Design, Annealing, and Electric Field Effects on Proton and Gamma Irradiated MWIR HgCdTe Focal Plane Arrays

Abstract

This work presents the performance degradation under irradiation of multi pixel-designs n/p mid-wavelength infrared HgCdTe focal plane arrays (FPA). Gamma and proton irradiations are conducted to single out the effects of total ionizing dose (TID) from the damage induced by displacement damage dose (DDD). The radiation-induced degradation is analysed through the current levels evolution and the random telegraph signal (RTS) phenomenon. TID damages the silicon read-out integrated circuit (ROIC), causing low current level and RTS pixels. The influence of photodiode size and electric field on TID-induced defects is investigated. The results suggest that leakage currents in the ROIC, induced by TID, are involved. DDD impacts the HgCdTe photodetection layer: the number of pixels with high dark current and RTS is increased in the FPA. The amount of DDD-induced degradation scales with the photodiode size and the applied bias. This suggests that the defects responsible for the evolution of the dark current and RTS are located in the HgCdTe depletion region. Annealing mechanisms of these effects indicate different types of DDD-induced defects.