1. School of Physics, Henan Key Laboratory of Photovoltaic Materials, Henan Normal University 1 , Xinxiang, Henan 453007, China
2. School of Semiconductor Science and Technology, South China Normal University 2 , Foshan 528225, People's Republic of China
3. Guangdong Provincial Key Laboratory of Chip and Integration Technology 3 , Guangzhou 510631, People's Republic of China