1. Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan
2. Nano-science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei 11529, Taiwan
3. Department of Physics, National Taiwan University, Taipei 10617, Taiwan
4. Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
5. Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
6. Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
7. Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
8. Advanced Research Centre for Green Materials Science and Technology, National Taiwan University, Taipei 10617, Taiwan