Process technology to integrate polycrystalline uncooled PbSe infrared detectors on interference filters

摘要

A technology to process uncooled polycrystalline PbSe IR detectors on interference filters has been developed. Thus, the lead salt natural spectral response can be modified as required. PbSe is deposited, processed and sensitized, following a unique method, on an interference filter made up of a sapphire or silicon substrate and a Ge/SiO multilayer structure. Unlike standard polycrystalline PbSe processing methods, we deposit PbSe by sublimation in vacuum. As-deposited, PbSe is not sensitive to infrared light. In order to turn it photosensitive it is necessary to expose the films to specific thermal treatments. We have developed a very efficient sensitization process during which substrates are submitted to temperatures as high as 450℃. In this work we demonstrate that we are able to process a PbSe detector directly on top of an interference filter. Also, we present preliminary results regarding the compatibility of our technology with standard photolithography and dry etch techniques. Results obtained pave the way for the development of uncooled multicolor medium-wave infrared detectors.