Effect of passivation coating on the HgCdTe heterostructures stability at elevated storage temperature

Abstract

Abstract. It was shown that the concentration of charge carriers and the stoichiometry of near-surface region are changed in p-type HgCdTe films with non-passivated and soiled by indium surface under storage temperatures 80°C and 120°C. The concentration of holes increased up to 1024  cm  −  3 and mobility dropped up to 12  cm2  /    (  V  ×  s  )   under heating. From acquired Auger spectra, it was obtained that the mercury concentration decreased but the cadmium concentration increased in near-surface region as the indium spot approached. The surface passivation by photoresist prevented these degradation processes. The current–voltage characteristics of p-n junctions around the indium spots on the surface of p-type HgCdTe films passivated by SiO2  /  Si3N4 layers were measured after storage temperatures from 60°C up to 120° C. It was found that the p-n junctions closest to the indium spots have an increased dark current. The usage of an additional passivation layer of anodic oxide suppressed the appearance of regions with increased dark currents. It was concluded that the additional passivation layer of anodic oxide is necessary for durable and stable work of infrared detector arrays based on HgCdTe films.