Long-term stability of ammonium-sulfide- and ammonium-fluoride-passivated CdMnTe detectors

Abstract

We evaluated the long-term stability of CdMnTe (CMT) detectors treated with ammonium-saltbased passivants. Passivation improved the detector’s stability and reduced the degradation of its energy resolution with time. Here, we stored passivated 5 × 5 × 9 mm3 CMT detectors in an ambient environment for 550 days and evaluated the effects of aging by measuring their pulse-height spectra over time. The CMT detector passivated with ammonium fluoride exhibited a higher leakage current after 550 days, and its performance was degraded accordingly. Our analyses of the leakage current for a pixelated CMT detector revealed that the edges and the corners of the detector were responsible for the higher leakage, which resulted from a degradation of the passivation layer in those areas. Assurance of the long-term stability and reproducibility of the detector necessitates that the edges and the corners be mechanically passivated following chemical treatment.