1. Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 138634, Singapore
2. Centre for BioImaging Sciences and Department of Biological Sciences, National University of Singapore, 117557, Singapore
3. Department of Physics, National University of Singapore, 117551, Singapore
4. imec, Kapeldreef 75, B-3001, Leuven, Belgium
5. Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois60607, United States
6. Department of Materials Science and Engineering, National University of Singapore, 117575, Singapore
7. Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 117546, Singapore
8. Departments of Physics, Pharmaceutical Sciences, and Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois60607, United States