1. Department of Material Science and Engineering, Stanford University, Stanford, California 94305, United States
2. Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
3. National Laboratory of Solid-State Microstructures, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
4. School of Material Science and Engineering, Beihang University, Beijing 100191, China
5. Department of Applied Physics, Stanford University, Stanford, California 94305, United States