1. Department of Materials Science
and Engineering, Korea Advanced Institute of Science and Technology, 335 Science Road, Daejeon, 305-701,
Republic of Korea
2. Department
of Advanced Materials
Engineering, Kyonggi University, Iui-dong,
Yeongtong-gu, Suwon, Gyeonggi-do, 443-760, Republic of Korea
3. Graphene Research Center, KAIST
Institute for the NanoCentury, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu,
Daejeon 305-701, Republic of Korea