Optically Enhanced Carrier Trapping and Interfacial Tunneling for Low-Noise Broadband Photodetection Imaging

To address the challenges associated with dark current suppression, spectral response range, and carrier transport efficiency in photodetectors, this study presents a PbS QDs/3D-graphene/high-κ/Si heterojunction photodetector. The design combines advanced structural design with interfacial engineering, improving device performance. A high-κ dielectric layer (Al₂O₃) functions dual-purpose as an interfacial passivation layer and a tunneling barrier, mitigating dark current and noise. The three-dimensional (3D) graphene serves as an ultrabroadband light absorber with an intrinsic nanoscale resonant cavity, enhancing spectral response and light-trapping. Lead sulfide colloidal quantum dots (PbS QDs) function as carrier-trapping centers, minimizing rapid carrier recombination. The final device achieves a light absorption of 91%, operates self-powered across 380-2200 nm, and exhibits low dark current (0.7 nA), low noise current (3.1 × 10^-11 A·Hz^-1/2), a responsivity (R) of 67 A/W, and an impressive specific detectivity (D*) of 1.1 × 10¹³ Jones, with an external quantum efficiency (EQE) of 5348%. The device exhibits excellent stability (over 6 months), reproducibility (100 cycles), and fast response times (rise/fall times (t_r/t_f) of 232/238 μs). The photodetector was successfully applied in a 180 × 180 pixel imaging array, achieving a recognition accuracy of 99%. This platform paves the way for future advancements in optoelectronic device design and multimodal photodetection.