[1] Huazhong Univ Sci & Technol, Sch Opt & Elect Informat, Wuhan Natl Lab Optoelect, Wuhan 430074, Peoples R China
[2] Harbin Normal Univ, Coll Chem & Chem Engn, Harbin 150025, Peoples R China
[3] Chinese Acad Sci, Inst Semicond, State Key Lab Superlattices & Microstruct, Beijing 100083, Peoples R China