UScholar Works
 
Filters: Department: "Materials Science & Engineering" Collection: "ir_uspace" Type: "Text"
201 - 225 of 288
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CreatorTitleDescriptionSubjectDate
201 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
202 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
203 Tiwari, AshutoshCuBO2: a p-type transparent oxideThe authors report the synthesis of CuBO2, a p-type transparent oxide belonging to Cu-delafossite family. High quality thin films of CuBO2 were deposited on c-plane sapphire substrates by pulsed laser deposition technique. Detailed structural, optical, and electrical characterizations on these films...Transparent conducting oxides; Delafossite series; CuBO22007
204 Ostafin, AgnesCombined deletion of mouse dematin-headpiece and ß-adducin exerts a novel effect on the spectrin-actin junctions leading to erythrocyte fragility and hemolytic AnemiaDematin and adducin are actin-binding proteins of the erythrocyte "junctional complex." Individually, they exert modest effects on erythrocyte shape and membrane stability, and their homologues are expressed widely in non-erythroid cells. Here we report generation and characterization of double knoc...2007
205 Borodin, Oleg; Smith, Grant D.; Bedrov, DmitroPolarizable and nonpolarizable force fields for alkyl nitratesQuantum-chemistry-based many-body polarizable and two-body nonpolarizable atomic force fields were developed for alkyl nitrate liquids and pentaerythritol tetranitrate (PETN) crystal. Bonding, bending, and torsional parameters, partial charges, and atomic polarizabilities for the polarizable force f...Alkyl nitrate; Pentaerythritol tetranitrate; PETN; Polarizable atomic force fields; Nonpolarizable atomic force fields2007
206 Liu, FengMaking a field effect transistor on a single graphene nanoribbon by selective dopingUsing first-principles electronic structure calculations, we show a metal-semiconductor transition of a metallic graphene nanoribbon with zigzag edges induced by substitutional doping of nitrogen or boron atoms at the edges. A field effect transistor consisting of a metal-semiconductor-metal junctio...Graphene nanoribbon; Selective doping2007
207 Liu, FengImpurity mediated absorption continuum in single-walled carbon nanotubesThe authors demonstrate that in single-walled carbon nanotubes, a weak impurity potential can lead to a strong above-gap absorption continuum. The total absorption is enhanced due to the intraband and indirect transitions, as well as plasmon excitations, which are forbidden in perfect nanotubes. Suc...Carbon nanotubes; SWNT; Defects; Impurities; Above-gap; Absorption continuum2007
208 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
209 Scarpulla, MichaelMagnetocrystalline anisotropy and magnetization reversal in Ga1-xMnxP synthesized by ion implantation and pulsed-laser meltingWe report the observation of ferromagnetic resonance (FMR) and the determination of the magnetocrystalline anisotropy in (100)-oriented single-crystalline thin film samples of Ga1−xMnxP with x=0.042. The contributions to the magnetic anisotropy were determined by measuring the angular and the te...Magnetocrystalline anisotropy; GaMnAs; Gallium arsenide2007-06
210 Scarpulla, MichaelDetermination of the infrared complex magnetoconductivity tensor in itinerant ferromagnets from Faraday and Kerr measurementsWe present measurement and analysis techniques that allow the complete complex magnetoconductivity tensor to be determined from midinfrared (11-1.6 μm; 100-800 meV) measurements of the complex Faraday (θF) and Kerr (θK) angles. Since this approach involves measurement of the geometry (orientati...Magnetoconductivity tensor; Ferromagnets2007-06
211 Scarpulla, MichaelElectrical transport and ferromagnetism in Ga1−xMnxAs synthesized by ion implantation and pulsed-laser meltingWe present a detailed investigation of the magnetic and magnetotransport properties of thin films of ferromagnetic Ga1−xMnxAs synthesized using ion implantation and pulsed-laser melting (II-PLM). The field and temperature-dependent magnetization, magnetic anisotropy, temperature-dependent resist...GaMnAs; Gallium arsenide2008
212 Liu, FengRole of vacancy on trapping interstitial O in heavily As-doped SiWe have investigated the interstitial oxygen (Oi) diffusion in heavily arsenic (As)-doped Si using first-principles calculations. We show that it is not the As per se but the Si vacancy (V) that trap Oi to reduce its diffusion. Arsenic actually plays the role of an arbitrator to activate thermal ge...Vacancy; Interstitial oxygen; As-doped Si; Arsenic doped silicon; Oxygen trapping; Oxygen diffusion2008
213 Scarpulla, MichaelGa1-xMnxP synthesized by ion implantation and pulsed-laser meltingThe synthesis of single-crystalline epitaxial thin films of the carrier-mediated ferromagnetic phase of Ga1-xMnxP and Ga1-xMnxP-based quaternary alloys using ion implantation and pulsed-laser melting (II-PLM) has allowed for the exploration of the effect of anion substitution on ferromagnetism in Ga...2008
214 Scarpulla, MichaelNear-infrared absorption and semimetal-semiconductor transition in 2 nm ErAs nanoparticles embedded in GaAs and AlAsWe report strong near-infrared absorption peaks in epitaxial films of GaAs and AlAs containing approximately 0.5-5% of the semimetal ErAs. The energy of the resonant absorption peak can be changed from 0.62 to 1.0 eV (2.2-1.4 μm) by variation of the ErAs volume fraction and the substrate temperatu...Near-infrared absorption; Semimetal-semiconductor transition; GaAs; AlAs; ErAs; Gallium arsenide; Aluminum arsenide2008
215 Scarpulla, MichaelSuppression of hole-mediated ferromagnetism in Ga1-xMnxP by hydrogenWe report the passivation of the Mn acceptors in Ga1−xMnxP upon exposure to a hydrogen plasma. The as-grown films are nonmetallic and ferromagnetic with a Curie temperature of TC=55 K. After hydrogenation the sample resistivity increases by approximately three orders of magnitude at room tempera...Ferromagnetic semiconductors; Hydrogenation2008
216 Liu, FengMagnetism in nanopatterned graphite filmUsing first-principles calculations, we show that nanopatterned graphite films (NPGFs) can exhibit magnetism in analogy to graphene-based nanostructures (GBNs). In particular, graphite films with patterned nanoscale triangular holes and channels with zigzag edges all have ferromagnetic ground state...Nanopatterned graphite; Graphite films; NPGF2008
217 Liu, FengModified Timoshenko formula for bending of ultrathin strained bilayer filmsMechanical bending of nanoscale thin films can be quite different from that of macroscopic thick films. However, current understanding of mechanical bending of nanoscale thin strained bilayer films is often limited within the Timoshenko model [Timoshenko, J. Opt. Soc. Am. 11, 233 (1925)], which was ...Timoshenko formula; Bending theory; Ultrathin films; Strained nanoscale thin films; Nanofilms2008
218 Liu, FengKinetics of mesa overlayer growth: climbing of adatoms onto the mesa topWe have calculated the energy barriers for an adatom climbing up onto a Pb mesa top either over a facet-facet edge or through a facet-step joint, using a modified embedded atom method. We found that the second process is not only thermodynamically more favorable than the first one but also much fast...Mesa overlayer growth; Adatoms; Epitaxial growth2008
219 Scarpulla, MichaelNonmagnetic compensation in ferromagnetic Ga1-xMnxAs and Ga1-xMnxP synthesized by ion implantation and pulsed-laser meltingThe electronic and magnetic effects of intentional compensation with nonmagnetic donors are investigated in the ferromagnetic semiconductors Ga1−xMnxAs and Ga1−xMnxP synthesized using ion implantation and pulsed-laser melting. It is demonstrated that compensation with nonmagnetic donors and MnI ...Ferromagnetic semiconductors2008
220 Liu, FengEnhanced growth instability of a strained film on wavy substrateWe demonstrate that the growth of a strained film is inherently less stable on a wavy substrate than on a flat substrate. For small surface undulation, the lowest strain energy state is for the film surface to adopt the same wavelength as the substrate surface in an antiphase configuration at the ea...Growth instability; Strained film; Wavy substrate; Strain induced self-assembly2008
221 Tiwari, AshutoshBand-gap engineering of Zn1-xGaxO nanopowders: synthesis, structural and optical characterizationsWe report the preparation and detailed structural and optical characterizations of single phase gallium doped ZnO nanopowders. A low temperature solution-based technique was developed to synthesize high-purity Zn1−xGaxO (x:0-0.05) nanopowders. Structural and optical characterization experiments we...Zinc gallium oxide; ZnGaO; Nanopowders; Band-gap engineering2008
222 Tiwari, AshutoshFerromagnetism in Cu-doped ZnO films: role of charge carriersWe report the observation of room temperature ferromagnetism in Cu-doped (5%) ZnO films grown on c-plane sapphire substrates. Films were prepared by pulsed laser deposition technique and were thoroughly characterized using several state-of-the-art characterization techniques. Hall measurements sho...Charge carriers2008
223 Liu, FengSuppression of spin polarization in graphene nanoribbon by edge defects and impuritiesWe investigate the effect of edge defects (vacancies) and impurities (substitutional dopants) on the robustness of spin polarization in graphene nanoribbons (GNRs) with zigzag edges by using density-functional-theory calculations. The stability of the spin state and its magnetic moments is found to ...Edge defects; Vacancy; Spin-polarization; Graphene nanoribbon; GNR2008-04
224 Bedrov, Dmitro; Smith, Grant D.Thermodynamic, transport and viscoelastic properties of PBX-9501 binder: a molecular dynamics simulation studyAtomistic molecular dynamics simulations were performed on a low molecular weight nitroplasticized Estane® mixture representative of the binder used in PBX-9501. Pressurevolume-temperature (PVT) behavior over a wide range of pressure and temperatures above the order-disorder temperature (ODT) of Es...PBX-9501 binder; Estane; Viscosity; Shear stress relaxation modulus2008-04-04
225 Liu, FengTheory of directed nucleation of strained islands on patterned substratesWe develop a theoretical model to elucidate the nucleation of strained islands on patterned substrates. We show that island nucleation is directed to the preferred sites by a much lower energy barrier and smaller critical size. Strain relaxation directs island nucleation to the bottom of a pit rat...Directed nucleation; Strained islands; Patterned substrates2008-11
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