We discuss the characteristics of impurity band conduction detectors prepared from epitaxial Si:Sb. These detectors are sensitive to infrared light at wavelengths between 2.5 and 40 μm and outperform the current state-of-the-art Ge:Be photoconductors for this wavelength range by a combination of a peak responsivity R=32 A/W, low noise equivalent power (NEP) =1.1×10−15 W/Hz1/2 (at a flux of 1012 ph/cm2 s), inherently low sensitivity to cosmic ray particles, and freedom from the anomalous behavior observed in photoconductors.