Understanding Aniline Surface Treatment of CdTe

摘要

Surface etching of CdTe under illumination in aqueous aniline-based solutions has been investigated. Analysis of treated samples shows the formation of crystalline Te on the CdTe surface. Analysis of bath and treatment conditions indicated the presence of aniline, Cl~- ions, dissolved O_2, consistent illumination and careful control of pH as critical for successful surface etching. A photocatalytic mechanism is proposed for the reaction, where CdTe is etched by H_2O_2 or similar, generated through reduction of dissolved O_2 by conduction band electrons and complemented by oxidation of aniline. The generated Te is stable in the bath and the treatment provides reproducible surfaces. CdTe/CdS devices of 12% conversion efficiency were processed with 30 min aniline treatments. The toxicity of aniline is a concern and criteria for possible substitutes are discussed.