1. State Key Laboratory of Crystal Materials Institute of Crystal Materials Shandong University Jinan 250100 P. R. China
2. State Key Laboratory of Silicon Materials and School of Materials Science and Engineering Zhejiang University Hangzhou 310027 P. R. China
3. School of Microelectronics State Key Laboratory of Crystal Materials Shandong University Jinan 250100 P. R. China
4. Suzhou Research Institute Shandong University Suzhou 215123 P. R. China