Equilibrium shapes and properties of epitaxially strained islands

We calculate the equilibrium morphology of an epitaxial strained layer which wets the substrate (Stranski-Krastanow growth), in a two-dimensional continuum model. The layer coalesces into a single discrete island, with zero contact angle to the film wetting the substrate. Small islands have a minimum width, and hence an arbitrarily small aspect ratio. Very large coherent islands have a shape that approaches a ball sitting atop the wetting layer.