1. Department of Materials Science and Engineering, University of California Berkeley, Berkeley, California 94720, United States
2. The National Center for Electron Microscopy, Molecular Foundry, Berkeley, California 94720, United States
3. Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720-8099, United States
4. Department of Electrical Engineering and Computer Sciences, University of California Berkeley, Berkeley, California 94720, United States
5. Institute of Micro- and Nanostructure Research, Center for Nanoanalysis and Electron Microscopy, Interdisciplinary Center for Nanostructured Films, Friedrich-Alexander-Universitat Erlangen-Nurnberg, Erlangen 91058, Germany