Solution processable PbS quantum dots/silicon multispectral detectors

Colloidal quantum dots (QDs) have been considered in the last years as a promising material for photodetectors due to size-tunable optical absorption spectra through quantum size effect. Another important advantage is solution processability that facilitates integration on a large variety of substrates, including silicon. This paper presents a hybrid PbS/silicon device prepared from solution-processed PbS quantum dot film on top of a Ti-Au/Si device. The complex architecture of the device, combining a PbS photoconductor, a silicon based metal-semiconductor-metal (MSM) detector and a heterojunction p-PbS QDs/n-Si ensures a very good collection of the photogenerated carriers, a long carrier life time, and consequently high responsivity. The hybrid device exhibits a broad spectral range, from ultraviolet to short-wave infrared with responsivities up to 110 A/W, detectivities up to 10
¹³
Jones and a good stability in time. The broad spectral response of these photodetectors makes them useful for multispectral applications.