1. School of Electronic and Computer Engineering
2. Peking University
3. Shenzhen Graduate School
4. Shenzhen 518055
5. China
6. Department of Materials Science and Engineering
7. Research Center for Sustainable Energy and Nanotechnology
8. National Chung Hsing University
9. Taichung 40227
10. Taiwan
11. Department of Physics
12. National Sun Yat-sen University
13. Kaohsiung 804
14. Institute of Materials and Optoelectronics