1. Japan Science and Technology Corporation, c/o NEC Corporation, 34 Miyukigaoka, Tsukuba 305-8501, Japan
2. Department of Material Science and Engineering, Faculty of Science and Technology, Meijo University, 1501 Shiogamaguchi, Tenpaku, Nagoya 468-8502, Japan
3. Physical Chemistry, Materials Science, Graduate School of Natural Science and Technology, and Center for Frontier Electronics and Photonics, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan