Asymmetric tilt interface induced by 60° misfit dislocation arrays in GaSb/GaAs(001)

Transmission electron microscopy of GaSb film grown on (001) GaAs revealed regular 60° misfit dislocation arrays in abnormally large and irregularly shaped GaSb islands. Having a same orientation of the Burgers vector, the 60° dislocations induce an asymmetric tilt interface. Calculations using anisotropic elasticity show that this interface has lower elastic energy than the symmetric interface relaxed by 60° dislocations of alternating orientations. When 60° dislocations are generated at the leading edge of growing islands, a particular orientation that assists the bending of atomic planes to the free surface of islands is preferred for a partial elastic relief of the misfit strain.