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 100 for “"Band-gaps"”.
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Thermally tunable band gaps in architected metamaterial structures
… characteristics such as relatively low and wide band gaps. These meta-structures have a fixed geometry and thus a fixed behavior, however applications that require structural vibration mitigation such as spacecraft and automotive components have variable vibration mitigation requirements over a …
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The nature of band gaps in ionic compounds and band structure aspects of spin transport
Contains fulltext : 145590.pdf (Publisher’s version ) (Open Access)
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Tunable mechanical bandgaps in elastic metamaterials: Patterning, straining, and spatiotemporal modulation
… a novel mechanism for evolving the elastic band gap structure in a bio-inspired composite through tension induced non-planar interfacial deformation. We show that band gaps emerge and may be tuned using externally applied tension forces in three example microstructures. Then we investigate …
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Exploring the Optical and Redox Properties of π-Conjugated Boron Difluoride Formazanate Dyes
… to modulate the frontier molecular orbitals and band gaps of these systems. The resulting materials are redox-active and exhibit rich optical properties including high molar absorptivities and low band gaps. Chapter 2 describes a series of acceptor-donor-acceptor compounds consisting of BF2 …
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Exploring for new photonic band gap structures
In the infinite set of possible photonic band gap structures there are no simple rules to serve as a guide in the search for optimal designs. The existence and characteristics of photonic band gaps depend on such factors as dielectric contrast, volume fraction, symmetry and connectivity of the …
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Engineering Band Structures in Correlated Oxides
… structure depends on N. We found the valence band structure systematically changes, as N decreases, from bulk like band gaps to interface modified band gaps. The temperature dependence of the derived Mn Jahn-Teller/Mott gap in large period superlattices is completely different from the small …
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Sonic Crystal Noise Barriers
… a selective sound attenuation in frequency bands called band gaps or stop bands related to the spacing and size of the cylinders. Theoretical studies using Plane Wave Expansion (PWE), Multiple Scattering Theory (MST) and Finite Element Method (FEM) have enabled study of the performance of SC …
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First principles modelling of tunnel field-effect transistors based on heterojunctions of strained Germanium/InGaAs alloys
… FET (TFET). The type of device depends on the band alignments at the heterojunction. For example, it determines if it can work as a TFET or a MOSFET. In turn, the band alignments depend on the atomistic details of the interface structure. <br/><br/>First-principles calculations were performed …
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Computational modelling of the electronic and structural properties of chalcopyrite-type semiconductors and platinum group metal chalcogenides
… is the design of materials with appropriate band gaps. Electronic structure calculations based on Density Functional Theory (DFT) have been extensively used to study and to describe such properties of many condensed matter systems. In this work, we have utilized DFT to study the electronic …
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Electronic band structure variations in photothermal catalytic materials
… and their interfaces. Yet, the electronic band structure of many of these materials under thermal expansion is under explored. In this study we calculate the electronic structures of a select group of sulfide semiconductors and their lattice thermal expansions, focusing on key parameters …
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Spectroscopic analysis of selected silicon ceramics
… energy scale to facilitate measurement of the band gap. Since previously measured band gaps are not well represented in literature, the measured band gaps were compared to values predicted using DFT calculations. The band gap values are in reasonable agreement to calculated values, but do not …
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Atomistic and ab initio prediction and optimization of thermoelectric and photovoltaic properties
… lattice thermal conductivities KL and electronic band gaps E,, which are relevant to thermoelectric and photovoltaic applications, respectively, and develop or modify computational tools for predicting and optimizing these properties. For lattice thermal conductivity, we study SiGe nanostructures, …
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Coordination and lonic compounds of benzamide and related molecules and metal halides
… spectroscopy (DRS) was employed to measure the band gaps of the series of isostructural, one-dimensional coordination polymers. These measurements indicated that the Cd analogues in this series have band gaps that place them in the category of electronic insulators. The Cu members of this series …
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Methods for Accurately Modeling Complex Materials
… theory (DFT) used for accurate treatment of band gaps in semiconductors, spin density functional theory with the inclusion of spin-orbit interaction to model nanomagnetic systems, and novel empirical potentials that reproduce ab-initio data at a fraction of the computational cost. We also …
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Semiconducting properties of the passive films on copper
… films show photovoltages under illumination. The band gaps of the anodic films and thermal oxides are similar to that of CuO (1.7 eV). The band gap of the film formed in CuSOi+ is close to that of Q12O (2.2 eV). The electron transfer between the passive electrodes and the redox couple shows …
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Topics in the theory of semiconductors: I. Novel semiconductors II. Uniaxial stress dependence of deep impurities
… 1, and 3 deal with the electronic energy band structures of novel semiconductors and chapter 4 deals with the uniaxial stress dependence of deep substitutional impurity levels in semiconductors. Chapter 1: The electronic energy band structure and deep substitutional impurity levels for …
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Optomechanical anisotropy in nanoengineered polymer photonic crystals
… is reflected in the structure of their photonic bands and symmetry breaking can result in the development of complete photonic band gaps, leading to enhanced optical properties. This can be difficult for self-assembled nanostructures, due to their restriction by fundamental principles to …
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Optical absorption measurements on silver halides in the ultraviolet and extreme ultraviolet energy ranges
… energy range, 3.5 to 240 electron volts. Band gaps have been estimated from the ultraviolet energy data and exciton binding energies. Comparison of ultraviolet structure and extreme ultraviolet structure, and measurements taken at different temperatures give evidence that in the high …
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Computational and experimental analyses and optimization of architectured materials
… failure mechanism. Additionally, the acoustic band structure and sound attenuation of three cellular materials based on Schwarz Primitive, Schoen IWP, and Neovius surfaces are studied using a finite element method. The acoustic properties of TPMS structures have many potential engineering …
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Unleashing the potential of ULPING: synthesis and property tuning of opto-electronic materials
… characterization showcased amplified band gaps across all materials, harmonizing with the newly formed nanostructures. This novel technique streamlines synthesis, reducing steps while advancing green fabrication of opto-electronic materials, signifying a significant stride in …
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