1. Institute of NanotechnologyKarlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Germany
2. International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of EducationInstitute of Microscale OptoelectronicsShenzhen University Shenzhen 518060 P.R. China
3. Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of EducationCollege of ChemistryXiangtan University 411105 Xiangtan P.R. China
4. Helmholtz Institute Ulm (HIU) Helmholtzstr. 11 89081 Ulm Germany
5. Karlsruhe Nano Micro FacilityKarlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Germany
6. Institut de Physique et Chimie des Matériaux (IPCMS)Université de Strasbourg BP 43 67034 Strasbourg France