State Key Laboratory of Optoelectronic Materials and Technologies School of Electronics and Information Technology Sun Yat-sen University Guangzhou 510275 People's Republic of China;
State Key Laboratory of Optoelectronic Materials and Technologies School of Physics Sun Yat-Sen University Guangzhou 510275 People's Republic of China;
Institute of Applied Physics and Materials Engineering University of Macau Avenida da Universidade Taipa Macau People's Republic of China;