1. Emerging Materials Research Section, Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea
2. Department of Advanced Device Engineering, University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
3. School of Electronics and Information Engineering, Korea Aerospace University, Goyang-city, Gyeonggi-do 10540, Republic of Korea