[1] Hanyang Univ, Div Elect & Comp Engn, Adv Semicond Res Ctr, Seoul 133791, South Korea
[2] Korea Adv Inst Sci & Technol, Dept Mat Sci & Engn, Taejon 305701, South Korea
[3] Hanyang Univ, Div Elect & Comp Engn, Seoul 133791, South Korea
[4] Korea Inst Sci & Technol, Thin Film Mat Res Ctr, Seoul 136791, South Korea
[5] Univ Calif San Diego, La Jolla, CA 92093 USA