field model where the lattice is allowed to relax ...Interatomic spacing; Valence-force field; epitaxial growth1996
166 Liu, FengEquilibrium shape of two-dimensional islands under stressWe 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; Homoepitaxy2000-08
167 Scarpulla, MichaelEffects of pressure on the band structure of highly mismatched Zn1-yMnyOxTe1-x alloysWe report photomodulation spectroscopy measurements of the pressure dependence of the optical transition in Zn12yMnyOxTe1-x alloys that is associated with the lowest Ѓ conduction band (termed E2 subband). The pressure-induced energy shift of the E2 transition is nonlinear and much weaker as compare...Highly mismatched alloys; Zinc telluride; Anticrossing2004
168 Liu, Feng(BAl12)Cs: a cluster-assembled solidFirst-principles calculations on the geometry and stability of AlnBm clusters have been carried out to examine the effect of size, composition, and electronic-shell filling on their relative stability. It is shown that although Al and B are both trivalent, a BAl12 cluster is more stable than an Al1...First-principles calculations; (BAl12)Cs; Cluster-assembled; AlnBm clusters1997-06
169 Tiwari, AshutoshCopper diffusion characteristics in single crystal and polycrystalline TaNTaN has become a very promising diffusion barrier material for Cu interconnections, due to the high thermal stability requirement and thickness limitation for next generation ULSI devices. TaN has a variety of phases and Cu diffusion characteristics vary with different phases and microstructures. We...Diffusion barriers; Copper diffusion; Tantalum nitride2003
170 Liu, FengStep-induced optical anisotropy of vicinal Si(001)It is demonstrated, using reflectance difference spectroscopy, scanning tunneling microscopy, and low-energy electron diffraction, combined with deliberate straining of the surface, that the presence of atomic steps dramatically changes the optical anisotropy of the Si(001) surface. The step-induce...Step-induced; Optical anisotropy; Vicinal Si(001); Electron diffraction; Atomic steps1999-01
171 Stringfellow, Gerald B.Effects of surfactants Sb and Bi on the incorporation of zinc and carbon in III/V materials grown by organometallic vapor-phase epitaxyThe incorporation of both dopants and background impurities during the organometallic vapor phase epitaxial _x0002_OMVPE_x0003_ growth of GaAs, GaInP, and GaP has been significantly altered by the use of the surfactants Sb and Bi. Sb and Bi are isoelectronic with the group V host elements, and so ...Physical and chemical processes; Surfactants isoelectronic; Electrochemical C-V profilometry2006
172 Tiwari, AshutoshRectifying electrical characteristics of La0.7Sr0.3MnO3/Zno heterostructureWe have fabricated a p - n junction, consisting of p-type manganite (La0.7Sr0.3MnO3) and n-type ZnO layers grown on sapphire substrate. This junction exhibits excellent rectifying behavior over the temperature range 20-300 K. Electrical characteristics of La0.7Sr0.3MnO3 (LSMO) film in this heterostr...Manganites2003
173 Stringfellow, Gerald B.Dislocations in GaAs17-xPxDislocations, their origins, and their effects on photoluminescence efficiency have been studied in GaAs1-xPx single crystals grown by vapor phase epitaxy. Dislocations were observed using etch pit, optical-transmission microscopy, and x-ray topography techniques. Two types of dislocations are grown...Photoluminescence efficiency; Growth mechanism; Optical transmission microscopy1969
174 Liu, FengAnisotropic strain enhanced hydrogen solubility in bcc metals: the independence on the sign of strainWhen an impurity is doped in a solid, it inevitably induces a local stress, tending to expand or contract the lattice. Consequently, strain can be applied to change the solubility of impurity in a solid. Generally, the solubility responds to strain ‘‘monotonically,'' increasing (decreasing) with...2012-01-01
175 Stringfellow, Gerald B.; Inglefield, Colin E.; Taylor, P. CraigQuantum wells due to ordering in GaInPCuPt ordering results in a reduction of the band-gap energy of GaInP. Thus, heterostructures and quantum wells can be produced by simply varying the order parameter, without changing the solid composition. Changes in the order parameter can be induced by changes in growth conditions. The disorder...Band-gap energy; Growth temperature; Quantum wells1998-12-28
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