Effective Surface Passivation of CdMnTe Materials
Passivation is an important process that reduces surface leakage current and its attendant noise. We treated detector-grade large-volume CdMnTe:In samples with an (NH4)-based passivant, and compared the results with untreated samples by measuring current–voltage characteristics, surface recombination velocity, Raman spectroscopy, and charge-collection mapping. The leakage current of the passivated CdMnTe (CMT) detectors decreased five to ten times, and surface recombination declined five to six times, depending on the passivation conditions applied. We satisfactorily explained these improvements in detector performance as resulting from different passivation layers that were generated by distinct chemical reactions, as determined by the pH of the passivant.