1. School of Electrical
Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
2. Department
of Memory Business, Samsung Electronics, San #16 Banwol-Dong, Hwasung-City, Gyeonggi-Do 445-701, Republic of Korea
3. Department
of Nano-process, National Nanofab Center (NNFC), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea