1. Sensors
and Electron Devices Directorate, U.S. Army Research Laboratory, Adelphi, Maryland 20783, United States
2. Material
Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
3. Department of Materials Science and Engineering & Center for Two-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802, United States