Effect of the lattice misfit on the equilibrium shape of strained islands in Volmer-Weber growth

TL;DR

This study investigates how lattice misfit influences the equilibrium shape of strained pyramidal islands in Volmer-Weber growth, revealing differences between tensile and compressed islands and their strain relaxation behaviors.

Contribution

It provides a detailed analysis of the impact of lattice misfit on island shape and strain distribution, aligning theoretical predictions with experimental observations.

Findings

Tensile islands have smaller aspect ratios than compressed islands.

Strain decreases faster with thickness in compressed islands.

Upper layers become unstrained at a certain height, preventing full pyramid formation.

Abstract

We have studied the effect of the misfit on the equilibrium shape of three-dimensional pyramidal islands grown on a foreign substrate in the case of incomplete wetting (Volmer-Weber mode of growth). We have found that tensile islands have smaller aspect ratios compared with compressed islands owing to its better adhesion to the substrate. The average strains of consecutive layers decrease faster with thickness in compressed than in tensile islands. The strains decrease rapidly with thickness, with the consequence that above a certain height, the upper layers of the pyramid become practically unstrained and does not contribute to a further reduction in the upper base. As a result, the truncated pyramids are not expected to transform into full pyramids. Our results are in good agreement with experimental observations in different systems.