1. School
of Electrical and Electronics Engineering, Chung-Ang University, Seoul 156-756, Korea
2. UNIST
Central Research Facilities, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Korea
3. Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
4. Department of Physics, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Korea
5. School of Advanced
Materials Science and Engineering, Hanbat University, Daejeon 305-719, Korea
6. School of Advanced Materials
Science and Engineering, Sungkyunkwan University, Suwon, Korea
7. Department
of Chemistry, Chung-Ang University, Seoul, Korea