1. Faculty of Physics and Electronic Science Hubei University Hubei Key Laboratory of Ferro‐& Piezoelectric Materials and Devices Wuhan 430062 P. R. China
2. School of Electronic and Computer Engineering Peking University Shenzhen Graduate School Shenzhen 518055 P. R. China
3. Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen 518055 P. R. China