ABSTRACT
The strain relief in InxGa1-xAs/GaAs (111)B (x>0.25) presents a singular typology with the formation of a triangular star-like misfit dislocation configuration. To study the generation of this dislocation configuration, double quantum well structures with different barrier thicknesses were grown. A change in the barrier thickness between the double quantum wells imposes a modest change in the average misfit strain and allows us to approach little by little the start of plastic relaxation in this type of heterostructure. An adapted double kink Matthews model of the critical layer thickness satisfactorily explains this behaviour. We have observed that this misfit dislocation configuration does not form from threading dislocations coming from the substrate, but from the elongation of treading dislocation groups with their origin in defects at the bottom interface of the first QW. The study of the nature and formation of these defects constitutes the first stage to gain an understanding of the plastic relaxation in this type of structure.
