[1] Chinese Acad Sci, Shenzhen Inst Adv Technol, Shenzhen 518055, Peoples R China
[2] Univ Chinese Acad Sci, Beijing 100049, Peoples R China
[3] Univ Sci & Technol China, Nano Sci & Technol Inst, Suzhou 215123, Peoples R China
[4] Chinese Univ Hong Kong, Dept Elect Engn, Hong Kong, Hong Kong, Peoples R China
[5] Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA