1. Key Laboratory of New Energy and Rare Earth Resource Utilization of State Ethnic Affairs Commission, Key Laboratory of Photosensitive Materials & Devices of Liaoning Province, School of Physics and Materials Engineering, Dalian Minzu University, 18 Liaohe West Road, Dalian 11660, China
2. State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
3. Institute of Optics, University of Rochester, 275 Hutchison Road, Rochester, New York 14627, USA
4. Department of Applied Physics, KTH Royal Institute of Technology, SE-106 91 Stockholm, Sweden
5. State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, China
6. School of Metallurgy, Northeastern University, Shenyang 110819, China
7. Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden