1. Department of Nano Bio Information Technology; KU-KIST Graduate School of Converging Science and Technology; Anam-dong 5-ga, Seongbuk-gu Seoul 136-701 Korea
2. Department of Materials Science and Engineering; Korea University; Anam-dong 5-ga, Seongbuk-gu Seoul 136-701 Korea
3. Electronic Materials Center; Korea Institute of Science and Technology; 39-1 Hawolkok-dong, Seongbuk-gu Seoul 137-791 Korea