1. Department of Physics, Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Xiamen University, Xiamen, Fujian 361005, People’s Republic of China
2. Tianming Physics Research Institute, Changtai, Fujian 363900, People’s Republic of China
3. State Key Laboratory for Physical Chemistry of Solid Surfaces, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, People’s Republic of China