1. Department of Physics, Faculty of Science, King Mongkut’s Institute of Technology Ladkrabang, Bangkok, 10520, Thailand
2. Department of Applied Science for Electronics and Materials, Kyushu University, Kasuga, Fukuoka, 816-8580, Japan
3. Diamond Materials Team, Advanced Power Electronics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka, 563-8577, Japan