1. Department of Physics and Institutes of Nanoscience National Chung Hsing University Taichung 40227 Taiwan
2. Department of Electrical Engineering and Institute of Electronic Engineering National Tsing Hua University Hsinchu 300 Taiwan
3. Department of Physics Center of Atomic Initiative for New Materials National Taiwan University Taipei 10617 Taiwan
4. Department of Electrophysics National Chiao Tung University Hsinchu 300 Taiwan
5. Department of Physics National Cheng Kung University Tainan 70101 Taiwan
6. Research Center for Sustainable Energy and Nanotechnology National Chung Hsing University Taichung 40227 Taiwan
7. Graduate Institute of Biomedical Engineering National Chung Hsing University Taichung 40227 Taiwan
8. Institutes of Nanoscience National Chung Hsing University Taichung 40227 Taiwan