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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 …

Synthesis And Characterization Of Kesterite Cu2znsns4 (Czts) Thin Films For Solar Cell Application, Mohamed M.A. Abusnina

Electronic Theses and Dissertations

The quaternary compound Cu₂ZnSnS₄ (CZTS) gained considerable attention in the last decade due to its potential as an active-layer semiconductor for low-cost thin-film solar cells. The material is composed of nontoxic and Earth-abundant constituents, has optical properties suitable for photovoltaic application, and can be synthesized using a wide variety of methods.

Polycrystalline CZTS was grown in this work using vacuum-based deposition to first deposit metal films (precursors) of Cu, Zn, and Sn. In a subsequent step, the precursors underwent an annealing treatment in sulfur vapor environment (sulfurization) to form CZTS. Using sputtering, a physical vapor deposition (PVD) …

Development Of A Thin-Film Porous-Microelectrode Array (P-Mea) For Electrical Stimulation Of Engineered Cardiac Tissue., Hiren Vrajlal Trada 1977-

Electronic Theses and Dissertations

Electrical stimulation has been increasingly used by research groups to enhance and increase maturation of cells in an engineered cardiac tissue (ECT). Current methods are based on using off-the-shelf wires or electrodes to deliver a stimulus voltage to the in-vitro tissue in culture medium. A major issue with this approach is the generation of byproducts in the medium due to the voltage levels required, which are typically in the range of 5V-10V. No solution currently exists that can accomplish electrical stimulation of cells in an ECT at a low voltage level. Therefore, in this study a novel, porous, thinfilm, microelectrode …

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

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 …

Investigation On Electrical Properties Of Rf Sputtered Deposited Bcn Thin Films, Adithya Prakash

Electronic Theses and Dissertations

The ever increasing advancements in semiconductor technology and continuous scaling of CMOS devices mandate the need for new dielectric materials with low-k values. The interconnect delay can be reduced not only by the resistance of the conductor but also by decreasing the capacitance of dielectric layer. Also cross-talk is a major issue faced by semiconductor industry due to high value of k of the inter-dielectric layer (IDL) in a multilevel wiring scheme in Si ultra large scale integrated circuit (ULSI) devices. In order to reduce the time delay, it is necessary to introduce a wiring metal with low resistivity and …

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 …

Atomistic Simulations To Micro-Mechanisms Of Adhesion In Automotive Applications, Fatih Gurcag Sen

Electronic Theses and Dissertations

This study aimed at depicting atomistic and microstructural aspects of adhesion and friction that appear in different automotive applications and manufacturing processes using atomistic simulations coupled with tribological tests and surface characterization experiments. Thin films that form at the contact interfaces due to chemical reactions and coatings that are developed to mitigate or enhance adhesion were studied in detail. The adhesion and friction experiments conducted on diamond-like carbon (DLC) coatings against Al indicated that F incorporation into DLC decreased the coefficient of friction (COF) by 30% -with respect to H-DLC that is known to have low COF and anti-adhesion properties …

Tuning The Bandgap Of An Amorphous Sputtered Germanium Photovoltaic Cell., Bryon Staebler 1979-

Electronic Theses and Dissertations

Microfabricated planar solar cells with an active solar collection area of 0.04cm2 were fabricated on n-type silicon wafers to test the viability of sputtered amorphous thin film photovoltaics for potential use in amorphous multijunction cells or inexpensive laser detectors. Several variants based on the same photovoltaic cell design were produced using amorphous silicon, amorphous germanium, and amorphous germanium-tin to explore band gap depression phenomenon in amorphous thin films that had been previously described in crystalline germanium-tin and germanium-silicon-tin alloys. UV/VIS spectroscopy and Tauc Plot band gap analysis indicated that tin inclusion led to band gap depression of 0.046 eV for …

Investigation Of Reactively Sputtered Boron Carbon Nitride Thin Films, Vinit O. Todi

Electronic Theses and Dissertations

Research efforts have been focused in the development of hard and wear resistant coatings over the last few decades. These protective coatings find applications in the industry such as cutting tools, automobile and machine part etc. Various ceramic thin films like TiN, TiAlN, TiC, SiC and diamond-like carbon (DLC) are examples of the films used in above applications. However, increasing technological and industrial demands request thin films with more complicated and advanced properties. For this purpose, B-C-N ternary system which is based on carbon, boron and nitrogen which exhibit exceptional properties and attract much attention from mechanical, optical and electronic …

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 …

Correlation Between Preparation Parameters And Properties Of Molybdenum Back Contact Layer For Cigs Thin Film Solar Cells, Eigo Takahashi

Electronic Theses and Dissertations

Molybdenum (Mo) thin film back contact layers for thin film CuIn(1-x)GaxSe2 (CIGS) solar cells were deposited onto soda lime glass substrates using a direct current (DC) planar magnetron sputtering deposition technique. Requirements for the Mo thin film as a back contact layer for CIGS solar cells are various. Sheet resistance, contact resistance to the CIGS absorber, optical reflectance, surface morphology, and adhesion to the glass substrate are the most important properties that the Mo thin film back contact layer must satisfy. Experiments were carried out under various combinations of sputtering power and working gas pressure, for it is well known …

Optimization Of Process Parameters For Reduced Thickness Cigses Thin Film Solar Cells, Shirish A. Pethe

Electronic Theses and Dissertations

With the advent of the 21st century, one of the serious problems facing mankind is harmful effects of global warming. Add to that the ever increasing cost of fuel and the importance of development of clean energy resources as alternative to fossil fuel has becomes one of the prime and pressing challenges for modern science and technology in the 21st century. Recent studies have shown that energy related sources account for 50% of the total emission of carbon dioxide in the atmosphere. All research activities are focused on developing various technologies that are capable of converting sunlight into electricity with …

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, …

Heat Transfer In Multi-Layer Energetic Nanofilm On Composites Substrate, Navid Amini Manesh

Electronic Theses and Dissertations

The main purpose of this work is to find a physical and numerical description related to the reaction of the multilayer nano energetic material (nEM) in dense film. Energy density of nEM is much higher than the conventional energetic material; therefore, nEM finds more applications in propulsions, thermal batteries, material synthesis, nano igniters, waste disposals, and power generations. The reaction model of a multilayer nEM in a dense film of aluminum and copper oxide deposits on a composite substrate of silica/silicon is studied and solved in different stages. The two main interests in this study are propagation speed and maximum …

Experimental Characterization And Modeling Of Isothermal And Nonisothermal Physical Aging In Glassy Polymer Films., Yunlong Guo 1977-

Electronic Theses and Dissertations

Fiber-reinforced polymer matrix composites (PMCs) using high-temperature thermoplastics as the matrix material represent a lightweight design solution for applications above 250°F. This is often required for aircraft structures subjected to supersonic airflows. While thermoplastic matrix PMCs may be successfully designed for such temperatures, they generally exhibit a time-dependent material response which must be well understood for successful design. One important aspect of this response is physical aging, which causes the viscoelastic behavior of amorphous polymers below their glass transition temperature to change with time. While isothermal physical aging has been extensively studied, physical aging during a varying temperature history has …

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. …

Photocatalytic Oxidation Of Carbon Monoxide Using Sputter Deposited Molybdenum Oxide Thin Films On A Silicon Dioxide Substrate, Donald Bragg

Electronic Theses and Dissertations

CO contamination is common in hydrogen extraction processes. Proton exchange membrane fuel cells need a source of hydrogen containing less than 10ppm of CO to avoid the irreversible poisoning of the fuel cell’s platinum anode. Platinum metal is commonly used as a catalyst for the purification of hydrogen gas. An effort has been put forth to replace the expensive platinum catalyst with a less expensive alternative. Photocatalytically active metal oxide semiconductors have shown promise as less expensive alternatives to platinum for redox reactions such as the oxidation of CO. This research studies a MoO3 sputter deposited thin film on a …

Near Room Temperature Self-Assembly Of Nanostructures By Reaction Of Gallium With Metal Thin Films., Mehdi M. Yazdanpanah 1975-

Electronic Theses and Dissertations

Liquid gallium (Ga) spontaneously alloys with thin films of metals such as Ag, Au, Pt Al, and Cu at near or even below room temperature resulting in rapid self-assembly of nanostructures. In this dissertation, studies of the formation of these nanostructures are reported together with application of the processes towards device fabrication. Ag 2 Ga needles, CoGa 3 rods, and Ga 6 Pt plates self-assemble at room temperature at the interface of Ga and thin films of Ag Co, and Pt. The Ag 2 Ga needles orient nearly vertical to the interface which suggests that an individual needle can be …

Thermal Conductivity Measurement Of Thin Film Of Carbon Swnt Using The 3w Technique., Anton Nickolaevich Sidorov 1981-

Electronic Theses and Dissertations

We have measured the temperature-dependent thermal conductivity, K(T) of single walled carbon nanotubes from 300 K to 8 K by 3w methods. K(T) exhibits linear temperature dependence in the entire temperature range. Our results are in good agreement with the results obtained by Hone et al. using a standard steady state technique. Also we measured the temperature-dependent thermal conductivity K(T) of quartz and SiO2 in the same temperature range (300 K to 8 K) as a standardization tool. Our technique shows promise for the thermal conductivity measurements of many nanostructures with slight modifications.

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 …

Platinum/Silica Thin Films By Chemical Vapor Deposition, Tyler Philip Martin

Electronic Theses and Dissertations

Composite thin films consisting of platinum and silica (SiO)₂ have been fabricated by chemical vapor deposition (CVD). These films were studied for possible future use in enhancing the selectivity of sensors for the chemical warfare agent sarin. Chemical vapor deposition is a thin film growth technique in which precursor molecules are carried into a reactor and decomposed, often at high temperature, to produce a thin solid film. A new cold wall CVD reactor was built for this work. The platinum precursor used in this work was platinum acetylacetonate [Pt(acac)₂] and the silica precursor was tetraethoxysilane (TEOS). It …

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

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 …

Reactively Sputter-Deposited Titanium Oxide And Barium Silicon Titanate Thin Films., Toru Yamashita

Electronic Theses and Dissertations

No abstract provided.