Dynamics of pit filling in heteroepitaxy via phase-field simulations

Heteroepitaxial growth on a pit-patterned substrate is investigated by phase-field simulations, tackling both film and substrate geometry and elastic properties. The dynamics results from material deposition and redistribution via surface diffusion according to the tendency toward free-energy minimization. The balance between surface energy, misfit strain, and wetting effects is taken into account. Numerical solution by finite-element method permits to properly account for the role played by the actual pit morphology in determining strain relaxation. The mechanisms leading to island growth into the pit are discussed. Different growth parameters and pattern geometries are considered and their effects on island ordering are explained and related to experimental evidences in literature.