Origin of Self-Assembled Quantum Dots in Highly Mismatched Heteroepitaxy

In the early stages of highly mismatched heteroepitaxy, self-assembled dots appear as soon as the coverage exceeds a critical value. It is shown that this phenomenon is determined by the preliminary growth of 2D platelets which act as precursors for the formation of 3D coherent islands. The argumentation is based on a total energy calculation using a valence force field approach for the elastic part, the surface contribution being added separately. The proposed mechanism provides an explanation for the fairly good calibration of the observed 3D islands.