1. Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
2. Graduate Group in Applied Science and Technology, University of California at Berkeley, Berkeley, California 94720, United States
3. Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley 94720, California United States
4. Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, United States
5. School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287, United States
6. Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
7. International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
8. Kavli Energy NanoSciences Institute at University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States