Atomistic and coarse-grained modeling of epitaxial thin film growth and relaxation

Thin film deposition provides a pathway to create a variety of functional surface nanostructures. However, once created such nanostructures must be stable in order to be useful. This talk gives an overview of issues, strategies, and successes in modeling of epitaxial thin film growth (nanostructure formation) [1] and relaxation (nanostructure stability) [2] on atomically flat single-crystal substrates.

In the submonolayer regime, deposited atoms diffuse across the substrate and aggregate into 2D (single-atom high) islands. What are the characteristics of this island distribution? Subsequent to deposition, the distribution coarsens. What are the mechanisms? In the multilayer regime, a growth instability often appears resulting in rough films sometimes displaying 3D mounds with selected slopes. Is there a PDE to describe evolution of film height? A unresolved problem is characterization of the post-deposition smoothing of these rough films.

Modeling strategies include: atomistic lattice-gas modeling & KMC simulation, step-dynamics modeling, and continuum PDE derivation and analysis.

[1] Evans et al., Surface Science Reports, 61 (2006) 1-128.

[2] Thiel et al., J.Phys.Chem.C 113 (2009) 5047; Science 330 (2010) 559.