1. Sino‐Russian International Joint Laboratory for Clean Energy and Energy Conversion Technology College of Physics & International Center of Future Science Jilin University Changchun 130012 P. R. China
2. State Key Laboratory for Superlattices and Microstructures Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 P. R. China
3. State Key Laboratory on Integrated Optoelectronics College of Electronic Science and Engineering Jilin University Changchun 130012 P. R. China