1. Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Kobe, Hyogo 657-8501, Japan
2. Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan
3. Division of Chemistry, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan