[1] S China Normal Univ, Inst Optoelect Mat & Technol, Guangdong Engn Res Ctr Optoelect Funct Mat & Devi, Guangdong Prov Key Lab Nanophoton Funct Mat & Dev, Guangzhou 510631, Guangdong, Peoples R China
[2] Sun Yat Sen Univ, Sch Phys & Engn, State Key Lab Optoelect Mat & Technol, Guangzhou 510275, Guangdong, Peoples R China