What Is In Store for Gallium Oxide Power Devices in the Next Decade?

Ultrawide-bandgap semiconductors have attracted increasing interests to expand the application space for next-generation power electronics. These research efforts have been driven in large part by a need for new medium/high-voltage power devices that meet stringent requirements for system size and cost in emerging areas such as electrified transportation, motor-drive systems, and renewable energy integration with the grid. Materials with shallow hydrogenic dopants show the best projected performance for power switching. Realizing high material purity with low background compensation will enable low doping concentrations to fully exploit the intrinsic material properties. Due to the availability of shallow donors and low background impurity compensation enabling rapid device prototyping, beta-phase gallium oxide (<i>β</i>-Ga₂O₃) has emerged as a relevant contender for power devices and has repeatedly pushed the boundaries of high-field performance. In addition, <i>β</i>-Ga₂O₃ is the only (ultra)wide-bandgap material that has a melt-grown native substrate, indicating a path to a commercially viable and cost-competitive technology.<br/><br/>As one of the most widely studied ultrawide-bandgap semiconductors today, <i>β</i>-Ga₂O₃ has attracted international attention across disciplines. Thanks to the success of high-purity homoepitaxial growths on bulk substrates, a broad portfolio of <i>β</i>-Ga₂O₃ devices has demonstrated favorable attributes to be the next frontier technology in power conversion, integrated high-voltage RF, and high-temperature electronics. Various strategies of field management, including edge termination techniques and multi-dimensional device architectures, have been devised to effectively harness the high critical electric field afforded by <i>β</i>-Ga₂O₃. Heterojunctions with <i>β</i>-(Al<i>_x</i>Ga_1–<i>x</i>)₂O₃ and <i>p</i>-type oxides (notably NiO) have created an abundance of new design possibilities. Additionally, reports of high-performance packaging, device robustness, and converter applications all consolidate the promise of <i>β</i>-Ga₂O₃ for power electronics. While <i>β</i>-Ga₂O₃ devices are noted for their high-temperature resilience, heat dissipation to limit the junction temperature and improve the component reliability will be critical for maximizing their performance and long-term reliability.<br/><br/>After the first report of a single-crystal <i>β</i>-Ga₂O₃ power device by Higashiwaki and co-workers in 2012, <i>β</i>-Ga₂O₃ has showcased technical and programmatic momentum not seen in decades since the rise of SiC and GaN research. Following a survey of the landmarks in <i>β</i>-Ga₂O₃ research including device engineering, process innovations, and theoretical understandings of relevant physics, I will reflect on the demonstrated benefits as well as unrealized potentials of the emerging <i>β</i>-Ga₂O₃ technology, then conclude with my projections of the future directions and opportunities for <i>β</i>-Ga₂O₃ in the coming decade.