 Gallium oxide GA-203 is a promising material for high-power electronic devices and solar-blind UV photo detectors due to its ultra-large band gap, high breakdown field, and thermal stability. However, challenges remain in P-type doping, defect slash impurities, device process, and contact, dielectrics, and surface passivation. This article provides a timely review on the fundamental understanding of GA-203's electronic band structures, optical properties, and chemistry of de-fax and impurity doping. Recent progress is discussed on epitaxial thin foam growth, chemical and physical properties of de-fax and impurities, P-type doping, and ternary alloys within 203 and 802.03. This article was authored by Jaya Zhang, Julie Sher, Dong Chen Qi, and others.