1. Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113
2. Department of Pure and Applied Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153
3. Institute for Solid State Physics, The University of Tokyo, 7-22-1 Roppongi, Minato-ku, Tokyo 113
4. Electronics Research Laboratory, Kobe Steel, 1-5-5 Takatsukadai, Nishi-ku, Kobe 651-22
5. Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113