1. Department of Physics and State Key Laboratory of Silicon Materials
2. Zhejiang University
3. Hangzhou
4. P. R. China
5. College of Information and Electrical Engineering
6. Zhejiang University City College
7. Zhejiang
8. Department of Physics
9. Abdul Wali Khan University
10. Mardan 23200
11. Pakistan
12. University of Peshawar
13. Peshawar 25120