1. State Key Laboratory of Crystal Materials, Shandong University, 27 South Shanda Road, Jinan, Shandong 250100, P. R. China
2. College of Physics and Electronic Information, Dezhou University, Dezhou, Shandong 253023, P. R. China
3. Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, Jiangsu 210023, China
4. Institute of Medical Genetics, School of Medicine, Shandong University, Jinan, Shandong 250012, P. R. China