Tin‐Lead‐Selenide Nanocrystals for Sensitive Uncooled Mid‐Infrared Focal Plane Array Imager with Monolithic Readout Integration

Abstract

Abstract The mid‐infrared focal plane array (FPA) imager has developed over recent decades to become multifunctional, powerful, reliable, miniaturized, and cost‐effective. However, the complexity of the refrigerated packaging process (such as dewar flask) and traditional fabrication technology (such as flip‐chip) continues to contribute significantly to the high cost of industrial production. Here, a simple, low‐cost, and effective type of uncooled mid‐infrared FPA imager is reported through the monolithic integration of mid‐infrared Pb 1‐x Sn x Se nanocrystals (NCs) PIN heterojunction (PbS/Pb 1‐x Sn x Se/ZnO) photodetectors and glass‐based readout integrated circuits (ROICs). Sn‐doping in PbSe NCs not only weakens the internal photocarrier‐phonon coupling to reduce thermal noise but also optimizes the energy band structure of the heterojunction to enhance mid‐infrared performance. Finally, the PbS/Pb 0.86 Sn 0.14 Se/ZnO heterojunction photodetector demonstrates a dark current (2.7 x 10 −7 A mm −2 at −0.5 V), a detectivity of 7.46 × 10 9 Jones at a peak wavelength of 4.25 µm, air stability (retaining 96.7% performance at 300 K for 360 days) and the corresponding uncooled mid‐infrared FPA (64 × 64 pixels) achieves excellent thermal sensitivity of 133 mK. These results underscore the substantial potential applications of mid‐infrared FPA based on the heterojunction, including spectral imaging, gas leak detection, and chemical reagent identification.