Monolithic integration of spectrally selective uncooled lead selenide detectors for low cost applications

Abstract

We report the manufacture of an uncooled infrared detector with its natural spectral response modified as design. Thanks to a technology to process uncooled polycrystalline PbSe sensors, we have integrated a filter and a PbSe detector monolithically. Our processing is based on thermal deposition of a thin PbSe layer followed by a specific thermal treatment in an iodine-rich atmosphere that turns PbSe into an infrared sensitive material. Using this technique, we are able to process uncooled medium-wave infrared detectors directly on the last layer of an interference filter. After this achievement, polycrystalline PbSe detectors will be smarter, more reliable, and exhibit better characteristics than their direct competitors (near room-temperature cadmium mercury telluride, InAsSb, etc.). Standard photolithography, interference filter deposition, and dry etching techniques are fully compatible with this polycrystalline PbSe processing. These are essential facts in order to obtain reduced filter and detector sizes (multicolor arrays). The technology described in this work is useful in the field of low cost infrared detection.