1. Department of Electrical and Computer Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
2. Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, Illinois 60439, United States
3. Department of Materials Science and Engineering, Northwestern University, 2200 Campus Drive, Evanston, Illinois 60208, United States
4. Northwestern University Atomic and Nanoscale Characterization Experimental (NUANCE) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States