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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- Genre: Doctoral Dissertation
Description
Ge1-ySny alloys represent a new class of photonic materials for integrated optoelectronics on Si. In this work, the electrical and optical properties of Ge1-ySny alloy films grown on Si, with concentrations in the range 0 ≤ y ≤ 0.04, are studied via a variety of methods. The first microelectronic devices from GeSn films were fabricated using newly developed CMOS-compatible protocols, and the devices were characterized with respect to their electrical properties and optical response. The detectors were found to have a detection range that extends into the near-IR, and the detection edge is found to shift to longer wavelengths with increasing Sn content, mainly due to the compositional dependence of the direct band gap E0. With only 2 % Sn, all of the telecommunication bands are covered by a single detector. Room temperature photoluminescence was observed from GeSn films with Sn content up to 4 %. The peak wavelength of the emission was found to shift to lower energies with increasing Sn content, corresponding to the decrease in the direct band gap E0 of the material. An additional peak in the spectrum was assigned to the indirect band gap. The separation between the direct and indirect peaks was found to decrease with increasing Sn concentration, as expected. Electroluminescence was also observed from Ge/Si and Ge0.98Sn0.02 photodiodes under forward bias, and the luminescence spectra were found to match well with the observed photoluminescence spectra. A theoretical expression was developed for the luminescence due to the direct band gap and fit to the data.
ContributorsMathews, Jay (Author) / Menéndez, Jose (Thesis advisor) / Kouvetakis, John (Thesis advisor) / Drucker, Jeffery (Committee member) / Chizmeshya, Andrew (Committee member) / Ponce, Fernando (Committee member) / Arizona State University (Publisher)
Created2011
Description
A systematic approach to composition has been used by a variety of composers to control an assortment of musical elements in their pieces. This paper begins with a brief survey of some of the important systematic approaches that composers have employed in their compositions, devoting particular attention to Pierre Boulez's Structures Ia . The purpose of this survey is to examine several systematic approaches to composition by prominent composers and their philosophy in adopting this type of approach. The next section of the paper introduces my own systematic approach to composition: the Take-Away System. The third provides several musical applications of the system, citing my work, Octulus for two pianos, as an example. The appendix details theorems and observations within the system for further study.
ContributorsHarbin, Doug (Author) / Hackbarth, Glenn (Thesis advisor) / DeMars, James (Committee member) / Etezady, Roshanne, 1973- (Committee member) / Rockmaker, Jody (Committee member) / Rogers, Rodney (Committee member) / Arizona State University (Publisher)
Created2011
Description
ABSTRACT études; written for violin ensemble, which include violin duets, trios, and quartets, are less numerous than solo études.; These works rarely go by the title "étude;," and have not been the focus of much scholarly research. Ensemble études; have much to offer students, teachers and composers, however, because they add an extra dimension to the learning, teaching, and composing processes. This document establishes the value of ensemble études; in pedagogy and explores applications of the repertoire currently available. Rather than focus on violin duets, the most common form of ensemble étude;, it mainly considers works for three and four violins without accompaniment. Concentrating on the pedagogical possibilities of studying études; in a group, this document introduces creative ways that works for violin ensemble can be used as both études; and performance pieces. The first two chapters explore the history and philosophy of the violin étude; and multiple-violin works, the practice of arranging of solo études; for multiple instruments, and the benefits of group learning and cooperative learning that distinguish ensemble étude; study from solo étude; study. The third chapter is an annotated survey of works for three and four violins without accompaniment, and serves as a pedagogical guide to some of the available repertoire. Representing a wide variety of styles, techniques and levels, it illuminates an historical association between violin ensemble works and pedagogy. The fourth chapter presents an original composition by the author, titled Variations on a Scottish Folk Song: étude; for Four Violins, with an explanation of the process and techniques used to create this ensemble étude.; This work is an example of the musical and technical integration essential to étude; study, and demonstrates various compositional traits that promote cooperative learning. Ensemble études; are valuable pedagogical tools that deserve wider exposure. It is my hope that the information and ideas about ensemble études; in this paper and the individual descriptions of the works presented will increase interest in and application of violin trios and quartets at the university level.
ContributorsLundell, Eva Rachel (Contributor) / Swartz, Jonathan (Thesis advisor) / Rockmaker, Jody (Committee member) / Buck, Nancy (Committee member) / Koonce, Frank (Committee member) / Norton, Kay (Committee member) / Arizona State University (Publisher)
Created2011
Description
As existing solar cell technologies come closer to their theoretical efficiency, new concepts that overcome the Shockley-Queisser limit and exceed 50% efficiency need to be explored. New materials systems are often investigated to achieve this, but the use of existing solar cell materials in advanced concept approaches is compelling for multiple theoretical and practical reasons. In order to include advanced concept approaches into existing materials, nanostructures are used as they alter the physical properties of these materials. To explore advanced nanostructured concepts with existing materials such as III-V alloys, silicon and/or silicon/germanium and associated alloys, fundamental aspects of using these materials in advanced concept nanostructured solar cells must be understood. Chief among these is the determination and predication of optimum electronic band structures, including effects such as strain on the band structure, and the material's opto-electronic properties. Nanostructures have a large impact on band structure and electronic properties through quantum confinement. An additional large effect is the change in band structure due to elastic strain caused by lattice mismatch between the barrier and nanostructured (usually self-assembled QDs) materials. To develop a material model for advanced concept solar cells, the band structure is calculated for single as well as vertical array of quantum dots with the realistic effects such as strain, associated with the epitaxial growth of these materials. The results show significant effect of strain in band structure. More importantly, the band diagram of a vertical array of QDs with different spacer layer thickness show significant change in band offsets, especially for heavy and light hole valence bands when the spacer layer thickness is reduced. These results, ultimately, have significance to develop a material model for advance concept solar cells that use the QD nanostructures as absorbing medium. The band structure calculations serve as the basis for multiple other calculations. Chief among these is that the model allows the design of a practical QD advanced concept solar cell, which meets key design criteria such as a negligible valence band offset between the QD/barrier materials and close to optimum band gaps, resulting in the predication of optimum material combinations.
ContributorsDahal, Som Nath (Author) / Honsberg, Christiana (Thesis advisor) / Goodnick, Stephen (Committee member) / Roedel, Ronald (Committee member) / Ponce, Fernando (Committee member) / Arizona State University (Publisher)
Created2011
Description
Raman scattering from Ge-Si core-shell nanowires is investigated theoretically and experimentally. A theoretical model that makes it possible to extract quantitative strain information from the measured Raman spectra is presented for the first time. Geometrical and elastic simplifications are introduced to keep the model analytical, which facilitates comparison with experimental results. In particular, the nanowires are assumed to be cylindrical, and their elastic constants isotropic. The simple analytical model is subsequently validated by performing numerical calculations using realistic nanowire geometries and cubic, anisotropic elastic constants. The comparison confirms that the analytic model is an excellent approximation that greatly facilitates quantitative Raman work, with expected errors in the strain determination that do not exceed 10%. Experimental Raman spectra of a variety of core-shell nanowires are presented, and the strain in the nanowires is assessed using the models described above. It is found that all structures present a significant degree of strain relaxation relative to ideal, fully strained Ge-Si core-shell structures. The analytical models are modified to quantify this strain relaxation.
ContributorsSingh, Rachna (Author) / Menéndez, Jose (Thesis advisor) / Drucker, Jeffery (Committee member) / Ponce, Fernando (Committee member) / Tsen, Kong-Thon (Committee member) / Bennett, Peter (Committee member) / Arizona State University (Publisher)
Created2011
Description
Despite a quickly growing repertoire list for the brass quintet, the music of the early Argentine tango has remained relatively neglected by brass quintet arrangers and performers. With the goal of bringing a neglected art form to the brass quintet repertoire, three arrangements based on early twentieth century Argentine tango songs are presented here: "Elegante Papirusa" by Tito Roccatagliata, "A La Gran Muñeca" by Jesús Ventura, and "La Cotorrita" by Samuel Castriota. The arrangements follow the style of three early recordings produced by The Victor Talking Machine in 1920 and 1922, as performed by two authentic Argentine orquesta típicas: Orquesta Típica Select and Orquesta Típica Fresedo. A brief history of the style and instrumental evolution of tango music from its influences and origins up until 1920 is discussed, followed by a detailed account of the musicians and circumstances involved in the three early recordings. An explanation of the issues encountered by the author in adapting the early tango style to the brass quintet setting is discussed, along with the solutions realized in order to make the project successful and practical for a moderately advanced brass quintet. The full brass quintet scores are provided as part of the Appendix.
ContributorsCamacho, Gustavo (Musician) (Author) / Ericson, John Q (Thesis advisor) / Pilafian, Samuel (Committee member) / Schuring, Martin (Committee member) / Campbell, Andrew (Committee member) / Rockmaker, Jody (Committee member) / Arizona State University (Publisher)
Created2011
Raman spectroscopy characterization of anharmonicity and alloying effects in semiconductor materials
Description
The chemical sensitivity and spatial resolution of Raman spectroscopy, combined with the sensitivity of modern systems that can easily detect single atomic layers, have made this technique a preferred choice for the strain characterization of complex systems such as nanoscale complementary metal-oxide-semiconductor - CMOS - devices. A disadvantage of Raman spectroscopy, however, is that the shifts associated with strain are not related to the geometrical deformations in any obvious way, so that careful calibrations are needed to determine the anharmonic coefficients (p, q and r) that relate strain to Raman shifts. A new set of measurements of the Raman shift in strained Ge films grown on relaxed SiGe buffer layers deposited on Si substrates is presented, and thereby, a new consistent set of values for the parameters p and q for Ge has been proposed. In this dissertation the study of the vibrational properties of Ge1-xSnx alloys has also been reported. The temperature dependence of the Raman spectrum of Ge-rich Ge1-x Snx and Ge1-x-ySi xSny alloys has been determined in the 10 K - 450 K range. The Raman line shift and width changes as a function of temperature are found to be virtually identical to those observed in bulk Ge. This result shows that the anharmonic decay process responsible for the temperature dependence is extremely robust against the alloy perturbation.
ContributorsBagchi, Sampriti (Author) / Menéndez, Jose (Thesis advisor) / Treacy, Michael (Committee member) / Ponce, Fernando (Committee member) / Tsen, Kong-Thon (Committee member) / Rez, Peter (Committee member) / Arizona State University (Publisher)
Created2011
Description
This thesis describes the fabrication of several new classes of Ge1-x-ySixSny materials with the required compositions and crystal quality to engineer the band gaps above and below that of elemental Ge (0.8 eV) in the near IR. The work initially focused on Ge1-x-ySixSny (1-5% Sn, 4-20% Si) materials grown on Ge(100) via gas-source epitaxy of Ge4H10, Si4H10 and SnD4. Both intrinsic and doped layers were produced with defect-free microstructure and viable thickness, allowing the fabrication of high-performance photodetectors. These exhibited low ideality factors, state-of-the-art dark current densities and adjustable absorption edges between 0.87 and 1.03 eV, indicating that the band gaps span a significant range above that of Ge. Next Sn-rich Ge1-x-ySixSny alloys (2-4% Si and 4-10% Sn) were fabricated directly on Si and were found to show significant optical emission using photoluminescence measurements, indicating that the alloys have direct band gaps below that of pure Ge in the range of 0.7-0.55 eV. A series of Sn-rich Ge1-x-ySixSny analogues (y>x) with fixed 3-4% Si content and progressively increasing Sn content in the 4-10% range were then grown on Ge buffered Si platforms for the purpose of improving the material's crystal quality. The films in this case exhibited lower defect densities than those grown on Si, allowing a meaningful study of both the direct and indirect gaps. The results show that the separation of the direct and indirect edges can be made smaller than in Ge even for non-negligible 3-4% Si content, confirming that with a suitable choice of Sn compositions the ternary Ge1-x-ySixSny reproduces all features of the electronic structure of binary Ge1-ySny, including the sought-after indirect-to-direct gap cross over. The above synthesis of optical quality Ge1-x-ySixSny on virtual Ge was made possible by the development of high quality Ge-on-Si buffers via chemical vapor deposition of Ge4H10. The resultant films exhibited structural and electrical properties significantly improved relative to state-of-the-art results obtained using conventional approaches. It was found that pure Ge4H10 facilitates the control of residual doping and enables p-i-n devices whose dark currents are not entirely determined by defects and whose zero-bias collection efficiencies are higher than those obtained from samples fabricated using alternative Ge-on-Si approaches.
ContributorsXu, Chi (Author) / Kouvetakis, John (Thesis advisor) / Menéndez, Jose (Thesis advisor) / Chizmeshya, Andrew (Committee member) / Drucker, Jeffrey (Committee member) / Ponce, Fernando (Committee member) / Arizona State University (Publisher)
Created2013
Description
This thesis presents a new arrangement of Richard Peaslee's trombone solo "Arrows of Time" for brass band. This arrangement adapts Peaslee's orchestration - and subsequent arrangement by Dr. Joshua Hauser for wind ensemble - for the modern brass band instrumentation and includes a full score. A brief biography of Richard Peaslee and his work accompanies this new arrangement, along with commentary on the orchestration of "Arrows of Time", and discussion of the evolution and adaptation of the work for wind ensemble by Dr. Hauser. The methodology used to adapt these versions for the brass band completes the background information.
ContributorsMalloy, Jason Patrick (Author) / Ericson, John (Thesis advisor) / Oldani, Robert (Committee member) / Rockmaker, Jody (Committee member) / Arizona State University (Publisher)
Created2013
Description
Bright Summer, a one-movement piece for orchestra, was composed in Arizona, and completed in February 2013. The piece is approximately twelve minutes long. The motivation for writing this piece was the death of my mother the year before, in 2012. The prevailing mood of this work is bright and pleasant, expressing my mother's cheerful personality when she was alive. It also portrays bright summer days which resemble my mother's spirit. Thus, soundscape plays an important role in this work. It depicts summer breeze, rustling sounds of leaves, and, to translate a Korean saying, "high blue skies." This soundscape opens the piece as well as closes it. In the middle section, the fast upbeat themes represent my mother's witty and optimistic personality. The piece also contains the presence of a hymn tune, The Love of God is Greater Far, which informs the motivic content and also functions as the climax of the piece. It was my mother's favorite hymn and we used to sing it together following her conversion to Christianity. The piece contains three main sections, which are held together by transitional material based on the soundscape and metric modulations. Unlike my earlier works, Bright Summer is tonal, with upper tertian harmonies prevailing throughout the piece. However, the opening and closing soundscapes do not have functional harmonies. For example, tertian chords appear and vanish silently, leaving behind some resonant sounds without any harmonic progression. Overall, the whole piece is reminiscent of my mother who lived a beautiful life.
ContributorsKim, JeeYeon (Composer) / DeMars, James (Thesis advisor) / Hackbarth, Glenn (Committee member) / Rogers, Rodney (Committee member) / Levy, Benjamin (Committee member) / Rockmaker, Jody (Committee member) / Arizona State University (Publisher)
Created2013