Nanostructures in thin-film epitaxy: Exploring and exploiting substrate-mediated interactions

We review recent advances made in understanding the ramifications of substrate-mediated interactions for thin-film growth. Experimental studies and first-principles calculations with density-functional theory (DFT) indicate that substrate-mediated interactions can significantly influence thin-film growth. We review the findings from our kinetic Monte Carlo simulations used to model the growth of thin films, both with and without substrate-mediated interactions. For Ag heteroepitaxy on Pt(111), the pair interaction energies and adsorbate diffusion barriers were obtained from DFT calculations. Island densities for this system show significant deviations from what is predicted by classical nucleation theory. The electronic interactions created by the adsorbed atoms lead to the formation of repulsive barriers surrounding small islands and, as a result, sharp island-size distributions are produced. The island-size distributions can be manipulated by changing the growth conditions to yield desirable island sizes and shapes.