1. State Key Laboratory of Silicon MaterialsKey Laboratory of Novel Materials for Information Technology of Zhejiang Province and School of Materials Science and EngineeringZhejiang University Hangzhou 310027 P. R. China
2. State Key Laboratory of Advanced Transmission TechnologyGlobal Energy Interconnection Research Institute Co. Ltd Beijing 102211 P. R. China
3. Institute for Superconducting and Electronic MaterialsUniversity of Wollongong Wollongong NSW 2522 Australia
4. Institute of Applied Physics and Materials EngineeringUniversity of Macau Macau 999078 P. R. China