Abstract
A model for the formation of β misfit dislocations in the first stages of relaxation in InxGa1−xAs/GaAs heterostructures is proposed. Each p dislocation is the result of the cross-slip of a threading dislocation linked to a pre-existing α misfit dislocation which thus turns at a right angle. The resulting configuration is made of either L-shaped tips lying in the interface plane or inclined-V tips which have glided into the substrate. This is explained by analysing the forces acting on the dislocations and taking into account their dissociated character. The equilibrium configuration of the inclined-V tips is the result of the balance between the line tension which tends to expel these tips into the substrate and the return force from the interface which tends to keep them in the interface.