1. Sensing System Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 807-1 Shuku-machi, Tosu, Saga 841-0052, Japan
2. Department of Applied Science for Electronics and Materials, Kyushu University, Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
3. Diamond Materials Team, Advanced Power Electronics Research Center, National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan
4. Device Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564, Japan