1. Dept. of Electrical Engineering, Stanford University, Stanford, California 94305, United States
2. Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
3. Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
4. Chair of Electronic Devices, RWTH Aachen University, Aachen, 52074, Germany
5. Dept. of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
6. Precourt Institute for Energy, Stanford University, Stanford, California 94305, United States