The initial stages of Hg0.8Cd0.2Te anodization have been studied by electrochemistry and x‐ray photoelectron spectroscopy (XPS). Comparison of the polarization curves of HgCdTe, HgTe, and CdTe with XPS measurements of HgCdTe surfaces anodized to various potentials allows us to propose a possible model for the anodization. First the Hg‐rich surface layer formed by the bromine–methanol etch is removed at a potential of ∠−0.1 V vs SCE (standard calomel electrode). Upon oxidation of the Te2− at ∠+0.35 V vs SCE in an aqueous solution (at ∠+0.6 V vs SCE in an ethylene glycol solution) the Cd2+ and Hg2+ ions are released, with the Cd2+ reacting with the Te4+ and O2− to form CdTeO3 and CdTe2O5. Some of the Hg2+ is incorporated into the oxide in analogous compounds, but most is driven into solution. The dissolution of Hg proceeds in advance of the Te4+/Te2− interface, resulting in a depletion of Hg from the interfacial region of the semiconductor.

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