1. School of Physics and Information Technology, Shaanxi Normal University, Xi’an, Shaanxi 710119, People’s Republic of China
2. Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, People’s Republic of China
3. Research Center for Carbon-Based Electronics and Key Laboratory for the Physics and Chemistry of Nanodevices, School of Electronics, Peking University, Beijing 100871, People’s Republic of China
4. Department of Materials Science and Engineering, Macau University of Science and Technology, Taipa, Macau 999078, People’s Republic of China