Plasmonic-Cavity Coupling for Ultrafast Response and Broadband Detection in PbSe Midwave Infrared Photodetectors

Uncooled midwave infrared (MWIR, 3–5 μm) PbSe photodetectors (PDs) have attracted increasing attention owing to their lightweight form factor, low power consumption, and scalable operational stability. However, achieving high performance in miniaturized pixels remains a major challenge, as planar architectures suffer from limited absorption and carrier transport efficiency and photonics-enabled enhancement strategies for chalcogenide-based devices remain insufficiently explored. Here, we report a CMOS-compatible PbSe thin film grown by magnetron sputtering coupled to a resonant metasurface-cavity absorber. Electromagnetic design yields near-unity absorptance in simulation, while fabricated metasurface-cavity-enhanced PbSe devices exhibit a broadband absorption enhancement of ∼500% relative to planar PbSe controls across the MWIR regime, achieving a peak absorptance of 83.77%. This enhanced light–matter interaction enables a high responsivity of 336 mA·W1– and a detectivity of 2.52 × 109 Jones at 3.3 μm, while maintaining an ultrafast response time of 5 μs. Furthermore, the detector also exhibits broadband sensitivity extending from the visible to the near-infrared, delivering a maximum responsivity of 5.64 A·W1– and a detectivity of 4.23 × 1010 Jones, along with pronounced blackbody sensitivity. This work not only demonstrates room-temperature, high-sensitivity, broadband detection in a scalable platform but also highlights the potential of nanophotonic-chalcogenide integration for advancing uncooled infrared technologies and enabling large-area MWIR optoelectronic applications.