1. State Key Laboratory for Superlattices and Microstructures
2. Institute of Semiconductors
3. University of Chinese Academy of Sciences
4. Chinese Academy of Sciences
5. Beijing 100083
6. Department of Physics
7. Henan Normal University
8. Xinxiang 453007
9. China
10. School of Electronics and Information Engineering
11. Hebei University of Technology
12. Tianjin 300401