State Key Laboratory of Optoelectronic Materials and Technologies;
School of Physics;
Sun Yat-sen University;
510275 Guangzhou;
China;
Department of Electrical and Computer Engineering;
National University of Singapore;
4 Engineering Drive 3;
Singapore 117583;
Singapore;
NUS Suzhou Research Institute(NUSRI);
Suzhou Industrial Park;
215123 Suzhou;
China;