Two-dimensional phase-field simulation of self-assembled quantum dot formation

The morphological evolution of a strained heteroepitaxial thin film of Si1−xGex/Si during deposition has been investigated by two-dimensional (2D) phase-field simulations. The phase-field model developed can form facet morphologies that are modeled using the generalized gradient correction coefficient for a crystal with a high anisotropy of surface energy, and can simulate the sequential shape transitions well known in the Si1−xGex/Si(0 0 1) system: a 2D wetting layer, faceted three-dimensional pyramids, and multifaceted domes. The effects of Ge composition and mobility on island formation and island evolution have also been studied. Some typical and important phenomena observed in previous experimental studies during Si1−xGex/Si(0 0 1) heteroepitaxy have been simulated using the phase-field model.