1. Green Innovation Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba 305-8501, Japan
2. Japan Science and Technology Agency, Sanbancho Bldg., 5, Sanbancho Chiyoda-ku, Tokyo 102-0075, Japan
3. Research and Development Department, NEC Lighting, Ltd., 3-1 Nichiden, Minakuchi, Koga, 528-8501, Japan
4. Department of Materials Science and Engineering, Meijo University, 1-501 Shiogamaguchi, Nagoya 468-8502, Japan
5. Nanotube Research Center, National Institute of Advanced Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, 305-8565, Japan