The interface chemistry of HgCdTe passivated with native sulfide layers grown from nonaqueous and aqueous polysulfide solutions

Abstract

We have grown anodic sulfide passivation layers on HgCdTe from both nonaqueous and aqueous polysulfide solutions. In both cases CdS layers are nominally obtained. The growth behavior of the sulfide layers is found to be quite different in the different electrolytes. Capacitance–voltage measurements on metal-insulator semiconductor device structures that incorporated a ZnS cap and Pd gate metal over the CdS have been used to compare the electrical properties of the interfaces produced. Preliminary evidence suggests that aqueous anodic sulfide layers may be more stable than nonaqueous ones, but contain more positive fixed charge and mobile ion charge. Auger electron spectroscopy depth profiles indicate that the aqueous anodic sulfides are oxide free, but appear to contain more Hg and Te contamination than nonaqueous anodic sulfides.