1. Department
of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
2. Institute of Materials Research & Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, Singapore 138634, Singapore
3. Centre
for Advanced 2D Materials, National University of Singapore, Block S14,
Level 6, 6 Science Drive 2, Singapore 117546, Singapore
4. Department
of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
5. Sandia National Laboratories, Livermore, California 94551, United States
6. SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen 518060, China
7. Department
of Electrophysics, National Chiao Tung University, Hsinchu 300, Taiwan
8. Physical
Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
9. Institute
of High Performance Computing, Agency for Science Technology and Research, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore