1. Institute of NanotechnologyKarlsruhe Institute of Technology (KIT) 76344 Eggenstein-Leopoldshafen Germany
2. International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of EducationCollege of Physics and Optoelectronic EngineeringShenzhen University Shenzhen 518060 China
3. Department of Physics E20Technical University of Munich (TUM) 85748 Garching Germany
4. College of New Materials and New EnergiesShenzhen Technology University Shenzhen 518118 China
5. Department of PhysicsSouthern University of Science and Technology Shenzhen 518055 China
6. IPCMS-CNRSUniversité de Strasbourg Strasbourg F-67034 France