A Comparison of Fast Neutron Irradiation Effects in Photoconductive and Photovoltaic InSb Infrared Detectors

The relative neutron irradiation hardness of photoconductive and photovoltaic InSb infrared detectors is examined for various operating modes and conditions. It is found that photoconductors are much less vulnerable to fast neutrons at 78K than are photovoltaic detectors. The damage mechanisms for photovoltaic detectors are increased leakage currents coupled with a decrease of minority carrier lifetime in the bulk region with a damage constant of 1.5 × 10-14 ¿m-2 n-1 cm2, while a carrier removal rate of 1.1 cm-1 is established for 14 MeV neutron-irradiated p-type InSb with an initial carrier concentration of ~3 × 1014 cm-3. It is shown that these changes in material parameters can be used to predict fast neutron damage under all realistic operating conditions. The effects of neutron irradiations on signal, noise, current-voltage characteristics and spectral response are discussed in detail.