Dual-Oxide Bridge-Trap Structure via Atomic Layer Infiltration for Enhanced Performance of Quantum Dot Photodetector

Achieving high-performance lead sulfide quantum dot (PbS QD)-based photodetectors requires enhanced carrier transfer, which inevitably leads to an increased dark current. Balancing a high photocurrent and low dark current is crucial. In this work, a bridge-trap structure constructed by the atomic layer deposition of dual oxides is proposed to simultaneously enhance photoresponse performance and reduce dark current. Through the sequential infiltration of Al₂O₃ and TiO₂ with precisely controlled concentrations, a photodetector with enhanced responsivity and detectivity across visible to near-infrared regions is obtained. The precisely controlled Al₂O₃ infiltration serves as a bridge between QDs, enhancing carrier transfer and increasing photocurrent. Meanwhile, atomic decoration of minimal TiO₂ serves as a carrier trap, significantly reducing the dark current (7.0 × 10^-10 A). Furthermore, an array imager fabricated with the modified PbS QDs demonstrates clear imaging of designed patterns under both visible and infrared light.