The structures of 2 layers which were 13 or 327nm thick, and grown by metal-organic vapour phase epitaxy onto a GaAs(001) substrate, were studied by means of high-resolution X-ray diffraction. The large lattice mismatch was largely relaxed by regular arrays of 90º dislocations. The results showed that both layers had orthorhombic structures. Scattering data showed that these dislocations were localized at the interface, and that both the layer and substrate were distorted. The spacings of the dislocations were different along the  and [1¯10] directions; showing that the 90º dislocations were less effective at removing the strain in the  direction. This was also the direction in which islands grew largest, and the direction in which the mosaic spread of the thick sample was largest. It was concluded that more of the strain in this direction was taken up by 60º dislocations than was the case in the [1¯10] direction.
X-Ray Scattering, Dislocations and Orthorhombic GaSb A.Y.Babkevich, R.A.Cowley, N.J.Mason, A.Stunault: Journal of Physics - Condensed Matter, 2000, 12, 4747-56