1. College of Materials Science and Engineering Shenzhen University Shenzhen 518055 P. R. China
2. College of Physics and Optoelectronic Engineering Shenzhen University Shenzhen 518060 P. R. China
3. Joint Key Laboratory of the Ministry of Education Institute of Applied Physics and Materials Engineering University of Macau Avenida da Universidade Taipa Macau SAR P. R. China