1. Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology
2. Department of Electronics
3. College of Electronic Information and Optical Engineering
4. Nankai University
5. Tianjin 300350
6. Key Laboratory of Nanosystem and Hierarchical Fabrication
7. National Center for Nanoscience and Technology
8. Beijing
9. P. R. China
10. School of Physics and Engineering
11. Key Laboratory of Materials Physics
12. Ministry of Education
13. Zhengzhou University
14. Zhengzhou 450001