Quantum Dots Short-Wave Infrared Image Sensor with Enhanced Photoresponse Enabled by a Planar p–n Homojunction

Abstract

Quantum dots (QDs)-based photodetectors are promising alternatives to construct short-wave infrared (SWIR) image sensors at a low cost. Improving the photoresponse and scalability of QDs is important to enable their practical applications. In this work, we developed a complementary metal–oxide–semiconductor (CMOS)-compatible SWIR image sensor based on lead sulfide (PbS) quantum dots (QDs) utilizing a p–n homojunction photoconductor (PC) architecture. Through solution-phase ligand-exchanged PbS QDs treated by lead iodide (PbI₂) combined with a solid-state ligand-exchanged PbS QDs thin film treated with ethanedithiol (EDT), a p–n homojunction was constructed, enabling more efficient separation of photogenerated carriers and significantly enhancing the photoresponse. This approach allows for the monolithic integration of solution-processed QDs with silicon readout integrated circuits (ROICs), eliminating the need for complex flip-chip bonding and facilitating the fabrication of large-scale (640 × 512) QDs imagers. Consequently, the homojunction-based QDs SWIR imager delivers performance with low noise and a high average detectivity of 1.7 × 10¹⁰ Jones, and the capability to capture high-resolution SWIR images highlights its potential for diverse applications.