First-principles calculations of steering forces in epitaxial growth

Abstract

Although atoms deposited during epitaxial growth strongly prefer to bind to step bottoms of existing islands, the geometrical proximity of step tops can lead to atoms landing there instead, significantly altering film morphology and contributing to growth instabilities. To shed light on such steering effects, we have mapped out the three-dimensional static potential-energy surface (PES) for Cu atoms approaching a stepped Cu(100) surface using density-functional theory (DFT). Depending on the kinetic energy of incident atoms, surface relaxations may be too sluggish, and we have therefore computed the PES both with and without allowing substrate relaxations. While a comparison with the corresponding embedded-atom-method (EAM) results indicates relatively good agreement, the DFT calculations suggest that the steering effect is slightly weaker than predicted by EAM calculations. These results also support a previous comparison with experiment, which indicated that the overall funneling probability for deposition at a [110] step edge on the Cu(100) surface is close to but slightly lower than that predicted via EAM simulations.