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

Achieving\nhigh-performance lead sulfide quantum dot (PbS QD)-based\nphotodetectors requires enhanced carrier transfer, which inevitably\nleads to an increased dark current. Balancing a high photocurrent\nand low dark current is crucial. In this work, a bridge-trap structure\nconstructed by the atomic layer deposition of dual oxides is proposed\nto simultaneously enhance photoresponse performance and reduce dark\ncurrent. Through the sequential infiltration of Al<sub>2</sub>O<sub>3</sub> and TiO<sub>2</sub> with precisely controlled concentrations,\na photodetector with enhanced responsivity and detectivity across\nvisible to near-infrared regions is obtained. The precisely controlled\nAl<sub>2</sub>O<sub>3</sub> infiltration serves as a bridge between\nQDs, enhancing carrier transfer and increasing photocurrent. Meanwhile,\natomic decoration of minimal TiO<sub>2</sub> serves as a carrier trap,\nsignificantly reducing the dark current (7.0 × 10<sup>–10</sup> A). Furthermore, an array imager fabricated with the modified PbS\nQDs demonstrates clear imaging of designed patterns under both visible\nand infrared light.