1. Department of Physics, National Taiwan University, Taipei, 106, Taiwan
2. Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
3. Nano-Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei, 115, Taiwan
4. Department of Materials Science and Engineering, National United University, Miaoli, 360, Taiwan
5. Advanced Research Centre for Green Materials Science and Technology, National Taiwan University, Taipei, 106, Taiwan