1. NUS
Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, 28 Medical Drive, Singapore117456, Singapore
2. Department
of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
3. Department
of Physics, Imperial College London, London SW7 2AZ, United Kingdom
4. Institute
of Materials Research and Engineering, Agency for Science, Technology, and Research (A*STAR), 2 Fusionopolis Way, #08-03 Innovis, Singapore 138634, Singapore
5. Department
of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
6. Department
of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore
7. Physical
Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955−6900, Kingdom of Saudi Arabia
8. Centre
for Advanced 2D Materials, National University of Singapore, 2 Science
Drive 3, Singapore 117542, Singapore
9. Chair
in Hybrid Nanosystems, Faculty of Physics, Ludwig-Maximilians-Universität München, Munich 80799, Germany
10. Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372, Singapore