1. Center for Nanochemistry (CNC); Beijing Science and Engineering Center for Nanocarbons; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 China
2. State Key Laboratory of Solid-State Lighting; Institute of Semiconductors; Chinese Academy of Sciences; Beijing 100083 China
3. Beijing Engineering Research Center for the 3rd Generation Semiconductor Materials and Application; Beijing 100083 China
4. School of Microelectronics; University of Chinese Academy of Sciences; Beijing 101408 China
5. Electron Microscopy Laboratory; and International Center for Quantum Materials; School of Physics; Peking University; Beijing 100871 China
6. Key Laboratory for Micro-/Nano-Optoelectronic Devices of Ministry of Education; School of Physics and Electronics; Hunan University; Changsha 410082 China
7. State Key Laboratory of Superlattices and Microstructures; Institute of Semiconductors; Chinese Academy of Sciences; Beijing 100083 China
8. Beijing Graphene Institute (BGI); Beijing 100095 P. R. China
9. Collaborative Innovation Centre of Quantum Matter; Beijing 100871 China