1. Department of Applied Physics and Institution of Energy and Microstructure
2. Nanjing University of Science and Technology
3. Nanjing 210094
4. China
5. State Key Laboratory for Artificial Microstructure & Mesoscopic Physics
6. School of Physics
7. Peking University
8. Beijing 100871
9. National Engineering Research Center of Electromagnetic Radiation Control Materials and State Key Laboratory of Electronic Thin Films and Integrated Devices
10. School of Microelectronics and Solid State Electronics
11. University of Electronic Science and Technology of China
12. Chengdu 610054