The nature of dislocation sources and strain relief in InAs yP 1− y films grown on 〈100〉 InP substrates

Abstract

The nature of dislocation sources in a compressively strained InAs 0.48P 0.52 layer grown on a (100) InP substrate by gas source molecular beam epitaxy has been studied. Head's solution for an edge dislocation lying parallel to a free surface in an elastically isotropic, semi-infinite solid is used to evaluate the energetics of the one-dimensional dislocation arrays observed to form in the easy glide [01 1 ] direction prior to activation of sources which glide and cross-slip on {111} and {110}. The same solution is also used to derive the displacements of a misfit dislocation at the epilayer-substrate interface, and to characterize the origin of the diffraction contrast observed at the misfit dislocations in plan view TEM. Each source is shown to emit four sets of different dislocations. The effective stress acting on {111} and {110} during the first stages of activation of these dislocation sources has been determined.