1. Flexible Information Device Research Section, Electronics and Telecommunications Research Institute, Daejeon 305-700, Republic of Korea
2. Photonics/Wireless Convergence Platform Research Section, Electronics and Telecommunications Research Institute, Daejeon 305-700, Republic of Korea
3. Reality Display Device Research Section, Electronics and Telecommunications Research Institute, Daejeon 305-700, Republic of Korea
4. Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University, Suwon, 440-746, Republic Korea