1. Department of Applied Physics
2. Zhejiang University of Technology
3. Hangzhou 310023
4. China
5. National Laboratory of Solid State Microstructures and Department of Physics
6. Nanjing University
7. Nanjing 210093
8. Department of Electrical and Computer Engineering
9. Iowa State University
10. Ames
11. USA
12. College of Electronic Science and Engineering
13. Nanjing University of Posts and Telecommunications
14. Nanjing 210023
15. National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering
16. School of Mathematics and Physics
17. Jiangsu University of Technology
18. Changzhou 213001