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.