1. Department of Materials Science and Engineering Stanford University Stanford CA 94305 USA
2. Department of Electrical Engineering Stanford University Stanford CA 94305 USA
3. DRAM TD Semiconductor R&D Center Samsung Electronics Samsungjeonja‐ro Hwaseong‐si Gyeonggi‐do 18448 South Korea
4. SLAC National Accelerator Laboratory Menlo Park CA 94025 USA