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 “"density of states (DOS)"”.
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Electronic structure and optical properties of layered ternary transition-metal carbides and nitrides
The electronic structure and optical properties of Ti3AC2 (A=Al, Si, Ge), Ti2AC (A=Al, Ga, In; Si, Ge, Sn; P, As; S), Ti2AlN, M2AlC (M=V, Nb, Cr) and Tan+1AlCn (n=1~4) have been studied using first-principles orthogonalized linear combination of atomic orbitals (OLCAO) method. These layered ternary …
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Low-Frequency Emission Enhancement by Resonant Acoustic Metamaterials
… enhancement and controlling the directivity of an acoustic source is however restricted to the properties of the source. In particular, the size of the source, in comparison with the wavelength of the sound, plays a very dominant role in determining the quality of the emitted acoustic wave. …
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Theoretical Study of Electron Transport and Trapping in Solvated Titanium Dioxide Nanoparticles
This thesis consists of two parts of work: the advances on the efficient and robust implementation of our quantum chemistry program Jaguar for large DFT calculations, and theoretical modeling of electron transport and trapping in solvated TiO_2 nanoparticles. In first half, We implemented an …
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Single particle spectrum of the two dimensional electron gas
… However, despite their importance in the study of highly correlated systems, two-dimensional systems (2DES) have proven difficult to probe spectroscopically. Typical energy scales are on the order of a millielectron volt (meV), requiring high resolution, while correlated states of interest, such …
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Thermoelectric Properties and Transport of Semicrystalline Conjugated Polymer and Single-Wall Carbon Nanotube Composites
… years, aiming to combine the high power factor of CNT networks and the low thermal conductivity of polymer matrix. Many attempts have been made on achieving the electron-crystal-phonon-glass concept and the simultaneous increase of electrical conductivity and the Seebeck coefficient. However, …
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Deriving The Density Of States For Granular Contact Forces
The density of single grain states in static granular packings is derived from first principles for an idealized yet fundamental case. This produces the distribution of contact forces P_f(f) in the packing. Because there has been some controversy in the published literature over the exact form of …
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Light scattering studies of phonon anomalies and superconductivity in A15 compounds
Light scattering studies of phonon anomalies and superconductivity in A15 compounds and Nb, V, and Ta are presented. The experimental methods included one-and two-phonon and electronic Raman scattering and Brillouin scattering from Surface Acoustic Waves (SAWs). The Eg optic phonon in V3Si, Nb~n, …
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Angle resolved photoemission studies of silver bromide
… data on randomly oriented thick films of metallic silver, thin films of randomly oriented polycrystalline AgBr and AgBri, and epitaxially grown AgBr on an Ag ( 111) single crystal. The experiments on the randomly oriented samples were concerned with obtaining the correct sample …
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Tunneling spectroscopy of the two-dimensional electron gas
We measure the single particle density of states (DOS) of a two-dimensional electron system (2DES) in a GaAs/AlGaAs heterostructure. Using a technique that we call "Time Domain Capacitance Spectroscopy" (TDCS), we measure the complete current-voltage characteristics for tunneling into the 2DES …
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Polycrystalline Silicon TFTs for Large Area Electronic Application
… under the on-state condition and optimisation of blocking capability, transient switching characteristics. Significant improvements in the device performances have been demonstrated by using novel device structures. In addition, the search for a higher blocking capability is a constant aim …
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Influence of Electronic Structure and Lattice Dynamics on Oxygen Ion Transport in Solid-State Ionic Conductors
… pre-exponential factor in the Arrhenius equation of conductivity. However, our understanding of the fundamental processes in oxygen ion transport and methods to improve oxygen ion conductivity remain limited. This thesis focuses on understanding the fundamental mechanisms that regulate oxygen ion …
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Ανάλυση και εφαρμογή σε πειραματικά δεδομένα της μεθόδου του διαμορφωμένου φωτορεύματος, για τον προσδιορισμό των παραμέτρων της πυκνότητας καταστάσεων ημιαγωγών, κατάλληλων για φωτοηλεκτρονικές εφαρμογές
Στην διατριβή αυτή μελετήθηκαν και εξακριβώθηκαν θεωρητικά όλες οι φυσικές διεργασίες που υπεισέρχονται στις μετρήσεις του διαμορφωμένου φωτορεύματος. Με βάση αυτές δείξαμε ότι μπορούμε να εξάγουμε όλες τις πιθανές διεργασίες παγίδευσης και επανασύνδεσης σε διάφορες κατηγορίες ανόργανων ημιαγωγών. …
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Carrier mobility of downscaled amorphous semiconductors exemplified by hydrogenated amorphous silicon
… electronics that collaboratively build many of today’s and the next-generation’s Internet of Things (IoT) facilities. Amorphous semiconductors are among the most favoured channel semiconductors in TFTs because of their irreplaceable merits such as large-area uniformity, low cost and low …
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Machine Learning for Phonon Thermal Transport
… generation, transport, conversion, and storage of energy are essential to support our modern society and combat global climate change. As one of the major energy carriers, phonons play an indispensable role in various energy-related processes. The past decades witnessed continuous development in …
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Reactive Sputtering Deposition and Characterization of Zinc Nitride and Oxy-Nitride Films for Electronic and Photovoltaic Applications
… dissertation presents a study on the fabrication of zinc nitride and zinc oxy-nitride films, and related hetero-structures on glass, silicon and other substrates. The goals of this study include gaining fundamental understanding on the electrical and optical properties, the chemical-bonding states …
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Charge and Thermoelectric Transport in Semicrystalline Conjugated Polymers and Single-Walled Carbon Nanotube Networks
… In the past two decades the development of high-mobility donor-acceptor copolymers outperforming amorphous silicon, employed in commercial display technologies, and the ability to tune the diameter distribution in SWCNT networks via selective dispersion with conjugated polymers and other …
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Cobalt-based Heusler compounds in magnetic tunnel junctions
Spintronic devices have attracted a lot of attention in recent years due to possible new applications, e.g., a magnetic random access memory (MRAM), logic and sensors. The spin of the electrons is used as an additional degree of freedom in contrast to common electronic devices. The main constituent …
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Metallic Ground State of Functionalized Carbon Nanotubes
… The SWCNT are arranged in bundles of some ten nanotubes with a random distribution of semiconducting and metallic tubes. They are thus one-dimensional objects embedded in a three-dimensional arrangement, the bundles. In this thesis, the metallic ground state of one-dimensional (1D) …
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Optimization of Materials for Magnetic Refrigeration and Thermomagnetic Power Generation
… harvesting; and another focusing on methods of materials discovery for refrigeration purposes. Thermomagnetic power generation (TMG) is the process by which magnetic flux, which comes from a temperature-driven change of magnetization, is converted into usable energy.</p> <p>The first part of …
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Time and frequency resolved photoconductivity studies on amorphous semiconductors
… in a complementary fashion to investigate the density of states (DOS) and associated trapping and recombination parameters of amorphous semiconductors. The solution of the linearised multiple trapping rate equations is straightforward in the frequency domain, and it is simple to invert the …
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