1. School of Information and Communication Engineering, Sungkyunkwan University (SKKU), 2066 Seobu-ro, Jangan-gu, Suwon City 440-746, Korea
2. Semiconductor R&D Center, Samsung Electronics, 1, Samsungjeonja-ro, Hwaseong-City, Gyeonggi-Do 18448, South Korea
3. Advanced Institute of Nano-Technology (SAINT), Sungkyunkwan University (SKKU), 2066, Seobu-ro, Jangan-gu, Suwon City 440-746, Korea