Crack formation in III-V epilayers grown under tensile strain on InP(001) substrates

Abstract
A simple theoretical model is presented which allows one to predict the critical layer thickness for crack initiation in tensile strained III-V films grown onto (001)-oriented semiconductor substrates. The predictions of the model are shown to compare favourably with experimental observations made on Inx(GaAl)l-x As epitaxial layers grown on InP(001) substrates. Possible reasons to explain why epilayers which have only just exceeded this critical thickness show asymmetric crack distributions are also proposed. Finally, it is demonstrated that measurements of crack profiles and separations allow us to estimate the amount of stored elastic energy in such layers and to explain why the cracks are always seen to penetrate beyond the epilayer into the substrate.