1. Department of Physics, National Tsing Hua University, Hsinchu 300044, Taiwan
2. The Affiliated Senior High School of National Taiwan Normal University, Taipei 10658, Taiwan
3. Tsing Hua Interdisciplinary Program, National Tsing Hua University, Hsinchu 300044, Taiwan
4. Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300044, Taiwan
5. Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
6. Department of Physics, National Changhua University of Education, Changhua 50007, Taiwan