1. Center of General Studies, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan
2. Department of Physics, University of Houston, Houston, 77204 TX, USA
3. Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
4. Hierarchical Green-Energy Materials (Hi-GEM) Research Center, National Cheng Kung University, Tainan 70101, Taiwan