1. MIIT Key Laboratory for Low Dimensional Quantum Structure and Devices, School of Materials Sciences & Engineering, Beijing Institute of Technology, 100081 Beijing, China
2. MIIT Key Laboratory for Low Dimensional Quantum Structure and Devices, School of Photonics and Optics, Beijing Institute of Technology, 100081 Beijing, China
3. Department of Materials Science, Shenzhen MSU-BIT University, 518172 Shenzhen, China
4. Institute of Applied Physics and Materials Engineering, University of Macau, 999078 Macau, China