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. Institute of High Performance Computing; 1 Fusionopolis Way Singapore 138632 Singapore
3. National Laboratory of Solid State Microstructures; School of Physics; Nanjing University; Nanjing 210093 P. R. China
4. Science and Technology on Monolithic Integrated Circuits and Modules Laboratory; Nanjing Electronic Device Institute; Nanjing 210016 P. R. China