β‐Gallium Oxide Devices: Progress and Outlook

Beta‐gallium oxide () has a history of research and development for over 70 years; however, it has attracted little attention as a semiconductor material for a long time. The situation has drastically changed in the past decade, and research on its material properties and developments of growth and device technologies has become active worldwide, mainly from expectations for applications to next‐generation power devices. Most of the specific material properties are attributed to its extremely large bandgap energy of 4.5 eV. The other important material feature is that large‐size single‐crystal bulks can be synthesized by melt growth methods. Herein, after introducing the material properties of that are important for electronic devices, the current status of bulk melt growth and epitaxial thin‐film growth technologies is given. State‐of‐the‐art diodes and transistors are also discussed, including future prospects.