Characteristics of dislocations at strained heteroepitaxial InGaAs/GaAs interfaces

The formation, interaction, and propagation of misfit dislocations in molecular-beam epitaxial InGaAs/GaAs heterointerfaces have been studied by transmission electron microscopy. With the lattice mismatch less than 2%, most of the interfacial dislocations are found to be 60° mixed dislocations introduced by glide processes. Sessile edge-type dislocations can also originate from the combination of two 60° mixed dislocations. The ratio of densities of edge dislocations to 60° dislocations was increased during the later part of the elastic strain relaxation. These sessile edge dislocations may be generated in appreciable numbers through a climb process. For large lattice-mismatched systems, the majority of the misfit dislocations are pure edge dislocations and high threading dislocation density is generally found. The interfacial dislocation network is found to contain regions of dislocations with the same Burgers vector that extend over several micrometers. The results support a mechanism that involves misfit dislocation multiplication during the molecular-beam epitaxial growth process.