1. School of Physics, Beijing Institute of Technology, Beijing 100081, China.
2. Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, China.
3. Department of Physics, Renmin University of China, Beijing 100872, China.
4. Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China.
5. International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology, Shenzhen University, Shenzhen 518060, China.