grown on relaxed SiGe buffer layers were investigated for the relationship between the misfit strain built in dots and nucleation sites. The strain fields of arrays of buried dislocations in a relaxed SiGe buffer layer provided preferential nucleation sites for quantum dots. Burgers vector analyses, using plan-view transmission electron microscopy, verified that the preferential nucleation sites of Ge self-assembled quantum-dots depended upon the Burgers vector direction of the corresponding dislocations. Measurement of the lateral distance between self-assembled quantum-dots and dislocations clarified that the location of self-assembled quantum-dots was at the intersection of the dislocation slip-plane and the top surface. The samples were fabricated so as to contain low dislocation densities. The average dislocation spacing was greater than the surface migration length of Ge adatoms; resulting in 2 groups of self-assembled quantum dots: those that were located along the dislocations and those that were not. Atomic force microscopic observations revealed distinctly larger critical size for Ge self-assembled quantum-dots grown over the intersection of the dislocation slip plane and the
top surface, than those grown in the regions between dislocations. The experimental observations indicated that the critical size of the pyramid-to-dome transition was strongly dependent upon the misfit strain in self-assembled quantum dots, with a lower strain being associated with a larger critical size.

Influence of a Buried Misfit Dislocation Network on the Pyramid-to-Dome Transition Size of Ge Self-Assembled Quantum Dots on Si(001). H.J.Kim, J.Y.Chang, Y.H.Xie: Journal of Crystal Growth, 2003, 247[3-4], 251-4