Solution-Based Chemical Deposition of Wide and Ultra-Wide Bandgap Oxide Semiconductors

Wide and ultra-wide bandgap oxide semiconductors have unique material properties, such as high breakdown voltage and thermal stability, that make them promising candidates for power electronics, sensors, and other high-performance devices. Deposition of such materials in a cost- and energy-efficient manner is crucial for commercialization. In this thesis, we study solution-based deposition of emerging wide and ultra-wide bandgap oxide semiconductors, with a particular emphasis on solution processed quaternary alloys of zinc tin oxide (ZTO) and the development of a mist chemical vapor deposition (mist-CVD) system to deposit gallium oxide (Ga₂O₃). First, we investigate the effect of magnesium alloying on the structural, electrical and optical properties of amorphous ZTO thin films. The optimal Mg concentration is determined to maximize the crystallization temperature and maintain the desired amorphous phase. We fabricate heterostructures using the band-engineered amorphous ZTO thin-films to study the heterointerfaces. Second, we present a homemade mist-CVD tool design to enable us to deposit various oxide thin films in atmospheric pressure. Finally, by using the custom-built mist-CVD system, we deposit Ga₂O₃ thin films and achieve epitaxial growth by adjusting the growth parameters. The structural and optical properties of the grown thin films are characterized.

Chair: Professor Becky (R.L.) Peterson