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ASU Electronic Theses and Dissertations


This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.

In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.

Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.


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Date Range
2012 2016


A series of Molybdenum-Copper bilayers were studied for use in 120mK superconducting transition edge sensors for spectrometer applications. The Transition temperature (T<sub>C</sub>) was tuned to the desired temperature using the proximity effect, by adjusting the thickness of a normal copper layer in direct contact with the superconducting molybdenum layer in a proximitized bilayer structure. The bilayers have a fixed normal metal thickness d<sub>Cu</sub>=1250 &Aring;, on top of a variable superconductor thickness 650 &Aring; &le; d<sub>Mo</sub> &le; 1000 &Aring;. Material characterization techniques including X-ray Diffraction (XRD), Rutherford Backscattering Spectroscopy (RBS), Atomic Force Microscopy (AFM), and 4-point electrical characterization are used to …

Contributors
Kopas, Cameron J, Newman, Nathan, Singh, Rakesh, et al.
Created Date
2014

Cubic boron nitride (c-BN) has potential for electronic applications as an electron emitter and serving as a base material for diodes, transistors, etc. However, there has been limited research on c-BN reported, and many of the electronic properties of c-BN and c-BN interfaces have yet to be reported. This dissertation focused on probing thin film c-BN deposited via plasma enhanced chemical vapor deposition (PECVD) with in situ photoelectron spectroscopy (PES). PES measurements were used to characterize the electronic properties of c-BN films and interfaces with vacuum and diamond. First, the interface between c-BN and vacuum were characterized with ultraviolet PES …

Contributors
Shammas, Joseph, Nemanich, Robert J, Ponce, Fernando, et al.
Created Date
2016

This work is an investigation into the information provided by the concurrent use of in situ reflection high energy electron diffraction (RHEED) and reflection electron energy loss spectroscopy (REELS). The two analytical methods were employed during growth of metal, semiconductor and superconductor thin films by molecular beam epitaxy (MBE). Surface sensitivity of the REELS spectrometer was found to be less than 1 nm for 20 KeV electrons incident at a 2 degree angle to an atomically flat film surface, agreeing with the standard electron escape depth data when adjusted incident angle. Film surface topography was found to strongly influence the …

Contributors
Strawbridge, Brett William, Newman, Nathan, Chamberlin, Ralph, et al.
Created Date
2012

Multifunctional oxide thin-films grown on silicon and several oxide substrates have been characterized using High Resolution (Scanning) Transmission Electron Microscopy (HRTEM), Energy-Dispersive X-ray Spectroscopy (EDX), and Electron Energy-Loss Spectroscopy (EELS). Oxide thin films grown on SrTiO3/Si pseudo-substrate showed the presence of amorphised SrTiO3 (STO) at the STO/Si interface. Oxide/oxide interfaces were observed to be atomically clean with very few defects. Al-doped SrTiO3 thin films grown on Si were of high crystalline quality. The Ti/O ratio estimated from EELS line scans revealed that substitution of Ti by Al created associated O vacancies. The strength of the crystal field in STO was …

Contributors
Dhamdhere, Ajit R., SMITH, DAVID J, McCartney, Martha R., et al.
Created Date
2015

The study of high energy particle irradiation effect on Josephson junction tri-layers is relevant to applications in space and radioactive environments. It also allows us to investigate the influence of defects and interfacial intermixing on the junction electrical characteristics. In this work, we studied the influence of 2MeV Helium ion irradiation with doses up to 5.2×1016 ions/cm2 on the tunneling behavior of Nb/Al/AlOx/Nb Josephson junctions. Structural and analytical TEM characterization, combined with SRIM modeling, indicates that over 4nm of intermixing occurred at the interfaces. EDX analysis after irradiation, suggests that the Al and O compositions from the barrier are collectively …

Contributors
Zhang, Tiantian, Newman, Nathan, Rowell, John M, et al.
Created Date
2012

In this research, our goal was to fabricate Josephson junctions that can be stably processed at 300&deg;C or higher. With the purpose of integrating Josephson junction fabrication with the current semiconductor circuit fabrication process, back-end process temperatures (>350 &deg;C) will be a key for producing large scale junction circuits reliably, which requires the junctions to be more thermally stable than current Nb/Al-AlOx/Nb junctions. Based on thermodynamics, Hf was chosen to produce thermally stable Nb/Hf-HfOx/Nb superconductor tunnel Josephson junctions that can be grown or processed at elevated temperatures. Also elevated synthesis temperatures improve the structural and electrical properties of Nb electrode …

Contributors
Huang, Mengchu, Newman, Nathan, Rowell, John M., et al.
Created Date
2013

The mechanism of loss in high performance microwave dielectrics with complex perovskite structure, including Ba(Zn1/3Ta2/3)O3, Ba(Cd1/3Ta2/3)O3, ZrTiO4-ZnNb2O6, Ba(Zn1/3Nb2/3)O3, and BaTi4O9-BaZn2Ti4O11, has been investigated. We studied materials synthesized in our own lab and from commercial vendors. Then the measured loss tangent was correlated to the optical, structural, and electrical properties of the material. To accurately and quantitatively determine the microwave loss and Electron Paramagnetic Resonance (EPR) spectra as a function of temperature and magnetic field, we developed parallel plate resonator (PPR) and dielectric resonator (DR) techniques. Our studies found a marked increase in the loss at low temperatures is found in …

Contributors
Liu, Lingtao, Newman, Nathan, Marzke, Robert, et al.
Created Date
2013

Microwave properties of low-loss commercial dielectric materials are optimized by adding transition-metal dopants or alloying agents (i.e. Ni, Co, Mn) to tune the temperature coefficient of resonant frequency (τf) to zero. This occurs as a result of the temperature dependence of dielectric constant offsetting the thermal expansion. At cryogenic temperatures, the microwave loss in these dielectric materials is dominated by electron paramagnetic resonance (EPR) loss, which results from the spin-excitations of d-shell electron spins in exchange-coupled clusters. We show that the origin of the observed magnetically-induced shifts in the dielectric resonator frequency originates from the same mechanism, as described by …

Contributors
Zhang, Shengke, Newman, Nathan, Alford, Terry L, et al.
Created Date
2016

Soft magnetic alloys play a significant role for magnetic recording applications and highly sensitivity magnetic field sensors. In order to sustain the magnetic areal density growth, development of new synthesis techniques and materials is necessary. In this work, the effect of oxygen incorporation during electrodeposition of CoFe alloys on magnetic properties, magnetoresistance and structural properties has been studied. Understanding the magnetic properties often required knowledge of oxygen distribution and structural properties of the grown films. Transmission electron microscopy (TEM) was a powerful tool in this study to correlate the oxygen-distribution nanostructure to the magnetic properties of deposited films. Off-axis electron …

Contributors
Elhalawaty, Shereen, Carpenter, Ray, Chamberlin, Ralph, et al.
Created Date
2012

The research described in this dissertation has involved the use of transmission electron microcopy (TEM) to characterize the structural properties of II-VI and III-V compound semiconductor heterostructures and superlattices. The microstructure of thick ZnTe epilayers (~2.4 µm) grown by molecular beam epitaxy (MBE) under virtually identical conditions on GaSb, InAs, InP and GaAs (100) substrates were compared using TEM. High-resolution electron micrographs revealed a highly coherent interface for the ZnTe/GaSb sample, and showed extensive areas with well-separated interfacial misfit dislocations for the ZnTe/InAs sample. Lomer edge dislocations and 60o dislocations were commonly observed at the interfaces of the ZnTe/InP and …

Contributors
Ouyang, Lu, Smith, David J, Mccartney, Martha, et al.
Created Date
2012