Coupled evolution of composition and morphology in a faceted three-dimensional quantum dot

We study the coupled dynamical evolution of composition and morphology of a two-component alloy quantum dot in a faceted three-dimensional geometry. Using SiGe/Si as a model system, we perform simulations on the facet evolution and transition from a pyramidal to a domed shape, coupled with compositional evolution at different growth rates. We find that the composition profile in the quantum dot is growth-history dependent, and the growth rate can significantly influence the distribution of Ge atoms, indicating the importance of growth kinetics. In addition, we find that the aspect ratio of the quantum dot is affected by the composition distribution, highlighting the importance of the coupling between morphology and composition. Our present work may be useful in controlling the composition and morphology of quantum dots for applications in high-performance electronic devices.