Lead Selenide Thin Films and Uncooled Midinfrared Detectors by Vapor Phase Deposition

The broad application of lead selenide (PbSe)-based uncooled midinfrared (MIR) detectors has been hindered by the nonuniformity of wafer-level films prepared by the conventional chemical bath deposition (CBD) method. Herein, using a vapor phase deposition (VPD) approach, we demonstrate the deposition of 3 in. wafer-scale uniform PbSe thin films with thicknesses of up to 1.5 μm. To trigger the MIR response, the as-grown films were sensitized at an elevated temperature in an oxygen-iodine atmosphere. We discovered that the key to spark off the MIR response of the PbSe detector originated from the self-assembled rodlike microstructures in the thin films, which can be controlled by the I₂/PbSe flux ratio in the VPD process. At room temperature, the thin film detector exhibits an excellent optoelectronic performance, with detectivity up to 2.4 × 10⁹ cm Hz^1/2 W^-1 achieved under optimized conditions. Our results show that the VPD method opens up a new avenue to the industrialization of uncooled lead-salt MIR detectors.