Gallium Oxide Power Electronics: The Key Semiconductor for Realizing Energy Sustainable Future

Gallium oxide (Ga<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>) is a material with a history of research and development spanning approximately 70 years; however, it had attracted little attention as a semiconductor for a long time. This situation has changed dramatically in the past decade, and its research and development in materials and devices has become active worldwide, mainly due to expectations for applications to next-generation power devices. Many of its distinctive physical properties originated from the very large bandgap of 4.5 eV. Another important feature is that it is possible to grow large single-crystal bulks by melt growth. In this article, first, physical properties of β-Ga<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>, bulk melt growth, and thin-film epitaxial growth technologies are discussed. Then, state-of-the-art β-Ga<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> diodes and transistors are introduced.