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

The effects on the strain relaxation kinetics of a thin buffer layer's mech anical response and of the epitaxial film compositional grading are investi gated in the epitaxial growth of InAs on GaAs(111)A. Two heteroepitaxial sy stems are analyzed, consisting of thin and thick GaAs buffer layers grown o n GaAs(111)A epi-ready substrates. In both cases, one monolayer of In0.50Ga 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 i s measured as a function of film thickness. The experimental measurements a re described successfully by a phenomenological mean-field theoretical anal ysis. Our results support that the mechanical response of a thin buffer lay er is similar to that of a thin compliant substrate that is unconstrained a t its base. Furthermore. our results indicate that the mechanical behavior of a thin buffer layer can be used in conjunction with film compositional g rading toward strain relaxation engineering in semiconductor heteroepitaxy. (C) 2000 Elsevier Science B.V. All rights reserved.