Two-colour In0.5Ga0.5As quantum dot infrared photodetectors on silicon

An InGaAs quantum dot (QD) photodetector is directly grown on a silicon substrate. GaAs-on-Si virtual substrates with a defect density in the order of 106 cm−2 are fabricated by using strained-layer superlattice as dislocation filters. As a result of the high quality virtual substrate, fabrication of QD layer with good structural properties has been achieved, as evidenced by transmission electron microscopy and x-ray diffraction measurements. The InGaAs QD infrared photodetector is then fabricated on the GaAs-on-Si wafer substrate. Dual-band photoresponse is observed at 80 K with two response peaks around 6 and 15 μm.