1. Graduate School of Engineering; Hokkaido University; Kita 13, Nishi 8, Kita-ku Sapporo Hokkaido 060-8628 Japan
2. Power Electronics Reliability Laboratory; Green Electronics Research Institute, Kitakyushu; 1-8 Hibikino, Wakamatsu-ku Kitakyushu Fukuoka 808-0135 Japan
3. Department of Engineering Physics, Electronics and Mechanics; Nagoya Institute of Technology; Gokiso-cho, Showa-ku Nagoya Aichi 466-8555 Japan
4. Institute of Industrial Science; The University of Tokyo; 4-6-1 Komaba Meguro-ku Tokyo 153-8505 Japan
5. Nanomaterials Research Institute; National Institute of Advanced Industrial Science and Technology (AIST); Central 5, 1-1-1 Higashi Tsukuba Ibaraki 305-8565 Japan