1. Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States
2. Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
3. SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
4. Electron Microscopy Core Facility and Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, Missouri 65211, United States
5. Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211, United States