Solution-Based PbS Photodiodes, Integrable on ROIC, for SWIR Detector Applications

Photodiodes, based on PbS colloidal quantum dots (CQD), are realized on both silicon substrates and the replicas of the read-out integrated circuits (ROICs) to demonstrate the first, fully integrated focal plane arrays. Careful optimization of PbS CQD film formation and ligand exchange process, together with optimized process steps, resulted in high performance, monolithically integrable photodiodes. High quantum efficiencies of 32% are achieved for photodiodes on Si substrates and high responsivities up to 5.73 A/W is achieved for photodiodes on ROIC replicas. These detectors achieved very high, normalized detectivities of 1.36 × 10¹¹ Jones and 1.42 × 10¹² Jones under 1 and 2-V reverse bias, respectively, that are close to conventional InGaAs short wave infrared detectors.