Interface electrical characteristics of passivation films on HgCdTe

Abstract

A new passivation film: evaporated CdTe/ZnS combination film was grown on HgCdTe and the interface was characterized by capacitance-voltage (CV) characteristics of metal-insulator- semiconductor (MIS) test structures. Under proper processing conditions, the interface electrical parameters are: density of fixed charge approximately -4.0 X 1010 cm-2, density of slow state approximately 5.1 X 1010cm-2, density of fast interface state approximately 2.7 X 1011cm-2eV-1, and the time stability is good. These results show CdTe/ZnS double layer film is suitable for passivation of HgCdTe infrared detectors. We have also investigated single layer ZnS and anodic oxide/CdTe/ZnS triple layer film and found that the time stability of ZnS isn't good, and there exists too high density of fixed positive charge at the triple layer film//HgCdTe interface.