The microstructures of films, grown by molecular beam epitaxy at low temperatures and δ-doped with Sb, were studied by means of transmission electron microscopy. The material contained 0.5at% of excess As which precipitated during post-growth annealing. The Sb δ-doping was found to affect strongly the microstructure of the precipitates (clusters) and their ripening-rate during annealing. Segregation of Sb in the clusters was revealed. In contrast to the well-known pure As clusters, the As–Sb clusters introduced strong local deformations into the surrounding GaAs matrix. Up to a threshold diameter of 7 to 8nm, the clusters and surrounding matrix were coherently strained. Larger clusters were associated with dislocation loops of interstitial type. The relaxation of local strains via the formation of dislocation loops was studied experimentally and theoretically.

Local Stresses Induced by Nanoscale As–Sb Clusters in GaAs Matrix. V.V.Chaldyshev, N.A.Bert, A.E.Romanov, A.A.Suvorova, A.L.Kolesnikova, V.V.Preobrazhenskii, M.A.Putyato, B.R.Semyagin, P.Werner, N.D.Zakharov, A.Claverie: Applied Physics Letters, 2002, 80[3], 377-9