1. Center for Electronic Materials and Devices Korea Institute of Science and Technology (KIST) Hwarangno 14-gil 5 Seongbuk-gu Seoul 02792 Korea
2. School of Electrical and Electronic Engineering Yonsei University 50 Yonsei-ro Seodaemun-gu Seoul 03722 Korea
3. School of Electrical Engineering Korea Advanced Institute of Science and Technology (KAIST) 291, Daehak-ro Yuseong-gu Daejeon 34141 Korea
4. Division of Nano and Information Technology KIST School at University of Science and Technology Hwarangno 14-gil 5 Seongbuk-gu Seoul 02792 Korea