Kinetic Monte Carlo Simulations of Quantum Dot Self-Assembly

For many heteroepitaxial systems growth proceeds in the Stranski-Krastanov (SK) growth mode, where layer-by-layer growth is followed by the formation and growth of three-dimensional (3D) islands. These resulting 3D islands are often referred to as quantum dots (QDs). In this talk, we present detailed and systematic kinetic Monte Carlo (KMC) simulations to study the effects of key model parameters including strain, growth temperature, and deposition rate. We show that increasing the strain lowers the apparent critical thickness of the wetting layer that is defined by the onset of QD formation. Similarly, increasing the growth temperature lowers the apparent critical thickness, until intermixing, and the resulting relevance of entropic contributions, becomes more significant. Recent experiments for Ge QDs grown on InAlAs(111) show a transition from SK growth to Volmer-Weber (VW) growth (where QDs form before the formation of even a single wetting layer) as the substrate temperature increases. We use our KMC simulations to explain this unexpected behavior.