1. Department of Physics Education, Chonnam National University, Gwangju 61186, Republic of Korea
2. Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080, USA
3. Department of Chemistry, Hanyang University, Seoul 04763, Republic of Korea
4. Department of Electrical Engineering, Center for Semiconductor Technology Convergence, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
5. Department of Materials Science and Engineering, Hanyang University, Seoul 04763, Republic of Korea