1. School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
2. Samsung Electronics, Hwaseong-si, Gyeonggido 18448, Republic of Korea
3. Department of Physics and Research Institute of Basic Sciences, Kyung Hee University, Seoul 02447, Republic of Korea
4. Department of Information Display, Kyung Hee University, Seoul 02447, Republic of Korea
5. Department of Semiconductor & Department of Chemical Engineering (BK21 FOUR Graduate Program), Dong-A University, Busan 49315, Republic of Korea