1. School of Optical and Electronic Information, Key Lab of Functional Materials for Electronic Information (B) of MOE Huazhong University of Science and Technology Wuhan 430074 P. R. China
2. Hubei Key Laboratory of Ferro-Piezoelectric Materials and Devices Hubei University Wuhan 430074 P. R. China
3. Guangxi Key Laboratory of Information Materials Guilin University of Electronic Technology Guilin 541004 P. R. China
4. Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan 430074 P. R. China