Solid State Epitaxial growth of Bulk and Thin Film Single Crystals
Date
2023-02
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Publisher
New York State College of Ceramics at Alfred University. Inamori School of Engineering.
Abstract
Recent studies have shown that many challenges encountered in conventional single crystal growth methods, including high production costs, can be overcome using the solid-state single-crystal growth (SSCG) approach, which has been recognized as a simple and cost-effective alternative for obtaining single crystals. Thus far, the development of the SSCG technique has enabled the fabrication of single crystals with complex chemical compositions and even incongruent melting behavior through the use of a recently proposed mechanism of grain boundary migration known as the "mixed control mechanism" and the associated principles of microstructural evolution. The first chapter of this thesis presents the study of the mechanisms and kinetics of this novel single crystal growth technique using undoped and Nd-doped yttrium aluminum garnet (YAG and Nd:YAG) optical materials as the model systems. The results of the study have broadened the knowledge of the SSCG by demonstrating the effects of different parameters, including the application of external pressure during processing, doping, temperature, and oxygen partial pressure that can be used to control and predict the quality of single crystals and grain growth behavior during the single crystal conversion process. Further on, the progression of this project led to the study not only on bulk YAG single crystals but also thin (single crystal) YAG and Nd:YAG and aluminum gallium oxide (β-(AlxGa1-x)2O3) epitaxial films with the aim of extending the collection of potential applications of these well-known optical and optoelectronic materials. Good-quality epitaxial films of YAG and Nd:YAG on YAG single crystal substrates (chapter II) and β-(AlxGa1-x)2O3) on sapphire substrates (chapter III) were generated and characterized in terms of their structural, chemical, and optical properties using a less studied sol-gel spin-coating film fabrication approach. The results of the study on the wide-bandgap semiconductor β-(AlxGa1-x)2O3 films on the effects of tuning the bandgap by changing the Al concentration (i.e., bandgap engineering), substrate orientation, and rare-earth doping collectively demonstrating the effectiveness of a simple and inexpensive sol-gel spin-coating deposition technique to fabricate novel materials and compositions with tunable properties for a broad range of next-generation electronic, optoelectronic, and photonic devices.
Description
Thesis completed in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Ceramic Engineering at the Inamori School of Engineering, New York State College of Ceramics at Alfred University
Type
Thesis
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Keywords
Crystal growth, Epitaxy