Affiliation: | a School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea b Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440-746, Republic of Korea c School of Advanced Materials and System Engineering, Kumoh National Institute of Technology, Yangho-dong, Gumi, Gyeongbuk 730-701, Republic of Korea |