Thermal etching of binary and ternary III–V compounds under vacuum conditions

Abstract

A thermodynamic approach was applied to the analysis of thermal etching of both binary and ternary III–V compounds in vacuo. Two different regimes of etching based on the congruent and on the non-congruent vaporization, may be distinguished. The latter regime requires an external group V component flux to prevent the material decomposition. This regime can provide etching rates of 0.1–5.0 ML/s for GaAs and InAs. The maximum etching rate is found to be limited by the liquid phase formation on the surface. The calculated data are compared with experiment performed by the RHEED intensity oscillation method for GaAs. In the case of steady state etching of ternary compounds (AlGaAs and InGaAs) the surface is depleted significantly by the more volatile species.