1. School of Physics and Optoelectronic Engineering, Yangtze University, Jingzhou 434023, P. R. China
2. College of Physics, Guizhou Province Key Laboratory for Photoelectrics Technology and Application, Guizhou University, Guiyang 550025, P. R. China
3. Key Laboratory of Materials Physics of Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Daxue Road 75, Zhengzhou, 450052, P. R. China
4. Wuhan National Laboratory for Optoelectronics, School of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, P. R. China