1. School of Semiconductor
and Chemical Engineering, Semiconductor Physics Research Center, Chonbuk National University, Jeonju 561-756, Korea
2. Department of Mechanical Engineering, University of Houston, Houston, Texas 77204-4006, United States
3. Materials
Science and Engineering Program and Texas Center for Superconductivity
at UH (TcSUH), University of Houston, Houston, Texas 77204, United States
4. School of Chemical Engineering, Yeungnam University, Gyeongsan 712-749, South Korea
5. Korea Advanced Nano Fab Center, Suwon 443-700, Republic of Korea