AN X-RAY PHOTOELECTRON SPECTROSCOPIC STUDY OF CHEMICAL ETCHING AND CHEMOMECHANICAL POLISHING OF HGCDTE

A study of chemical etching and chemo-mechanical polishing of Hg 0.8Cd0.2Te (MCT) with bromine-methanol has been carried out. It was found that the etch rate could be controlled down to 0.1 nm/s when 0.001% of bromine-methanol was used. Surface analysis using x-ray photoelectron spectroscopy indicated that differential etching of the constituents and accumulation of elemental tellurium occurred even when only a few monolayers were etched from a stoichiometric MCT surface. The relative etch rates were determined to be Cd≫ Hg≳Te. Nevertheless, it was found that chemo-mechanical polishing could produce smooth surfaces with no significant accumulation of elemental tellurium. The production of such surfaces, however, required a balance of chemical etching and mechanical lapping. Furthermore, quick quenching of chemical etching was also required after chemo-mechanical polishing in order to prevent further surface degradation.