1. Department of Materials Science and Engineering with Inter-University Semiconductor Research Center (ISRC), Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
2. Department of Electrical Engineering, Stanford University, Stanford, California 94305-2311
3. Department of Electronic Engineering and New Technology Component & Material Research Center (NCMRC), Gachon University, Seongnam-si, Gyeonggi-do 13120, Republic of Korea