1. College of Chemistry, Beijing Normal University, Beijing 100875, PR China
2. Kunming Institute of Physics, Kunming 650223, PR China
3. State Key Laboratory of Radio Frequency Heterogeneous Integration, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, PR China
4. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, PR China
5. School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, PR China
6. School of materials and Energy, State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, PR China
7. Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, PR China
8. College of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Beijing 100049, PR China