1. SZU‐NUS Collaborative Innovation Center for Optoelectronic Science and TechnologyInternational Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of EducationCollege of Optoelectronic EngineeringShenzhen University Shenzhen 518060 P. R. China
2. Department of PhysicsNational University of Singapore 2 Science Drive 3 Singapore 117551 Singapore
3. Department of Materials Science and EngineeringNational University of Singapore Singapore 117574 Singapore
4. Department of Electrical and Computer EngineeringNational University of Singapore 117583 Singapore
5. Centre for Advanced 2D MaterialsNational University of Singapore Block S14, 6 Science Drive 2 Singapore 117546 Singapore