Nonlinear evolution of a morphological instability in a strained epitaxial film

TL;DR

This paper investigates the nonlinear morphological instability in strained epitaxial films, deriving and numerically solving dynamical equations to reveal island formation, coarsening behavior, and dimension-dependent effects.

Contribution

It introduces nonlinear, nonlocal dynamical equations for strained epitaxial films with wetting interactions and analyzes their solutions in multiple dimensions.

Findings

Surface evolves into islands separated by wetting layers above critical thickness.

Island chemical potential decreases with volume, driving coarsening.

Coarsening follows power laws with clear dimension dependence.

Abstract

A strained epitaxial film deposited on a deformable substrate undergoes a morphological instability relaxing the elastic energy by surface diffusion. The nonlinear and nonlocal dynamical equations of such films with wetting interactions are derived and solved numerically in two and three dimensions. Above some critical thickness, the surface evolves towards an array of islands separated by a wetting layer. The island chemical potential decreases with its volume, so that the system experiences a non-interrupted coarsening described by power laws with a marked dimension dependence.