1. Guangdong Provincial Key Laboratory of Chip and Integration Technology, School of Semiconductor Science and Technology, Faculty of Engineering, South China Normal University, Foshan 528225, P.R. China
2. School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, P. R. China
3. School of Microelectronics, University of Science and Technology of China, Hefei 230029, P. R. China
4. Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstrasse 400, 01328 Dresden, Germany
5. College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China