1. Department of Materials Science and Engineering
2. Kitami Institute of Technology
3. Kitami 090-8507
4. Japan
5. Nanoscience and Nanotechnology Research Center
6. Osaka Prefecture University
7. Osaka 599-8570
8. Laboratory of Nano-Structure Physics
9. Research Institute for Electronic Science
10. Hokkaido University
11. Sapporo 001-0021