1. Institute of Physics and Applied Physics; Yonsei University; Seoul 120-749 Korea
2. Department of Material Science and Engineering; Yonsei University; Seoul 120-749 Korea
3. Process Development Team; Semiconductor R&D Center, Samsung Electronics Co., Ltd.; Yongin 446-711 Korea
4. Korea Research Institute of Standards and Science; Daejeon 305-540 Korea
5. Division of Material Science; Korea Basic Science Institute; Daejeon 305-540 Korea