1. The Department of Microelectronics, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
2. The School of Materials Science and Engineering, Yancheng Institute of Technology, 211 East Jianjun Road, Yancheng, Jiangsu 224051, China
3. The Department of Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
4. The Department of Science, Nanjing University of Posts and Telecommunications, Nanjing 210023, China