1. National Laboratory of Solid State Microstructures and Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing 210093 China
2. School of Physics Nanjing University Nanjing 210093 China
3. Key Lab of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) and School of Physics Beijing Institute of Technology Beijing 100081 China
4. Department of Materials Science and Engineering Nanjing University Nanjing 210093 China
5. Institute of Physics and Computational Mathematics Beijing 100088 China
6. Jiangsu Provincial Key Laboratory for Nanotechnology Nanjing University Nanjing 210093 China