[1] Korea Inst Sci & Technol, Ctr Elect Mat, Seoul 136791, South Korea
[2] Korea Inst Sci & Technol, Optoelect Mat Ctr, Seoul 136791, South Korea
[3] Korea Inst Sci & Technol, Nano Mat Anal Ctr, Seoul 136791, South Korea
[4] Yonsei Univ, Sch Elect & Elect Engn, Seoul 120749, South Korea