IR detectors operated in a space environment are subjected to a variety of radiation effects while required to have very
low noise performance. When properly passivated, conventional mercury cadmium telluride (MCT)-based infrared
detectors have been shown to perform well in space environments. However, the inherent manufacturing difficulties
associated with the growth of MCT has resulted in a research thrust into alternative detector technologies, specifically
type-II Strained Layer Superlattice (SLS) infrared detectors. Theory predicts that SLS-based detector technologies have
the potential of offering several advantages over MCT detectors including lower dark currents and higher operating
temperatures. Experimentally, however, it has been found that both p-on-n and n-on-p SLS detectors have larger dark
current densities than MCT-based detectors. An emerging detector architecture, complementary to SLS-technology and
hence forth referred to here as nBn, mitigates this issue via a uni-polar barrier design which effectively blocks majority
carrier conduction thereby reducing dark current to more acceptable levels.
Little work has been done to characterize nBn IR detectors tolerance to radiation effects. Here, the effects of gamma-ray
radiation on an nBn SLS detector are considered. The nBn IR detector under test was grown by solid source molecular
beam epitaxy and is composed of an InAs/GaSb SLS absorber (n) and contact (n) and an AlxGa1-xSb barrier (B). The
radiation effects on the detector are characterized by dark current density measurements as a function of bias, device
perimeter-to-area ratio and total ionizing dose (TID).