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 147 for “"Fermi level"”.
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Modelling of Berry phase and Fermi-level topologies for emergent quantum phenomena prediction in selected solid state systems
… Berry curvature, surface state spectra, and Fermi arc patterns via WannierTools. To probe QPTs in SrSi2, we employ the Quantum Lattice environment to simulate a renormalized graphene lattice, mapping analogies between external perturbations and topological responses in both systems.
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Layer disordering and aluminum-gallium interchange in aluminum-gallium arsenide - gallium-arsenide quantum well heterostructures
… the crystal surface-ambient interaction and the Fermi-level effect. We have investigated the crystal surface-ambient interaction by varying both the surface encapsulation condition (e.g., SiO$\sb2$-cap, Si$\sb3$N$\sb4$-cap) and the anneal ambient (As-rich, Ga-rich). The Fermi-level effect has …
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Effects of Substrate and Molecular Adsorption on Raman Scattering From Individual Single -Walled Carbon Nanotubes
… environment leads to charge transfer (and the Fermi level shift below the Dirac point) in metallic nanotubes while no significant effects of O2 adsorption are observed for semiconducting nanotubes from Raman scattering measurements. In metallic nanotubes, adsorption of O 2 is enhanced by the …
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Spectroscopic characterization of the near-surface electronic structure of surface-modified III-V semiconductors
… lattice, which are known to cause pinning of the Fermi energy level and an increase in the Schottky barrier in the semiconductor, can be passivated using inorganic sulfides. Although treatment with the inorganic sulfides is effective in reducing the surface recombination velocity, the loss of the …
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Electrical Response of Carbon Nanotubes Under Electrolyte
… electric field to emit optical phonons and the Fermi level lies near the band crossing point. The Fermi level dependent enhancements in noise amplitude have been correlated with Raman G-band broadening. These observations suggest that F optical phonons have dominant effects on the rise of …
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Band engineering of metal oxide heterostructures for catalysis applications
… electron richness (represented by the surface Fermi level) of the catalyst. A semi-empirical model was also developed to relate the Fermi level of oxide catalysts to their activity. Using these models, the quantitative variation of catalytic activity with the heterostructure parameters …
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Phase Stability In Cobalt-Based L12 Quaternary Intermetallics From Density Functional Theory
… of the pseudogap and number of states at the Fermi level. Charge density differences across the supercell were visualized to analyze changes in bonding behavior. The results indicate that substitutions of Ti, Ta, and Hf in place of the central W atom increase phase stability by lowering the …
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Evaluations of single walled carbon nanotubes using resonance Raman spectroscopy
… structure of SWNTs, and, at the single nanotube level, the spectra vary from tube to tube, depending on tube diameter and chirality, and on the energy of the van Hove singularity relative to E[laser]. In the second study, we present a theoretical method of predicting, to within a linear constant …
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Semi-Empirical Studies on Electronic Properties and Applications of Carbon Nanotubes
… geometry, field strength and position of the Fermi level. We find significant modification of the band structure at the strong field limit. Band gap opening/closing is predicted for metallic/semiconducting zigzag nanotubes, while armchair nanotubes remain metallic due to the high lattice …
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The Effect of Growth Method on GaN Films and Their Interfaces with CdTe and CdS
… conduction and valence band offsets, and Fermi level positions. These interface studies will help determine basic properties to see if these GaN films can be incorporated in a CdTe solar cell to improve its efficiency. It was determined that all the interfaces between the sputtered …
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Novel dopants for n-type doping of electron transport materials: cationic dyes and their bases
… devices as well. If we succeed in shifting the Fermi level towards the transport states, this could reduce ohmic losses, ease carrier injection from contacts and increase the built-in potential of Schottky- or pn-junctions.
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Nuclear Magnetic Resonance Studies of the High-Temperature Superconductors in the Normal and Superconducting States
… field dependence of the density of states at the Fermi level. This field dependence agrees with a recent prediction by Volovik that a superconductor with nodal lines in the superconducting gap can have quasiparticle excitations outside the vortex cores associated with the Doppler shift of the …
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Optical and Electronic Interactions at the Nanoscale
… dielectric constant) describing transport at the Fermi level, as expected for Fermi level changes near a mobility edge. Our measurements suggest that the localization length increases to significantly greater than the quantum dot diameter and further that application of gate bias decreases the …
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The electronic transport properties of undoped and doped arsenic triselenide
… of a multiple trapping transport model with trap levels E<sub>2</sub> (0.62eV) and E<sub>3</sub> (0.42eV) above the valence band edge.<br/><br/>Variation of the dispersion parameter with temperature in vitreous material supports the presence of structure at E<sub>2</sub> in the distribution of …
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Electronic and lattice vibrational properties of thorium hydrides
… large electronic density of states at the Fermi level suggests the possibility of occupied 5f electron states. By contrast, the dihydride of tporium was found to have a rather low density of states which presumab1y accounts for its lack of superconductivity. Anomalies in the heat capacities …
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Electronic structure, defect formation and passivation of 2D materials
… but the slope does not always equal because Fermi level pinning (FLP) arises. The chemical trend of FLP is investigated. Then we show that the pinning factor of Si can be tuned by inserting an oxide interlayer, which is important in the application to dopant-free Si solar cells. Apart from …
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Electrical contacts on two-dimensional transition metal dichalcogenide semiconductors
… However, unusually high contact resistance and Fermi level pinning have been observed due to damage at the metal-2D TMD interface. Studies have shown that van der Waals (vdW) contacts formed by dry transfer of graphene and metals can avoid damage to atomically thin TMDs caused by metal …
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The Effect of Pressure on The Height of The Schottky Barrier for Several Semiconductors (Diodes, Metal-Contacts)
… of the top of the valence band relative to the fermi level of the metal to the ionicity of the semiconductor. These measurements are compared to correlations of the change of the barrier height with the work function of the metal which have previously appeared in the literature.
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Surface and interface studies of compound semiconductors
… direction. The deconvoluted Sb-4d and Ga-3d core-level line shapes were used to construct a structural model for the surface. STM resolved the individual atomic dimers verifying the proposed model and showed partial disorder inherent on this surface. The interaction of the clean GaSb(lOO) surface …
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Single-electron transport and electron-phonon interactions in graphene heterostructured self-assembled molecular solid-state devices
… involving a single spin-degenerate energy level and one vibrational mode, is proposed. Statistical analysis is performed to study the spacing, and temperature-dependent measurements are carried out to search for phonon-absorption peaks. Negative differential conductance at the onset of …
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