CROSS-SLIP IN THE 1ST STAGES OF PLASTIC RELAXATION IN INXGA1-XAS GAASHETEROSTRUCTURES

A model for the formation of beta misfit dislocations in the first sta ges of relaxation in InxGa1-xAs/GaAs heterostructures is proposed. Eac h beta dislocation is the result of the cross-slip of a threading disl ocation linked to a pre-existing alpha misfit dislocation which thus t urns at a right angle. The resulting configuration is made of either L -shaped tips lying in the interface plane or inclined-V tips which hav e 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 t hese tips into the substrate and the return force from the interface w hich tends to keep them in the interface.