We have investigated the properties of Hg 0.8 Zn 0.2 Te surfaces after passivation with various treatments, either by electrochemical processes or by immersion in chemical baths. From the C (V ) characteristics of metal-insulator-semiconductor structures, we have determined the density of fixed interface charges deduced from the flat-band voltage. The density of slow traps is obtained from the width of the anticlockwise hysteresis and the energy distribution of fast interface states is reported for all passivation processes. The treatment by immersion in bromine-methanol solution including a small amount of Na 2 S gives the best interface properties. The energy distribution of fast interface states then presents a broad U-shape with a minimum lower than 5 × 10 10 eV −1 cm −2 . The surface roughness as measured by atomic force microscopy is notably reduced after this treatment and the x-ray photoelectron spectroscopy of the samples so obtained reveals the presence of a residual Te layer on the surface.

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