1. Key Laboratory of Optoelectronic Technology of Jiangsu Province, School of Physics and Technology, Nanjing Normal University, Nanjing 210023, China
2. National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
3. School of Environmental Science, Nanjing Xiaozhuang University, Nanjing 211171, China