A Review of Recent Progress in β-Ga₂O₃ Epitaxial Growth: Effect of Substrate Orientation and Precursors in Metal–Organic Chemical Vapor Deposition

Gallium oxide (Ga₂O₃) is a highly promising ultrawide-bandgap semiconductor for power electronics that emerged about a decade ago. Epitaxial growth Ga₂O₃ at the small scale is demonstrated. In order to develop scalable manufacturing of high-performance epitaxial structures, in-depth understanding of the fundamental growth processes, control parameters, and mechanism is imperative. This review discusses the recent progress in epitaxial growth of β-Ga₂O₃ films and highlights challenges in obtaining high growth rate, low defects, and high carrier mobilities. Compared with the other epitaxy methods, metal–organic chemical vapor deposition (MOCVD) offers a wider growth window and precursor selection option, to minimize the tradeoff between crystal quality and growth rate. Growth rate is inversely proportional to temperature, within a certain temperature window, because of the unavoidable premature gas-phase reactions and desorption of the highly volatile gallium suboxide (Ga₂O) at elevated temperatures. Growth defects, background impurity incorporation, and carrier mobilities can be affected by the choice of MOCVD precursors, nucleation, and adsorption/desorption/diffusion of adatoms on substrate surfaces of different orientations, including the effect of growing on cleavage and noncleavage planes. This review summarizes the current status of the epitaxial growth of β-Ga₂O₃ and analyzes the major factors that enhance mobility and reduce background doping concentration. The insights gained help advance the manufacturability of device-grade epitaxial thin films.