Elastic effects and phase segregation during the growth of thin alloy layers by molecular-beam epitaxy

We explore the effects of stress and strain on the composition modulations seen during the growth of thin solid films by molecular-beam epitaxy when phase separation is the driving mechanism for the concentration inhomogeneity. A top view of the growing thin film shows lamellar and hexagonal patterns of phase-separated domains, the elastic effects being directly responsible for the appearance of the hexagonal order. We find that in the lamellar regime, elastically deformed lamellae are separated by undeformed interfaces, while in the droplet phase, the soft component is deformed and wraps the hard component. We also discuss the effects of crystal anisotropy in our system.