1. Department of Materials Science and Engineering, The Pennsylvania State University, University Park ,Pennsylvania 16802, United States
2. Center for Nanoscale Science, The Pennsylvania State University, University Park ,Pennsylvania 16802, United States
3. Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
4. 2-Dimensional Crystal Consortium, The Pennsylvania State University, University Park ,Pennsylvania 16802, United States
5. Department of Materials Science and Engineering, The University of Texas at Dallas, Dallas ,Texas 75080, United States
6. Laboratory for Physical Sciences, College Park, College Park ,Maryland 20740, United States
7. Department of Materials Science and Engineering, McMaster University, Hamilton ,Ontario L8S 4L8, Canada
8. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
9. Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park ,Pennsylvania 16802, United States
10. Materials Research Institute, The Pennsylvania State University, University Park ,Pennsylvania 16802, United States
11. Canadian Centre for Electron Microscopy, McMaster University, Hamilton ,Ontario L8S 4M1, Canada