1. Department
of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
2. 2D
Crystal Consortium, Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
3. Department
of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
4. Center
for Materials, Devices, and Integrated Systems, Rensselaer Polytechnic Institute, Troy, New York 12180, United States