THERMAL ETCHING OF BINARY AND TERNARY III-V COMPOUNDS UNDER VACUUM CONDITIONS

A thermodynamic approach was applied to the analysis of thermal etchin g of both binary and ternary III-V compounds in vacuo. Two different r egimes of etching based on the congruent and on the non-congruent vapo rization, may be distinguished. The latter regime requires an external group V component flux to prevent the material decomposition. This re gime 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 format ion on the surface. The calculated data are compared with experiment p erformed by the RHEED intensity oscillation method for GaAs. In the ca se of steady state etching of ternary compounds (AlGaAs and InGaAs) th e surface is depleted significantly by the more volatile species.