1. State Key Laboratory of Silicon Materials Cyrus Tang Center for Sensor Materials and Applications School of Materials Science and Engineering Zhejiang University Hangzhou 310027 China
2. Xiamen Institute of Rare Earth Materials Chinese Academy of Sciences Xiamen Fujian 361021 China
3. CAS Key Laboratory of Design and Assembly of Functional Nanostructures Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 China
4. Department of Physics University of North Texas Denton TX 76203 USA
5. Department of Chemistry University of Texas at San Antonio San Antonio TX 78249 USA