2014 年 35 巻 2 号 p. 102-107
Gallium oxide (Ga2O3) has excellent material properties for power device applications represented by the extremely large breakdown field due to a large bandgap of 4.7-4.9 eV. Another important feature in industry is that large single-crystal β-Ga2O3 bulks and wafers can be fabricated with melt-growth methods. We recently succeeded in fabricating Ga2O3 metal-oxide-semiconductor field-effect transistors (MOSFETs) by using newly developed technologies for making single-crystal bulks, growing conductivity-controlled epitaxial films, and fabricating devices. The MOSFETs exhibited excellent device characteristics including an off-state breakdown voltage over 370 V, an extremely low leakage current, and a high on/off drain current ratio of more than ten orders of magnitude. These results indicate that Ga2O3 have comparable or even more potential than Si and typical widegap semiconductors SiC and GaN for power device applications.