1. School of Materials Science and Engineering
2. Hebei University of Technology
3. Tianjin 300130
4. P. R. China
5. Hebei Key Laboratory of Boron Nitride Micro and Nano Materials
6. State Key Laboratory of Electronic Thin Film and Integrated Device
7. School of Optoelectronic Information
8. University of Electronic Science and Technology of China
9. Chengdu
10. China