Hiroshi Kambayashi, Shin-ichi Kamiya, Nariaki Ikeda, Jiang Li, Sadahiro Kato, Sonomi Ishii, Yasumasa Sasaki, Seikoh Yoshida and Mitsuru Masuda
GaN, like SiC and AlN and other wide bandgap semiconductors, has outstanding features such as being able to operate at high breakdown voltages, high frequencies and high temperatures, and it is therefore expected to find wide application in power conversion devices, etc. In this work the authors have investigated a unique Ti/AlSi/Mo electrode as the ohmic electrode of an AlGaN/GaN HFET. This has made it possible to achieve a contact line resistance less than one-third that of Ti/Al. Fabricating an AlGaN/GaN HFET with a gate width of 200mm using this electrode, we have achieved operating currents of 20 A or more at room temperature and 10 A or more in a 500-K environment, and off breakdown voltages in excess of 450 V at 500 K. And by using high-refractive index SiNx as the surface passivation film, it was possible to achieve a reduction in gate leakage current of about two orders of magnitude compared to SiO2.