Infrared detectors using Schottky Barriers of near noble metal silicides have shown rapid improvements in the past five years. The sensing mechanism of these detector elements is internal photoemission over the energy barrier formed between the metal silicide and the silicon substrate. By lowering the barrier potential the Schottky photoresponse can be extended further into the infrared. This paper reports on a new barrier material, IrSi, which has a barrier height of less than 0.160 ev. This lower barrier improves the infrared performance in two ways. First, this structure will cover the entire 3.0 to 5.0 micrometer region. Secondly, the nature of Schottky photoemission is such that an increase in the long wavelength cutoff leads to increases in sensitivity at all shorter wavelengths.