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Dissertation
DOPING AND ALLOYING OF MONOCLINIC β-Ga2O3 GROWN BY CZOCHRALSKI AND VERTICAL GRADIENT FREEZE
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2022
DOI:
https://doi.org/10.7273/000004638
Handle:
https://hdl.handle.net/2376/124869
Abstract
With the future of electronics focusing on reduced packing size and efficient high-power applications, ultrawide bandgap semiconductors such as β-Ga2O3 are at the forefront of modern research. The energy gap of an ultrawide bandgap semiconductor is 2 – 4 eV larger than historically common semiconducting materials. This allows for a variety of unintentionally and intentionally introduced defects and dopants to alter the behavior of the matrix material, which must be understood if any device structure is to be constructed. Once understood, engineering of the material can alter fundamental properties. Therefore, this work seeks to further the understanding of bulk single crystal growth of gallium oxide and its resultant optical, electrical, and structural properties while doped or alloyed with a variety of transition metals and metals. Electrical behavior was modulated through doping from n¬-type conduction (e.g., Zr, Hf) and semiconducting (e.g., unintentionally doped, Cr) to heavily insulating (e.g., Zn, Cu, Ni). A novel optical behavior for semiconductors, photodarkening, was also achieved with Cu- and Ni-doped β-Ga2O3. β-Ga2O3 was also studied with respect to alloying (e.g., Al, Sc), specifically to alter the size of the optical bandgap. Of course, through doping, alloying, growth, and post-growth annealing, defects are generated at the surface or in the bulk of the sample which impact electrical and optical behavior, and these were subsequently studied via Fourier transformed infrared spectroscopy as well as positron annihilation spectroscopy. These studies are contributions to the fast-paced and rapidly developing field of gallium oxide, where future work may build upon and functionalize doped or alloyed β-Ga2O3 single crystals, described within this body of work into devices which are fit for the future age of power electronics and opto-electronics.
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Details
- Title
- DOPING AND ALLOYING OF MONOCLINIC β-Ga2O3 GROWN BY CZOCHRALSKI AND VERTICAL GRADIENT FREEZE
- Creators
- Jani Jesenovec
- Contributors
- John S McCloy (Advisor)Matthew D McCluskey (Committee Member)Gary S Collins (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 287
- Identifiers
- 99900898734901842
- Language
- English
- Resource Type
- Dissertation