Characterization of CdTe Growth on GaAs Using Different Etching Techniques

Abstract

CdTe buffer layers which were grown on (211)B GaAs by molecular beam epitaxy were subjected to two different etch treatments to quantify the crystal quality and dislocation density. The optical properties and thicknesses of the samples were obtained by ex situ spectroscopic ellipsometry. The surface morphologies of the CdTe epilayers were analyzed by atomic force microscopy, scanning electron microscopy, and Nomarski microscopy before and after chemical etching. We compare the triangle- and trapezoid-shaped etch pits due to the Everson and Nakagawa etch solutions, respectively. Measured etch pit density (EPD) values of triangle etch pits were found in the 8 × 10⁷ cm⁻² to 2 × 10⁸ cm⁻² range, and trapezoid-shaped etch pits were found in the 1 × 10⁷ cm⁻² to 7 × 10⁷ cm⁻² range for samples with thicknesses <2 μm.