Sensitization of lead selenide mid-IR photodetectors

This study intends to investigate and optimize the sensitization process required to create lead selenide, room temperature, mid-infrared, photodetector devices. This is intended to complement flow-limited field-injection electrostatic spray (FFESS) grown films, a promising chemical growth technique new to lead selenide. The sensitization step is designed to improve the room temperature photoresponse in the 1 μm to 5 μm wavelength range of lead selenide films. The process involves oxidation of the film followed by halogenation using iodine, after which photo-response can be measured using a four-point probe resistance measurement before and after illumination. To anneal the films in the proper ambient atmosphere, a tube furnace was fitted with a custom built gas generator to supply elemental iodine gas as well as nitrogen and air for oxidation. The mechanism behind sensitization of lead selenide using halogens is little understood, but a charge separation model exists to give some insight. Regardless, the parameters and layout of this step for films grown by specific processes must be determined experimentally. By optimizing this step, we managed to produce photo-conductors which showed 36.5 % change in resistance at 3V forcing voltage.U of I Onlyundergraduate senior thesis not recommended for open acces