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Full-Text Articles in Physical Sciences and Mathematics
Heat, Charge And Spin Transport Of Thin Film Nanostructures, Devin John Wesenberg
Heat, Charge And Spin Transport Of Thin Film Nanostructures, Devin John Wesenberg
Electronic Theses and Dissertations
Understanding of fundamental physics of transport properties in thin film nanostructures is crucial for application in spintronic, spin caloritronics and thermoelectric applications. Much of the difficulty in the understanding stems from the measurement itself. In this dissertation I present our thermal isolation platform that is primarily used for detection of thermally induced effects in a wide variety of materials. We can accurately and precisely produce in-plane thermal gradients in these membranes, allowing for thin film measurements on 2-D structures. First, we look at thermoelectric enhancements of doped semiconducting single-walled carbon nanotube thin films. We use the Wiedemann-Franz law to calculate …
Dynamics Of Polyelectrolyte Adsorption On Surfaces: Applications In The Detection Of Iron In Water, Madhira N. Gammana
Dynamics Of Polyelectrolyte Adsorption On Surfaces: Applications In The Detection Of Iron In Water, Madhira N. Gammana
Electronic Theses and Dissertations
Layer by layer (LbL) self assembly is a simple multilayer thin (nanometer scale) film fabricating technique. The mechanism of film growth remains a topic of much controversy. For example, several models have been proposed to explain the origin of linear and exponential film growth that are attributed to differences in the dynamic processes that occur at the molecular level during film formation. The problem is that there are no methods that directly measure the dynamics of polymer formation during LbL film formation. In this thesis, I describe the essential elements of an ATR-IR spectroscopic method that was developed to enable …
Nanoscale Thermoelectrics: A Study Of The Absolute Seebeck Coefficient Of Thin Films, Sarah J. Mason
Nanoscale Thermoelectrics: A Study Of The Absolute Seebeck Coefficient Of Thin Films, Sarah J. Mason
Electronic Theses and Dissertations
The worlds demand for energy is ever increasing. Likewise, the environmental impact of climate change due generating that energy through combustion of fossil fuels is increasingly alarming. Due to these factors new sources of renewable energies are constantly being sought out. Thermoelectric devices have the ability to generate clean, renewable, energy out of waste heat. However promising that is, their inefficiency severely inhibits applicability and practical use. The usefulness of a thermoelectric material increases with the dimensionless quantity, ZT, where, Z = S2σ/κ, and S, σ, and κ are the Seebeck coefficient and electrical and thermal …
The Impact Of Growth Conditions On Cubic Znmgo Ultraviolet Sensors, Ryan Boutwell
The Impact Of Growth Conditions On Cubic Znmgo Ultraviolet Sensors, Ryan Boutwell
Electronic Theses and Dissertations
Cubic Zn1-xMgxO (c-Zn1-xMgxO) thin films have opened the deep ultraviolet (DUV) spectrum to exploration by oxide optoelectronic devices. These extraordinary films are readily wet-etch-able, have inversion symmetric lattices, and are made of common and safe constituents. They also host a number of new exciting experimental and theoretical challenges. Here, the relation between growth conditions of the c-Zn1-xMgxO film and performance of fabricated ultraviolet (UV) sensors is investigated. Plasma-Enhanced Molecular Beam Epitaxy was used to grow Zn1-xMgxO thin films and formation conditions were explored by varying the growth temperature, Mg source flux, oxygen flow rate, and radio-frequency (RF) power coupled into …
Metal Blacks As Scattering Centers To Increase The Efficiency Of Thin Film Solar Cells, Deep R. Panjwani
Metal Blacks As Scattering Centers To Increase The Efficiency Of Thin Film Solar Cells, Deep R. Panjwani
Electronic Theses and Dissertations
Metal nano particles are investigated as scattering centers on front surface of thin-film solar cells to improve efficiency. The principle is that scattering, which is enhanced near the plasmon resonance frequency of the particle and depends on particle size, increases the effective optical path length of incident light, leading to more light absorption in active layer of thin film solar cell. The particular types of particles investigated here are known as "metal-black", well known as an IR absorber for bolometric infrared detectors. Gold-black was deposited on commercial thin-film solar cells using a thermal evaporator in a nitrogen ambient at pressures …
Measurement Of Thermoelectric Properties Of Amorphous Silicon Based Thin Films, Rubina Sultan
Measurement Of Thermoelectric Properties Of Amorphous Silicon Based Thin Films, Rubina Sultan
Electronic Theses and Dissertations
It is important to understand thermal transport behavior in materials for technological and fundamental physics applications. Many efforts have been made in the past for explaining thermal conduction in solids. It has been observed that thermal transport properties may change with reducing size of the sample, especially as sample size approaches the nanoscale regime. The deviation in these properties, mainly in thermal conductivity, may change the choice of the material for different applications such as thermoelectricity. Thermoelectric materials are a possible source of sustainable energy and can play an important role in the fight against the present energy crisis. Recently, …
Modification Of Semi-Metal Oxide And Metal Oxide Powders By Atomic Layer Deposition Of Thin Films, Mark Q. Snyder
Modification Of Semi-Metal Oxide And Metal Oxide Powders By Atomic Layer Deposition Of Thin Films, Mark Q. Snyder
Electronic Theses and Dissertations
This work describes two methods of modifying, and the subsequent characterizing of, oxide nanopowders. The first method, atomic layer deposition, or ALD, is a series of surface-limited reactions that are repeated to deposit a thin, inorganic film on the surface of the nanopowder. Deposition of a thin film is a useful method to alter the surface properties of a material while retaining its bulk properties. Part of this thesis concerns the understanding of the growth mechanism of thin film titanium nitride (a material known for thermal and chemical stability as well as electronic conductivity) on silica through the ALD process. …
Reactions Of Alcohols And Organophosphonates On Tungsten Trioxide Epitaxial Films, Shuguo Ma
Reactions Of Alcohols And Organophosphonates On Tungsten Trioxide Epitaxial Films, Shuguo Ma
Electronic Theses and Dissertations
The adsorption, diffusion, reactions, and desorption of water, alcohols, ethers, and an organophosphonate were studied using calibrated thermal desorption spectroscopy (CTDS) on thin film WO3(OOl) surfaces grown epitaxially on a single crystal α- Al2O3(li02) (sapphire) substrate. The studies were conducted on oxidized and reduced surfaces, which were characterized by x-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The desorption spectra for molecular desorption of all of these molecules shifted to lower temperature with increasing coverage, and had overlapping tails on the high temperature side. Monte Carlo simulations show that this typical desorption shape …
Stabilization Of Rutile-Related Thin Film On Tio2 Substrates, Youngnam Cho
Stabilization Of Rutile-Related Thin Film On Tio2 Substrates, Youngnam Cho
Electronic Theses and Dissertations
Conducting metal oxide thin films are of broad interest because they have a wide variety of magnetic and electronic properties. Materials exist that range from superconducting to insulating, are ferromagnetic and are ferroelectric. These properties make thin conducting oxide films attractive for many industrial applications. A class of metal oxides exists that adapt the rutile crystal structure; the structure of the mineral rutile, TiO2. These metal oxides have the general formula MO2 where M is a metal cation of valence +4. Metal oxides crystallizing in the rutile structure also display a wide variety of physical properties. The …
Use Of An Epitaxial Baf2 Buffer Layer On Silicon To Control W03 Thin Film Growth, Luke D. Doucette
Use Of An Epitaxial Baf2 Buffer Layer On Silicon To Control W03 Thin Film Growth, Luke D. Doucette
Electronic Theses and Dissertations
The electronic and mechanical properties of tungsten trioxide (W03) thin films have been successfully utilized in both surface acoustic wave and chemiresistive microsensor devices for the detection of certain gas-phase species. A critical material aspect that can affect microsensor performance is the type and degree of crystallization within the sensing film. However, the inclusion of this added dimension into a thin film limits the number of viable substrates for which heteroepitaxy may be realized. For W03, this constraint has restricted its usage as a sensing material to being primarily coupled with sapphire substrates. Not only does sapphire promote structured film …