1. Department of Materials Science and Engineering, Korea University, 145, Anam-ro Seongbuk-gu, Seoul 02841, Republic of Korea
2. Center for Neuromorphic Engineering, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil Seongbuk-gu Seoul 02792, Republic of Korea
3. Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California 92093-0407, United States
4. School of Electrical Engineering, Korea University, Seoul 02841, Republic of Korea
5. Division of Materials Science and Engineering, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul 15588, Republic of Korea
6. Department of Nuclear Engineering, Hanyang University, 222 Wangsimni-ro Seongdong-gu, Seoul 04763, Republic of Korea
7. Samsung Electronics Co. Ltd., Yongin-si, Gyeonggi-do 11677, Republic of Korea