ASU Electronic Theses and Dissertations
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ABSTRACT This thesis focuses on structural characterizations and optical properties of Si, Ge based semiconductor alloys. Two material systems are characterized: Si-based III-V/IV alloys, which represent a possible pathway to augment the optical performance of elemental silicon as a solar cell absorber layer, and Ge-based Ge1-ySny and Ge1-x-ySixSny systems which are applicable to long wavelength optoelectronics. Electron microscopy is the primary tool used to study structural properties. Electron Energy Loss spectroscopy (EELS), Ellipsometry, Photoluminescence and Raman Spectroscopy are combined to investigate electronic band structures and bonding properties. The experiments are closely coupled with structural and property modeling and theory. A …
- Jiang, Liying, Menendez, Jose, Kouvetakis, John, et al.
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Group-IV semiconductor alloys are of interest for Si-integrated optoelectronic applications due to the band gap tunability and enhanced optical capabilities that can be achieved through compositional tuning. This work advances the field by presenting a systematic study of the optical and electronic properties of Ge1-ySny and analogous Ge1-x-ySixSny alloys. The fundamental direct and indirect band gaps of Ge1-ySny materials are measured by room temperature photoluminescence in samples containing 0 ≤ y ≤ 0.11 and a transition to direct gap materials is found to occur at yc = 0.087. This result is enabled by the development of sample growth and processing …
- Gallagher, James Dennis, Menendez, Jose, Kouvetakis, John, et al.
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