1. Ningbo Institute of Material Technology and Engineering; Chinese Academy of Sciences; Ningbo 315201 China
2. College of Materials and Science and Opti-Electronic Technology; University of Chinese Academy of Sciences; Beijing City 100049 P. R. China
3. Department of physics; Nanchang University; Nanchang 330031 China
4. Institute of Microstructure and Property of Advanced Materials; Beijing University of Technology; Beijing 100124 China
5. Wuhan National Laboratory for Optoelectronics (WNLO); Huazhong University of Science and Technology (HUST); Wuhan 430074 China