1. Hunan Key Laboratory for Super Microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha, Hunan 410083, People’s Republic of China
2. Hunan Key Laboratory of Nanophotonics and Devices, School of Physics and Electronics, Central South University, Changsha, Hunan 410083, People’s Republic of China
3. Low-dimensional Quantum Structures and Quantum Control of Ministry of Education, Department of Physics, Hunan Normal University, Changsha, Hunan 410081, People’s Republic of China
4. Department of Materials Science and Engineering City University of Hong Kong Kowloon, Hong Kong SAR 999077, People’s Republic of China
5. School of Electronic Science & Engineering, and Collaborative Innovation Centre of Advanced Microstructures, Nanjing University, Nanjing, Jiangsu 210008, People’s Republic of China