1. Department of Electrical and Computer Engineering, University of Connecticut, Storrs, Connecticut 06269, USA
2. Gatan Inc., 5794 W. Las Positas Blvd., Pleasanton, California 94588, USA
3. Department of Materials Characterization, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
4. Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
5. The National Graphene Institute, University of Manchester, Manchester M13 9PL, United Kingdom
6. Department of Chemical and Biomolecular Engineering, University of Connecticut, Storrs, Connecticut 06269, USA
7. Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA