Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 24 for “"impurity scattering"”.
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Transport properties along the channel of a Hemt
… field along the channel. In this study, the scattering rates for polar optical phonons (POP), acoustic phonons (AP) through deformation potential and impurity scattering are obtained theoretically based on the Fermi's golden rule as a function of position along the channel for an …
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Transport and relaxation properties in anisotropic superconductors
… very low temperatures if resonant non-magnetic impurity scattering effect is included self-consistently in the calculations. The magnetic field effect on T1 is also studied, and we found that for high enough fields a new process, the pair creation process, will dominate the relaxation which …
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Temperature Dependence of the Penetration Depth in the Unconventional Superconductor Strontium Ruthenate
… in determining the temperature dependence than impurity scattering, and are sufficient to explain the deviation from the linear behavior expected for local superconductors with line nodes. These results are inconsistent with the candidate p-wave states predicted by leading theories.
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Temperature dependence of the penetration depth in the unconventional superconductor Sr2RuO4
… in determining the temperature dependence than impurity scattering, and are sufficient to explain the deviation from the linear behavior expected for local superconductors with line nodes. These results are inconsistent with the candidate p-wave states predicted by leading theories.
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Exciton transport and thermodynamics in gallium arsenide quantum wells
… and I describe the transport using an ionized-impurity scattering model. I also measure the carrier temperatures from the high energy slopes of the time-resolved photoluminescence spectra, and describe the roles of the carrier temperatures and carrier expansion on the time dynamics of the …
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Study of localization and correlation effects in disordered electronic systems
… magnetic ordering. The effects of spin-dependent impurity scattering is studied in chapter 5 by introducing random spin-orbit coupling. There is indication of competing interactions in a lattice system with a half-filled band in the ultra-localized limit suggesting the possibility of having …
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Monte Carlo Calculations of Parallel and Perpendicular Electron Transport in Gallium-Arsenide Heterolayers
… study in terms of electronic states and scattering mechanisms for these important artificial semiconductor structures. Polar optical, acoustic phonon scattering (coupled by the deformation potential or piezoelectrically) and ionized impurity scattering are taken into consideration. The …
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Analysis of coulomb interaction using modified particle-particle-particle-mesh method in Monte Carlo simulation
… (EMC) simulator, MOCA3D, to treat the Coulomb scattering, i.e. carrier-carrier and carrier-impurity scattering. We show that most of the problems in the particle{mesh (PM) based scattering rate approach are solved by the P3M method. The properties of the Coulomb scattering are analyzed by …
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Growth of low disorder GaAs/AlGaAs heterostructures by molecular beam epitaxy for the study of correlated electron phases in two dimensions
… indicating a cross-over between dominant scattering mechanisms at low density and high density. At low density the mobility was found to be limited by remote ionized impurity scattering, while at high density the dominant scattering mechanism was found to be background impurity …
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Effects of isotope doping on the phonon modes in graphene
… values of the phonon lifetimes due to isotope impurity scattering for all values of isotopic fractions, isotopic masses and for all wave-vectors using second order perturbation theory. We found that for natural concentrations of 13C, the contribution of isotopic scattering of optical modes is …
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Theory of graphene transport properties
… relative contributions of Coulomb and resonant impurity scattering to graphene resistivity. We establish that the nonuniversal high-density behavior of &sigma(n) in different graphene samples on various substrates arises from the competition among different scattering mechanisms, and it is …
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Transport properties of anisotropic superconductors
… qualitatively as one would expect if electron-impurity interactions were the dominant source of scattering. The experimental data on ultrasonic attenuation and thermal conduction in the superconducting phase of UPt3 do not behave as one would expect if the electron-impurity phase shift were …
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Electronic Transport in Highly Mismatched InAs Films on GaAs
… to lower electron mobilities due to more Coulomb scatterings. For all the n-type InAs films, except the two active layers (surface and the bulk), the nucleation layer contributes to the film conductivity as well with an electron density of ~ 5 x 10¹⁷ cm⁻³ and a mobility of ~ 2000 cm²}/Vs. In a …
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Investigation of doped ZnO by Molecular Beam Epitaxy for n- and p-type Conductivity
… crystalline structures, studies revealed ionized impurity scattering being the dominant mechanism limiting the mobility in the temperature range of 15-330 K, while polar optical phonon scattering being the mechanism responsible for the temperature-dependence for T>150 K. The majority Sb ions were …
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Effects of anisotropy of the superconducting energy gap
… Aa(ro} is extensively examined as a function of impurity concentration: it is found, for example, that the magnitude of the anisotropic part Aa(ro) of the gap parameter tends to zero in the limit of large impurity concentration. A model calculation, assuming a rectangular shape for the anisotropy …
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Nanostructured materials for photovoltaics and microwave electronics: methods and applications
… tested as photoanodes in DSSCs. Superior light scattering properties, stemming from their sub-micrometric mesoporous structure, were proved for TiO2 beads synthesized by using the exadecylamine method. An energy conversion efficiency ŋ = 7.0 % was achieved. The second stage of the research aimed …
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I. Raman scattering and x-ray diffraction study of annealing effects on confined LO and folded LA phonons in GaAs-AlAs superlattices ; II. Picosecond light scattering studies of relaxation and tunneling in GaAs/AlxGa1-xAs mulitple quatum well structures
We have used light scattering techniques to probe the vibrational properties ofGaAs/AlAs superlattices and the dynamics of electrons in GaAs/AlxGal-xAs multiple quantum well structures. In our study of the effects of annealing on a short-period GaAs/ AlAs superlattice we have used Raman scattering …
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Magnetoconductance and Dynamic Phenomena in Single-Electron Transistors
… and the dominant source of resistance is the scattering of electrons due to small concentrations of impurity atoms in bulk metal. When the impurity atoms are not magnetic, such that there is no net electron spin, the zero temperature resistivity due to impurity scattering is proportional to …
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The Electrical Transport Study Of Graphene Nanoribbons And 2d Materials Beyond Graphene
… nanoribbons is largely limited by charged impurity scattering.</p> <p>We also report electrical characterization of monolayer molybdenum disulfide (MoS2) devices using a thin layer of polymer electrolyte consisting of poly (ethylene oxide) (PEO) and lithium perchlorate (LiClO4) as both a …
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Supercurrents in Restricted Geometries and Driven by Time-Dependent Electric Fields
… states in the normal metal is unaltered if the impurity self-energies are not taken into account while the coherence in the superconductor is always affected by the presence of the normal metal. Self-consistent calculations result in an impurity-induced proximity effect in the normal metal. This …
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