1. School of Physics and Technology, Center for Nanoscience and Nanotechnology, and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072, China
2. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
3. Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
4. School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
5. School of Microelectronics, Wuhan University, Wuhan 430072, China
6. Songshan Lake Materials Laboratory, Dongguan 523808, China