1. Research and Development Center for Solid State Lighting, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
2. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
3. Beijing Engineering Research Center for the 3rd Generation Semiconductor Materials and Application, Beijing 100083, China
4. CrayoNano AS, Sluppenvegen 6, NO-7037 Trondheim, Norway
5. Department of Electronic Systems, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway