Trapping effects in HgCdTe

Abstract

Carrier trapping influences the performance of HgCdTe infrared detectors in the 8–12 μm range by enhancing tunneling currents, reducing excess carrier lifetimes, and increasing g–r and 1/f noise. In this work, the effects of carrier trapping on the tunneling currents in n+p diodes are calculated, and the dependence of the tunneling current on temperature, bias, doping level, and trap characteristics is illustrated. It is shown that by assuming the dominant trap energy to be at the Fermi level, the calculated tunneling currents exhibit many of the peculiar features which have been observed experimentally. The related effects that minority carrier traps have on the excess carrier lifetimes are also discussed, and a simple method of estimating many of the relevant trapping characteristics from lifetime measurements is presented.