Passivation of AlGaSb/InGaAsSb/GaSb SWIR Detectors by Aqueous (NH 4 ) 2 S Solution, SiO 2 , and Ionic Liquid Encapsulation

We report on the development of a passivation technology for InGaAsSb nBp photodiodes incorporating an AlGaSb barrier, aimed at achieving bulk-limited leakage currents and enhanced detectivity in detectors with a photosensitive area of 0.01mm2. Following passivation with SiO2preceded by sulfidation, an increased yield of 113-$\mu $m-diameter diodes exhibiting improved zero-bias resistance (${R}_{{0}}\text {)}$was observed, particularly at lower temperatures reachable with thermoelectric coolers. At 215K, the dark current of devices of this size, with${R}_{{0}}$close to the average, was reduced by two orders of magnitude. At this temperature, the volume and surface generation rates of carriers were found to be equal for diodes with an average size of$150~\mu $m. Furthermore, we investigated alternative approaches, including backside illumination through the GaSb substrate, the integration with immersion optics, and the use of ionic liquid (IL)-based passivation technique.