1. Hunan Key Laboratory of Micro-Nano Energy Materials and Devices, and School of Physics and Optoelectronics, Xiangtan University, Hunan 411105, China
2. School of Physics and BUAA-UOW Joint Research Centre, Beihang University, Beijing 100191, China
3. School of Electronic and Information Engineering, Changshu Institute of Technology, Changshu 215500, Jiangsu, China
4. Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, P. R. China