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 64 for “"band alignment"”.
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Semiconductor electronic band alignment at heterojunctions of wurtzite aluminum nitride, gallium nitride, and indium nitride
In this thesis the band alignments for wurtzite (0001) heterojunctions of AlN, GaN, and InN semiconductors are measured by x-ray photoemission spectroscopy. The bands alignments are all found to be Type I, and the valence-band discontinuities are found to be:(UNFORMATTED TABLE OR EQUATION …
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First-Principles Study of Band Alignment and Electronic Structure at Metal/Oxide Interfaces: An Investigation of Dielectric Breakdown
… trigger the dielectric breakdown. A classical band alignment method, the Van de Walle method, is applied to the case study of the Al/crystal-SiO2 (Al/c-SiO2) interface. Point defects, such as oxygen vacancy (VO) and hydrogen impurity (IH), are introduced into the Al/c-SiO2 interface to study …
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Interband quantum tunneling at the band-edges in III-V semiconductor heterojunctions for low-power logic and detectors
This thesis explores interband tunneling in semiconductor heterojunctions where a density-of-states switching mechanism can be used to sharply modulate the junction conductance using small applied voltages via alignment and misalignment of the band-edges. Such a mechanism is useful for the pursuit …
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Analysis of and process development for high-frequency indium gallium phosphide/gallium arsenide heterojunction bipolar transistors
… a potential replacement for AlGaAs as the wide band gap emitter material. These properties include the availability of highly selective etches, an energy band alignment favorable for high injection efficiency devices, and the absence of DX centers.
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Development of the Visible Light Photon Counter for Applications in Quantum Information Science
… that is wafer-fusion bonded to the VLPC. The band alignment of the resulting InGaAs/Si heterojunction is measured and shows a large discontinuity in the valence band that impedes carrier transport at the interface. A ultra-high vacuum wafer-bonding system was developed to understand the impact …
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Electronic band structure of III-V quantum dots using tight-binding and the k.p approximation
… moments based tight-binding model for electronic band structure calculations are implemented for several cases relating to quantum dot nanostructures where various mechanical models are investigated. First, a comparison is made between the two for an equivalent sized ellipsoidal InAs/GaAs quantum …
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Large-Scale Atomistic Simulations of Complex and Functional Properties of Ferroic Materials
… the combined HEff and LS3DF method to study how band gap and band alignment evolves along the path from a polar-toroidal to an electrical skyrmion state. Temperature control of the vortex provides substantially larger range of control of bandgap and band alignment than field control of the …
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Exploring and exploiting charge-carrier confinement in semiconductor nanostructures : heterodimensionality in sub-monolayer InAs in GaAs and photoelectrolysis using type-II heterojunctions
… by single-particle effective-mass and eight-band k · p calculations, which show heterodimensional confinement is probable for a large variation in In content. SML vertical-cavity surface-emitting lasers (VCSELs) — which prove to be one of the most promising candidates for datacoms …
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Electronic structure and optical properties of sb-based self-assembled quantum dots for the mid-infrared range
… levels and densities of states. Due to their band structure, QD systems show significant advantages as active regions in laser cavities, both in term of lower threshold current densities and better thermal behaviour. The most studied system beingInAs/GaAs system but the antimonide-based …
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Photothermal and Photoelectric Effects in Lithium-Ion Batteries: Mechanistic Insights and Performance Enhancement
… Furthermore, an in-depth examination of band alignment between the photoelectrode and counter electrode highlighted the mechanisms of charge transport, differentiating between photothermal and photoelectric effects through ultraviolet photoelectron spectroscopy (UPS) and UV-Vis …
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Design, Fabrication, and Modeling of Indium Phosphide Double-Heterojunction Bipolar Transistors With Sub-Millimeter Wave Cutoff Frequency
… are studied with the goal of improving device bandwidth. The cutoff frequencies of double-heterojunction transistors are extended as high as 690 GHz while maintaining an off-state breakdown voltage greater than 3 V by using the InP/GaAsSb material system with a type-II energy band alignment. …
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Temperature effects on the electronic properties of lead telluride (PbTe) and the influence of nano-size precipitates on the performance of thermoelectric materials. (SrTe precipitates in PbTe bulk material)
… mobility was studied by finding out the relative alignment of energy bands at the semiconductor heterojunction. The crystal shape of the SrTe precipitates in the PbTe host matrix was evaluated from the interface energies using the Wulffman construction. We also attempted to develop a relation …
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Theory and experiments of type-II superlattice infrared photodetectors
… interest in the past few decades. The type-II band alignment in this material system provides a long cutoff wavelength and a wide optical tunable range in the mid-infrared regime. Photodetectors based on type-II superlattices are theoretically predicted to surpass the performance of those based …
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First Principles Investigations of Solid-Solid Interfaces in Lithium Battery Materials
… measure of interfaces and analysis of the band alignment between interface materials indicate multiple factors which may be predictors of interface stability, an important property of electrolyte systems.
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Alloyed heterojunction nanorods and their applications
… material while maintaining proper energy band alignment in the heterostructure, with the goal of extending the emission range to green or even blue. I developed a new two-step cation exchange process to alloy the nanorods with Zn while preserving their shape. With subsequent shell growth, …
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Toward efficient and stable quantum dot solar cells : design and characterization
… the solution-processability and a tunable energy bandgap that covers the optimal bandgap range for single and multi-junction solar cells. However, despite rapid progress, previous QD solar cells still show unsatisfactory efficiency and stability. In this thesis work, room-temperature …
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Band Offset Measurements of ε-(InxGa1-x)2O3/AlN using X-ray Photoelectron Spectroscopy
… hold significant promise due to their ultra-wide band gap, tunable polarization properties, and optimized spectral response. In this regard, the ε-(In0.15Ga0.85)2O3 /AlN heterojunction has significant potential for high-performance optoelectronic devices, particularly in extreme environments, due …
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Hot electron injection effect and improved linearity in type-I/II DHBT for millimeter-wave mixed signal circuit applications
… material system with a Type-I/II energy band alignment. Chapter 1 of this work gives a brief overview of the motivation to conduct this research and an introduction to other relevant work. Scaling theory, structure design and previous work done at the University of Illinois at …
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Tunable Electronic Excitations in Hybrid Organic-Inorganic Materials: Ground-State and Many-Body Perturbation Approaches
… including ease of fabrication, suitable band gap, large absorption, high charge carrier mobility, etc. However, the structure and properties of their two-dimensional (2D) counterparts, especially those with complex organic components, are not understood as deeply as the 3D HOIPs. Due to …
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Defect engineering of cuprous oxide thin-films for photovoltaic applications
… buffer layer is developed to mitigate non-ideal band alignment and interfacial defect-assisted recombination in Cu₂O - zinc oxide (ZnO) heterojunction devices. Reduced interfacial recombination is demonstrated by incorporating a 5-nm-thick buffer layer in the device. Finally, I propose a …
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