1 Nanjing University, National Laboratory of Solid State Microstructures, Nanjing, China
2 Nanjing University, School of Physics, Nanjing, China
3 Nanjing University, Collaborative Innovation Center of Advanced Microstructures, Nanjing, China
4 Qingdao University of Technology, School of Science, Qingdao, China
5 Nanjing University, School of Electronic Science and Engineering, Nanjing, China
6 Hefei National Laboratory, Hefei, China