1. National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering and Collaborative Innovation Center of Advanced Microstructures; Nanjing University; Nanjing 210093 P. R. China
2. National Laboratory of Solid State Microstructures; School of Physics; Nanjing University; Nanjing 210093 P. R. China
3. Institute of High Performance Computing; 1 Fusionopolis Way 138632 Singapore
4. Department of Physics; Southeast University; Nanjing 211189 China
5. Science and Technology on Monolithic Integrated Circuits and Modules Laboratory; Nanjing Electronic Device Institute; Nanjing 210017 China