Slow-Polishing Iodine-Based Etchant for CdTe and CdZnTe Single Crystals

We report on new etching solutions for treatment of CdTe and CdZnTe surfaces based on the iodine-emerging etchant composition KIO₃–KI–citric acid (C₆H₈O₇). CdTe samples with (111), (110), and (100) orientations, and also Cd_1?x Zn _x Te (x?=?0.04, 0.1) samples with (111), (110), (100), and (211) orientations were investigated. The dissolution rate was determined as a function of solution composition, etchant storage time, disc rotation speed, and temperature. It was established that this chemical dissolution is diffusion controlled. Study of the chemical composition and structure of (211)B Cd_1?x Zn _x Te surfaces etched under different conditions was carried out. x-Ray photoelectron spectroscopy measurements showed that a stoichiometric surface was achieved after briefly heating the etched surface in a vacuum. Reflection high-energy electron diffraction measurements revealed a high-quality single-crystalline surface layer in samples etched with KIO₃–KI–citric acid solutions as compared with those etched with a bromine–methanol treatment. The etching compositions were shown to be useful for controlled removal of semiconductor material, and also for chemical polishing of CdTe-based surfaces.