1. School of Physics and Information Technology, Shaanxi Normal University, Xi’an 710119, China
2. Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215123, 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, China
4. Department of Materials Science and Engineering, Macau University of Science and Technology, Macau 999078, China