Study of intermixing effects in Ge/Si(001) growth using kinetic Monte Carlo simulations

The morphology of spontaneously self-assembled quantum dots in the Ge/Si(100) heteroepitaxial systems is affected by intermixing of silicon from the substrate with germanium from the deposited film. This is incorporated in an existing kinetic Monte Carlo simulation for strained heteroepitaxial growth through additional processes involving exchange of Si and Ge atoms at the interface. This exchange processes is governed by an intrinsic barrier that is modified by the local bond energy and the elastic energy. The simulations show clearly how intermixing reduces the strain and slows down the formation of quantum dots in the system. Composition maps are used to clearly establish the coupling between strain and intermixing. Silicon from the substrate replaces Ge atoms in the film in the core region of the quantum dot. This is the region with the maximum strain, and other regions with lower strain such as the periphery of the dots have much larger Ge fraction. These results showcase the method here as a powerful tool for study of intermixing in crystal growth.

Automated summary

The morphology of self-assembled quantum dots in Ge/Si heteroepitaxial systems is influenced by the intermixing of silicon and germanium. Simulations demonstrate that intermixing reduces strain and slows down the formation of quantum dots. Composition maps provide clear evidence of the relationship between strain and intermixing.