1. Institute of Microelectronics Peking University Beijing 100871 China
2. Key Laboratory of Microelectronic Devices and Circuits (MOE) Peking University Beijing 100871 China
3. Advanced Institute of Information Technology Peking University Hangzhou Zhejiang 311215 P. R. China
4. Frontiers science center for nano‐optoelectronics Peking University Beijing 100871 P. R. China