Over 80% power-added-efficiency GaN high-electron-mobility transistors on free-standing GaN substrates
Yusuke Kumazaki, Toshihiro Ohki, Junji Kotani, Shiro Ozaki, Yoshitaka Niida, Yuichi Minoura, Masato Nishimori, Naoya Okamoto, Masaru Sato, Norikazu Nakamura, Keiji Watanabe
Abstract
Abstract This paper demonstrates highly efficient GaN high-electron-mobility transistors (HEMTs) on GaN substrates with reduced interface contamination. By applying a hydrofluoric acid-based pre-growth treatment to a GaN substrate, the Si impurity concentration at the interface between the GaN substrate and the epitaxial layer can successfully be reduced. RF performance was enhanced by pre-growth treatment owing to the suppression of Si-induced parasitic loss. As a result, GaN HEMTs on GaN substrates exhibited an excellent power-added efficiency of 82.8% at a 2.45 GHz. To the best of our knowledge, this exceeds that of the previously reported discrete GaN HEMTs at around this frequency range.