Effects of buffer layer thickness and film compositional grading on strain relaxation kinetics in InAs/GaAs(111)A heteroepitaxy

Abstract

The effects on the strain relaxation kinetics of a thin buffer layer's mechanical response and of the epitaxial film compositional grading are investigated in the epitaxial growth of InAs on GaAs(111)A. Two heteroepitaxial systems are analyzed, consisting of thin and thick GaAs buffer layers grown on GaAs(111)A epi-ready substrates. In both cases, one monolayer of In 0.50Ga 0.50As is grown initially on the buffer layer followed by growth of several monolayers of InAs. In both systems, strain relaxation in the grown film is measured as a function of film thickness. The experimental measurements are described successfully by a phenomenological mean-field theoretical analysis. Our results support that the mechanical response of a thin buffer layer is similar to that of a thin compliant substrate that is unconstrained at its base. Furthermore, our results indicate that the mechanical behavior of a thin buffer layer can be used in conjunction with film compositional grading toward strain relaxation engineering in semiconductor heteroepitaxy.