Enhanced photon-generated carrier extraction from Si nanostructure under additional infrared light irradiation

Recombination and trapping effect in quantum dots are large barriers to efficient photon-generated carrier extraction. In this paper, Infrared (IR)-assisted carrier extraction in a Si/SiO2 multiple quantum well is demonstrated. Operated at reverse bias, enhanced photoresponse from 300 to 700 nm is observed. External quantum efficiency nearly 200% is obtained when both visible light and IR are added. The enhancement is attributed to potential modulation by photo-illumination. A theoretical model including three processes is presented to explain this conclusion. The secondary light source IR could excite trapped carriers from the defects at the Si/SiO2 interface, improving extraction efficiency.