1. Electrical and Electronic Engineering and Information Systems; The University of Tokyo; 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan
2. Department of Materials Science and Engineering; The University of Texas at Dallas; 800 W. Campbell Rd. Richardson Texas 75080-3021 USA
3. Exploratory Research for Advanced Technology (ERATO); Japan Science and Technology Agency (JST); 2-11-16, Yayoi Bunkyo-ku Tokyo 113-0032 Japan