Design principles were developed for stacks of epitaxial layers with differing lattice parameters. The thickness and composition of each layer was determined by using a method which was aimed at reducing the likelihood of edge dislocation formation within the epilayer. This was done by ensuring that the 60 dislocations at each interface were so separated that dislocation glide along {111} planes to form an edge dislocation required the traversal of another interface. This implied that the two 60 dislocations which could glide so as to form an edge dislocation would have to interact with the dislocation array in the InGaAs/InGaAs interface. Such interactions would reduce the numbers of edge dislocations that were created in the structure. The suppression of edge dislocations was important because they were sessile and could block gliding threading dislocations; thus trapping them within the layer and reducing the extent of strain relief.

G.MacPherson, R.Beanland, P.J.Goodhew: Philosophical Magazine A, 1996, 73[5], 1439-50