1. Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
2. School of Electronics and Information and School of Microelectronics, Northwestern Polytechnical University, 127 West Youyi Road, Xi’an, Shaanxi 710072, China
3. Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
4. Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
5. College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
6. Department of SciTec, University of Applied Sciences Jena, Carl-Zeiss-Promenade 2, 07743 Jena, Germany
7. Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
8. State Key Lab of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China