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Creator | Title | Description | Subject | Date |
126 |
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Stringfellow, Gerald B. | Correlation between surface structure and ordering in GaInP | Ga and In atoms in Ga0.52In0.48P layers spontaneously segregate to form alternating In- and Ga-rich {111} monolayers during organometallic vapor phase epitaxial (OMVPE) growth on (001) oriented GaAs substrates, thus forming the CuPt ordered structure. This ordering phenomenon is believed to be drive... | Transformations; Absorbtion spectra; Surface Properties | 1996 |
127 |
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Scarpulla, Michael | Compositional tuning of ferromagnetism in Ga1-xMnxP | We report the magnetic and transport properties of Ga1-xMnxP synthesized via ion implantation followed by pulsed laser melting over a range of x, namely 0.018 to 0.042. Like Ga1-xMnxAs, Ga1-xMnxP displays a monotonic increase of the ferromagnetic Curie temperature with x associated with the hole-me... | Gallium arsenide; Ferromagnetic semiconductors | 2006-12 |
128 |
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Liu, Feng | Influence of quantum size effects on Pb island growth and diffusion barrier oscillations | Quantum size effects are successfully exploited in manipulating the growth of (111) oriented Pb islands on Si(111) substrate with a scanning tunneling microscope. The growth dynamics and morphology displayed can be well controlled through the quantum size effects defined by the island thicknesses ... | Quantum size effects; QSE; Pb island; Diffusion barrier oscillations | 2006-08 |
129 |
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Stringfellow, Gerald B. | Step structure and ordering in Zn-doped GaInP | Presents the results of a study of Zinc dopant effects on both step structure and ordering in GaInP in an effort to further clarify the disordering mechanism. Comparison of the results obtained for Zinc with those reported for tellurium; Experiment; Results; Discussion; Conclusion. | Gallium Compounds; Zinc; Ordering | 1999 |
130 |
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Tiwari, Ashutosh | Metallic conductivity and metal-semiconductor transition in Ga-doped ZnO | This letter reports the metallic conductivity in Ga:ZnO system at room temperature and a metal-semiconductor transition (MST) behavior at low temperatures. Zn0.95Ga0.05O films, deposited by pulsed laser deposition in the pressure range of ~10−2 Torr of oxygen, were found to be crystalline and exhi... | Transparent conducting oxides; ZnO; Gallium; Metallic conductivity | 2006 |
131 |
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Liu, Feng | Pattern formation on silicon-on-insulator | The strain driven self-assembly of faceted Ge nanocrystals during epitaxy on Si(001) to form quantum dots (QDs) is by now well known. We have also recently provided an understanding of the thermodynamic driving force for directed assembly of QDs on bulk Si (extendable to other QD systems) based on ... | Pattern formation; Silicon-on-insulator; Strain driven; Faceted Ge nanocrystals; Si(001); Directed assembly | 2005 |
132 |
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Tiwari, Ashutosh | Ferromagnetism in Co doped CeO2: observation of giant magnetic moment with a high Curie temperature | We report room temperature ferromagnetism in single crystal Ce1−xCoxO2−δ (x≤0.05) films deposited on a LaAlO3(001) substrate. Films were grown by a pulsed laser deposition technique and were thoroughly characterized using x-ray diffraction, high-resolution transmission electron microscopy cou... | CeO2; Cobalt | 2006 |
133 |
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Scarpulla, Michael | Suppression of hole-mediated ferromagnetism in Ga1-xMnxP by hydrogen | We 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; Hydrogenation | 2008 |
134 |
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Tiwari, Ashutosh | Epitaxial growth and properties of Zn1-xVxO diluted magnetic semiconductor thin films | Here we report systematic studies on the epitaxial growth and properties of Zn1−xVxO[x=0.001-0.2] thin films deposited onto sapphire c-plane single crystals. The thin films were deposited using pulsed laser deposition technique and were found to be epitaxial in nature. X-ray diffraction and high ... | ZnO; Vanadium | 2005 |
135 |
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Stringfellow, Gerald B. | Kinetically controlled order/disorder structure in GaInP | A Ga0.52In0.58p order/disorder heterostructure having a band-gap energy difference exceeding 160 meV has been grown by organometallic vapor phase epitaxy. The two layers were grown on a nominally (OOl)-oriented GaAs substrate misoriented by 3° toward the [110] direction in the lattice. The disorder... | Indium phosphides; Gallium Phosphides; Heterojunctions | 1994 |
136 |
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Chaudhuri, Reaz A. | Interlaminar shear stresses around an internal part-through hole in a stretched laminated composite plate | The equilibrium/compatibility method, which is a semi-analytical post-processing method, is employed for computation of hitherto unavailable through-thickness variation of interlaminar (transverse) shear stresses in the vicinity of the bi-layer interface circumferential re-entrant corner line of an... | | 2010-03 |
137 |
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Liu, Feng | Local strain-mediated chemical potential control of quantum dot self-organization in heteroepitaxy | From observations of self-assembly of Ge quantum dots directed by substrate morphology, we propose the concept of control of ordering in heteroepitaxy by a local strain-mediated surface chemical potential. Using quite simple lithography, we demonstrate directed quantum dot ordering. The strain part ... | Self-organization; Heteroepitaxy; Chemical potential control; Ge quantum dots | 2004-01 |
138 |
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Liu, Feng | Magnetism in nanopatterned graphite film | Using 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; NPGF | 2008 |
139 |
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Liu, Feng | Simple theory of the electronic structure: clusters to crystals | A simple scheme based upon a cross between the molecular clusters and the tight-binding theory has been developed to calculate the electronic structure of a large class of systems ranging from molecules to solids. The method is applied to study the variations in the magnetic moments of Fe and Ni for... | Clusters; Tight-binding theory; Magnetic moment | 1988-09 |
140 |
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Liu, Feng | Magnetism in small vanadium clusters | Using the self-consistent-field molecular-orbital theory and the density-functional approximation, we show that vanadium could become magnetic if its size and dimension were constrained. This is illustrated for vanadium forming clusters with body-centered-cubic (bcc) geometry as well as for linear c... | Vanadium clusters; Molecular-orbital theory; Density-functional approximation; Stoner criterion | 1991-04 |
141 |
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Tiwari, Ashutosh | Growth and characterization of TaN/TiN superlattice structures | Epitaxial B1 NaCl-structured TaN(3 nm)/TiN(2 nm) superlattice structures were grown on Si(100) substrates with a TiN buffer layer, using pulsed-laser deposition. A special target assembly was used to manipulate the thickness of each layer. X-ray diffraction, transmission electron microscopy, and ... | Diffusion barriers; Copper diffusion; Tantalum nitride | 2003 |
142 |
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Liu, Feng | Pressure-induced hard-to-soft transition of a single carbon nanotube | We demonstrate a hydrostatic pressure-induced hard-to-soft transition of an isolated single wall carbon nanotube, using classical and ab initio constant-pressure molecular-dynamics simulations and continuum elastic theory analysis. At low pressure, the carbon tube is hard. Above a critical pressur... | Carbon nanotubes; Hard-to-soft transition | 2004-10 |
143 |
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Stringfellow, Gerald B. | Heterostructures in GaInP grown using a change in V/III ratio | A natural monolayer 111% superlattice -- the CuPt ordered structure -- is formed spontaneously during organometallic vapor phase epitaxial OMVPE growth of Ga0.52In0.48P. The extent of this ordering process is found to be a strong function of the input partial pressure of the phosphorus precursor dur... | Superlattices; Alloys; Atomic ordering; Heterostructures | 1997-02-24 |
144 |
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Stringfellow, Gerald B. | Step structure and ordering in Te-doped GaInP | The step structure and CuPt ordering in GaInP layers grown by organometallic vapor phase epitaxy on singular GaAs substrates have been investigated as a function of Te (DETe) doping using atomic force microscopy, and electrical and optical properties measurements. The degree of order decreases for T... | Surfaces; Te doping; Bandgap energy | 1998 |
145 |
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Tiwari, Ashutosh | Characterization of Li7La3Zr2O 12 thin films prepared by pulsed laser deposition | A pulsed laser deposition system was employed to fabricate thin films of Li7La3Zr2O12 solid electrolyte. The deposition process was carried out at room-temperature, resulting in amorphous films. These as-deposited films had a large optical band gap of 5.13 eV, and exhibited a lithium-ion conductivit... | | 2012-01-01 |
146 |
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Scarpulla, Michael | Detection of ZnS phases in CZTS thin-films by EXAFS | Copper zinc tin sulfide (CZTS) is a promising Earthabundant thin-film solar cell material; it has an appropriate band gap of ~1.45 eV and a high absorption coefficient. The most efficient CZTS cells tend to be slightly Zn-rich and Cu-poor. However, growing Zn-rich CZTS films can sometimes result in ... | | 2011-01-01 |
147 |
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Liu, Feng | Computational R&D for industrial applications | Recent advances in high-speed supercomputer and computational algorithms have brought us into a new era of computational materials science. These advances make it possible to investigate many existing materials systems that were previously considered intractable and also predict and design novel mat... | Computational materials science | 2005 |
148 |
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Liu, Feng | Suppression of spin polarization in graphene nanoribbon by edge defects and impurities | We 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; GNR | 2008-04 |
149 |
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Scarpulla, Michael | Investigating sputtered Cu2Si1-xSnxS3 (CSTS) for earth abundant thin film photovoltaics | This study investigates the synthesis of chalcopyrite Cu2Si1-xSnxS3 (CSTS) thin films for photovoltaic solar cell absorber layers. Preliminary results indicate that layered sputtering of Cu, Sn, and Si followed by annealing in a sulfur atmosphere at 500⁰C does not provide adequate mixing or sulfu... | | 2010 |
150 |
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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 |