1. State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
2. Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
3. Yangtze Delta Institute of Optoelectronics, Peking University, Nantong, Jiangsu 226010 China
4. Institute of Physics, Chinese Academy of Sciences, Beijing, 100190 China
5. Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, China
6. Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen 9746AG, The Netherlands