1. School of Electronics Science and Engineering and National Laboratory of Solid State Microstructures, Jiangsu Provincial Key Laboratory of Advanced Photonic and Electrical Materials, Nanjing University, Nanjing 210000, P. R. China
2. State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Institute of Advanced Semiconductors, Hangzhou Innovation Center, Zhejiang University, Hangzhou, Zhejiang 310027, P. R. China
3. School of Information Science and Technology, Nantong University, Nantong 226019, P. R. China