1. State
Key Laboratory for Optoelectronics Materials and Technology and School
of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275, People’s Republic of China
2. School
of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, People’s Republic of China
3. School
of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245, United States