[1] Guangdong Univ Technol, Expt Teaching Dept, 100 Waihuanxi Rd, Guangzhou 510006, Guangdong, Peoples R China
[2] Sun Yat Sen Univ, Sch Phys & Engn, State Key Lab Optoelect Mat & Technol, Guangzhou 510275, Guangdong, Peoples R China
[3] Chinese Univ Hong Kong, Dept Elect Engn, Shatin, Hong Kong, Peoples R China
[4] Chinese Univ Hong Kong, Mat Technol Res Ctr, Shatin, Hong Kong, Peoples R China