The Early Stages of Quantum Dot Self-Assembly: A Kinetic Monte Carlo Simulation

The influence of a periodic strain field in a silicon substrate on the nucleation of surface atomic clusters is studied using a Kinetic Monte Carlo (KMC) model for Ge quantum dot formation. The effect of strain on island diffusion is determined by calculating the binding energy of an island with the Modified Embedded Atom potential. KMC simulations have been carried out on the basis of diffusion pathways on reconstructed Si surfaces and effective island diffusion kinetics. It is found that island diffusion coupled with surface stress fields play a dominant role in precisely forming atomic clusters during the early stages of evolution under an extremely weak inhomogeneous stain field. The results explain experimental observations on the ordering of Ge self-assembled quantum dos along underlying buried interfacial dislocation arrays in a relaxed 800 Å Si_0.85Ge_0.15 buffer layer.