1. Department of Electrical and Computer EngineeringInter-University Semiconductor Research CenterSeoul National University 1 Gwanak-ro, Gwanak-gu Seoul 08826 Republic of Korea
2. Realistic Media Research CenterInnovative Technology Research DivisionGumi Electronics & Information Technology Research Institute (GERI) 350-27 Gumidaero Gumi 39253 Republic of Korea
3. Department of Energy ScienceCenter for Artificial AtomsSungkyunkwan University (SKKU) Suwon-Si Gyeonggi-do 16419 Republic of Korea
4. Department of Electrical EngineeringPusan National University 2, Busandaehak-ro 63beon-gil, Geumjeong-gu Busan 46241 Republic of Korea