*
Corresponding authors
a
SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon, Korea
b
Samsung-SKKU Graphene Center (SSGC), Sungkyunkwan University, Suwon, Korea
c
Department of Energy Science, Sungkyunkwan University, Suwon, Korea
d
School of Advanced Materials, Sungkyunkwan University, Suwon, Korea
e
Department of Nano-mechanics, Korea Institute of Machinery and Materials, Daejeon, Korea
f
AE center, Samsung Advanced Institute of Technology, Korea
g
Graphene center, Samsung Advanced Institute of Technology, Korea
h
Department of Physics and BK21Physics Division, Sungkyunkwan University, Suwon, Korea
i
School of Mechanical Engineering, Sungkyunkwan University, Suwon, Korea
E-mail:
sbaik@me.skku.ac.kr
Fax: +82-31-290-5889
Tel: +82-31-290-7456