Nano-Oxide-Assisted Si/PbS CQD Heterojunction Photodetectors for Broadband Sensing

The integration of Si with PbS colloidal quantum dots (CQDs) in photodetectors (PDs) holds immense potential for wide-range wavelength detection, cost-effective fabrication, and industrial scalability. However, challenges arise from suboptimal contact and limited carrier transport between these materials. To overcome these challenges, we have proposed the utilization of a nano-oxide-assisted layer grown through atomic layer deposition on the surface of PbS CQDs. This surface modification introduces trap states that facilitate carrier transport, resulting in enhanced performance and additional gain. With the incorporation of the nano-oxide layer, the PD demonstrates effective operation within the wavelength range from 600 to 1600 nm. Notably, it achieves an impressive external quantum efficiency (EQE) of 156% at 1530 nm, accompanied by a specific detectivity (D $^\ast$ ) of 2.0 $\times$ 10 $^{\text{11}}$ Jones and a rapid response time of 227 $\mu $ s. The introduction of the nano-oxide modification brings forth numerous advantages, including exceptional performance, straightforward processing, and cost-effectiveness. This remarkable solution paves the way for the realization of single-chip integrated broadband sensing.