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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.


Group IV alloy films exhibit the ability to tune both band structure and lattice parameters and have recently attracted attention for their potential applications in Si-photonics and photovoltaics. In this work, several new approaches to produce these alloys directly on Si(100) and Ge(100) wafers are developed. For photovoltaics, use of Ge-buffered Si(100) wafers as a low cost platform for epitaxy of In1-xGaxAs layers was explored. The results indicate that this approach has promise for transitioning from bulk Ge platforms to virtual substrates for a significant cost reduction. The electrical and optical properties of Ge and Ge1-ySny layers produced using several …

Contributors
Beeler, Richard Todd, Kouvetakis, John, Menéndez, José, et al.
Created Date
2012

Metal hydride materials have been intensively studied for hydrogen storage applications. In addition to potential hydrogen economy applications, metal hydrides offer a wide variety of other interesting properties. For example, hydrogen-dominant materials, which are hydrides with the highest hydrogen content for a particular metal/semimetal composition, are predicted to display high-temperature superconductivity. On the other side of the spectrum are hydrides with small amounts of hydrogen (0.1 - 1 at.%) that are investigated as viable magnetic, thermoelectric or semiconducting materials. Research of metal hydride materials is generally important to gain fundamental understanding of metal-hydrogen interactions in materials. Hydrogenation of Zintl phases, …

Contributors
Puhakainen, Kati, Häussermann, Ulrich, Seo, Dong, et al.
Created Date
2013

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 …

Contributors
Xu, Chi, Kouvetakis, John, Menendez, Jose, et al.
Created Date
2013

The thesis studies new methods to fabricate optoelectronic Ge1-ySny/Si(100) alloys and investigate their photoluminescence (PL) properties for possible applications in Si-based photonics including IR lasers. The work initially investigated the origin of the difference between the PL spectrum of bulk Ge, dominated by indirect gap emission, and the PL spectrum of Ge-on-Si films, dominated by direct gap emission. It was found that the difference is due to the supression of self-absorption effects in Ge films, combined with a deviation from quasi-equilibrium conditions in the conduction band of undoped films. The latter is confirmed by a model suggesting that the deviation …

Contributors
Grzybowski, Gordon J., Kouvetakis, John, Chizmeshya, Andrew, et al.
Created Date
2013

Optoelectronic and microelectronic applications of germanium-based materials have received considerable research interest in recent years. A novel method for Ge on Si heteroepitaxy required for such applications was developed via molecular epitaxy of Ge5H12. Next, As(GeH3)3, As(SiH3)3, SbD3, S(GeH3)2 and S(SiH3)2 molecular sources were utilized in degenerate n-type doping of Ge. The epitaxial Ge films produced in this work incorporate donor atoms at concentrations above the thermodynamic equilibrium limits. The donors are nearly fully activated, and led to films with lowest resistivity values thus far reported. Band engineering of Ge was achieved by alloying with Sn. Epitaxy of the alloy …

Contributors
Senaratne, Charutha Lasitha, Kouvetakis, John, Chizmeshya, Andrew, et al.
Created Date
2016

Modern semiconductor technologies have been dominated by group-IV materials and III-V analogues. The development of hybrid derivatives combining appropriate members of these systems has been of interest for the purpose of extending the optoelectronic capabilities of the state-of-the-art. Early work on pseudo-binary (III-V)-IV alloys, described with the general formula (III-V)1-x(IV2)x, showed limited progress due to phase segregation, auto-doping and compositional inhomogeneities. Recently, new techniques were introduced for synthesizing new classes of (III-V)-IV hybrid materials using reactions of V(IVH3)3 molecules [V = N, P, As and IV = Si, Ge] with group-III elements (B, Al, Ga, In). The reactions produce (III-V)-IV3 …

Contributors
Sims, Patrick, Kouvetakis, John, Chizmeshya, Andrew V. G., et al.
Created Date
2017

The work described in this thesis explores the synthesis of new semiconductors in the Si-Ge-Sn system for application in Si-photonics. Direct gap Ge1-ySny (y=0.12-0.16) alloys with enhanced light emission and absorption are pursued. Monocrystalline layers are grown on Si platforms via epitaxy-driven reactions between Sn- and Ge-hydrides using compositionally graded buffer layers that mitigate lattice mismatch between the epilayer and Si platforms. Prototype p-i-n structures are fabricated and are found to exhibit direct gap electroluminescence and tunable absorption edges between 2200 and 2700 nm indicating applications in LEDs and detectors. Additionally, a low pressure technique is described producing pseudomorphic Ge1-ySny …

Contributors
Wallace, Patrick Michael, Kouvetakis, John, Menendez, Jose, et al.
Created Date
2018