1. College of Material Sciences and Engineering Beijing University of Technology Beijing 100124 P. R. China
2. Key Laboratory of Optoelectronics Technology College of Microelectronics Faculty of Information Technology Beijing University of Technology Beijing 100124 P. R. China
3. School of Mechanical and Electrical Engineering Jingdezhen Ceramic University Jingdezhen Jiangxi 333403 P. R. China
4. School of Physics Beihang University Beijing 100191 P. R. China
5. Electronics and Photonics Research Institute National Institute of Advanced Industrial Science and Technology (AIST) Tsukuba 3058565 Japan