Physics Commons^™

Investigation Of Phonon Polaritons In An Hbn Gan Heterostructure, Catherine G. O'Hearn

Graduate Theses, Dissertations, and Problem Reports

There have been many great advances in the generation and manipulation of optics in the visible and near infrared (IR) range over the past decade. This is largely due to plasmonic enhancement, which has led to new technology in biosensing and molecule detection, solid-state lighting, and solar energy harvesting. The field of plasmonics uses quanta of plasma oscillations, plasmons, formed from the interaction between electromagnetic radiation and free electrons to enhance optical near field magnitudes. However, there is still a large region of the electromagnetic spectrum, covering the mid-infrared (MIR) and terahertz (THz) regions, ranging from 3 μm to 1 …

Experimental And Computational Exploration Of The Dilute Magnetic Delafossite Cual1-Xfexo2 Alloys, Mina Aziziha

Graduate Theses, Dissertations, and Problem Reports

CuAlO₂ is among several ternary delafossites, which is a rare p-type semiconductor with potential applications as a transparent conductive oxide, photocatalyst, and spintronics when doped with transition metal ions. Reported in this thesis are results from our investigations of CuAl_1-xFe_xO₂ (x = 0 to1) with a focus on the x-dependence of structural, magnetic, vibrational, optical properties, and the role of defects and impurities. Samples are prepared by solid-state reactions.

We performed a complete study of magnetic properties to investigate the possibility of room temperature ferromagnetic alloys, which are used in …

Synthesis Of Graphene Using Plasma Etching And Atmospheric Pressure Annealing: Process And Sensor Development, Andrew Robert Graves

Graduate Theses, Dissertations, and Problem Reports

Having been theorized in 1947, it was not until 2004 that graphene was first isolated. In the years since its isolation, graphene has been the subject of intense, world-wide study due to its incredibly diverse array of useful properties. Even though many billions of dollars have been spent on its development, graphene has yet to break out of the laboratory and penetrate mainstream industrial applications markets. This is because graphene faces a ‘grand challenge.’ Simply put, there is currently no method of manufacturing high-quality graphene on the industrial scale. This grand challenge looms particularly large for electronic applications where the …

Control Of Charged Particle Dynamics And Electron Power Absorption Dynamics Utilizing Voltage Waveform Tailoring In Capacitively Driven Radio-Frequency Plasmas, Steven W. Brandt

Graduate Theses, Dissertations, and Problem Reports

In this work, experimental measurements and analysis of numerical simulations are performed for capacitively coupled plasmas driven by tailored voltage waveforms under conditions which examine complicating factors present in industrial processes, including the influence of resonance effects, electronegative gases or gas mixtures, and plasma-surface interactions at a changing plasma-surface interface. Furthermore, the influence of different tailored voltage waveforms on the spatio-temporal electron power absorption, the generation of a DC self-bias, and on process relevant plasma parameters like ion energy distribution functions is investigated to provide a more complete understanding of the underlying fundamental plasma physics responsible for sustaining the discharge. …

Ultrafast Optical Properties Of La0.7sr0.3mno3 Thin Films, Saeed Yousefi Sarraf

Graduate Theses, Dissertations, and Problem Reports

Thin film solids often exhibit different physical properties in the ultra-thin regime. Enhancement of surface to bulk ratio results in the domination of surface/interface related phenomena such as surface recombination. Moreover, in the ultra-thin regime, quantum size and quantum confinement effects can alter the band gap of the system and constrain the strain wave propagation in the thin film. Ultrafast properties of solids can also be drastically altered in the ultra-thin regime due to the aforementioned phenomena. Experimentally, observation of these phenomena is challenging due to the insufficient material to absorb and interact with the electromagnetic wave. This dissertation addresses …

Interpretations Of Bicoherence In Space & Lab Plasma Dynamics, Gregory Allen Riggs

Graduate Theses, Dissertations, and Problem Reports

The application of bicoherence analysis to plasma research, particularly in non-linear, coupled-wave regimes, has thus far been significantly belied by poor resolution in time, and/or outright destruction of frequency information. Though the typical power spectrum cloaks the phase-coherency between frequencies, Fourier transforms of higher-order convolutions provide an n-dimensional spectrum which is adept at elucidating n-wave phase coherence. As such, this investigation focuses on the utility of the normalized bispectrum for detection of wave-wave coupling in general, with emphasis on distinct implications within the scope of non-linear plasma physics. Interpretations of bicoherent features are given for time series from …

On Demand Nanoscale Phase Manipulation Of Vanadium Dioxide By Scanning Probe Lithography, Dustin Schrecongost

Graduate Theses, Dissertations, and Problem Reports

This dissertation focuses on nanoscale phase manipulations of Vanadium Dioxide. Nanoscale control of material properties is a current obstacle for the next generation of optoelectronic and photonic devices. Vanadium Dioxide is a strongly correlated material with an insulator-metal phase transition at approximately 345 K that generates dramatic electronic and optical property changes. However, the development of industry device application based on this phenomenon has been limited thus far due to the macroscopic scale and the volatile nature of the phase transition. In this work these limitations are assessed and circumvented.

A home-built, variable temperature, scanning near-field optical microscope was engineered …