1. State Key Laboratory for Optoelectronics Materials and Technology; Sun Yat-sen University; Guangzhou 510275 China
2. School of Metallurgy Engineering; Central South University; Changsha 410008 China
3. School of Material Science and Engineering; Southwest University of Science and Technology; Mianyang 621010 China
4. Thin Film Optoelectronics Technology Center; Shanghai Advanced InstituteChina Academy of Science; Shanghai 200400 China