1. State Key Laboratory
of Silicon Materials, MOE Key Laboratory of Macromolecular Synthesis
and Functionalization, Department of Polymer Science and
Engineering, Zhejiang University, Hangzhou 310027, People’s Republic of China
2. Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
3. Department
of Physics, Chinese University of Hong Kong, New Territories, Hong Kong, People’s Republic of China