Antimony-mediated control of misfit dislocations and strain at the highly lattice mismatched GaSb/GaAs interface

Determining the atomic structure of misfit dislocations at highly lattice mismatched interface is essential to optimize the quality of the epitaxial layer. Here, with aberration corrected scanning transmission electron microscopy at sub-Angstrom resolution and molecular dynamics simulation, we investigated the atomic structure of misfit dislocations at GaSb/GaAs interface. New types of Lomer misfit dislocation formed on an Sb wetting monolayer were observed, in contrast to a conventional misfit dislocation whose core is located at interface. These Sb-mediated dislocations have highly localized cores and offer more capability to confine the mismatch strain at the interface. The low strain atomic configuration of Sb-mediated dislocations is driven by minimization of the core energy. This unveiled mechanism may pave the way to the growth of high quality hetero-epitaxial layers.