1. Department of Applied Science for Electronics and Materials, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
2. Department of Molecular and Material Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
3. Department of Control and Information Systems Engineering, National Institute of Technology, Kurume College, Kurume, Fukuoka 830-8555, Japan
4. The Electron Microscopy Center, Technology Center for Research and Education Activities, Tohoku University, Sendai 980-8577, Japan