The characteristics of 60° and 90° dislocations in GaAs/Si(100) thin-film heterostructures grown by metal-organic chemical-vapor deposition at 650C were studied. The misfit dislocation network consisted of approximately 60% of 90° dislocations, and 40% of closely-spaced pairs of 60° dislocations with intersecting glide planes. This ratio remained essentially constant after rapid thermal annealing (800C, 90s). It was supposed that these 60° dislocation pairs had parallel screw components and, as a result, they could not combine to form a 90° dislocation. Upon annealing, some of the 60° dislocation pairs split to form stacking faults; in agreement with an earlier model. Based upon these observations, a model was proposed in which a first set of 60° dislocations was generated from the undulated surface above a critical thickness. The second set of 60° dislocations was nucleated at a larger thickness and at the smoother surface. The Burgers vectors of these dislocations were controlled by dislocations from the first set, and only low-energy dislocation pairs were formed by glide towards the interface and, later, by short glide and climb along the interface plane. A numerical analysis, based upon elasticity theory, was used to evaluate changes, in the nucleation barrier for 60° dislocations, caused by interaction with existing misfit dislocations.

Formation of Misfit Dislocations in Thin Film Heterostructures. J.Narayan, S.Oktyabrsky: Journal of Applied Physics, 2002, 92[12], 7122-7