While a variety of methods have been developed to carry out atomistic simulations of thinfilm growth at small deposition angles with respect to the substrate normal, due to the complex morphology as well as the existence of multiple scattering of depositing atoms by the growing thin-film, realistically modeling the deposition process for large deposition angles can be quite challenging. Accordingly, we have developed a computationally efficient method based on the use of a single graphical processing unit (GPU) to carry out molecular dynamics (MD) simulations of the deposition and growth of thin-films via glancing angle deposition. Using this method we have carried out large-scale MD simulations, based on an embedded-atom-method potential, of Cu/Cu(100) growth up to 20 monolayers (ML) for deposition angles ranging from 50 • to 85 • and for both random and fixed azimuthal angles. A variety of quantities including the porosity, roughness, lateral correlation length, average grain size, strain, and defect concentration are used to characterize the thin-film morphology. For large deposition angles (θ ≥ 80 o) we find well-defined columnar growth while for smaller angles, columnar growth has not yet set in. In addition, for θ = 70 o − 85 o the thinfilm porosity and columnar tilt angles (for fixed azimuthal angle φ) are in reasonable agreement with experiments. We also find that for both random and fixed φ the average strain is initially compressive but becomes tensile after the onset of columnar growth, in good qualitative agreement with recent experimental observations. Our results also indicate that for large deposition angles a variety of complex dynamical processes including coalescence, large-scale collective events, and budding play a key role in determining the evolution of the surface morphology and microstructure.

A self-consistent rate-equation (RE) approach to irreversible island growth and nucleation is presented which takes into account cluster mobility. As a first application, we consider the irreversible growth of compact islands on a two-dimensional surface in the presence of monomer deposition (with rate F) and monomer diffusion (with rate D(1)) while the mobility of an island of size s is assumed to satisfy D(s)=D(1)s(-μ) where μ>0. Results are obtained for the dependence of the island-density and island-size distribution (ISD) on the parameters D(1)/F, μ, and coverage θ. For all values of μ, we find excellent agreement between our self-consistent RE results and simulation results for the island and monomer densities, up to and even somewhat beyond the coverage corresponding to the peak island density. We also find good agreement between our self-consistent RE and simulation results for the portion of the ISD corresponding to island sizes less than the average island-size S. However, for larger island sizes the effects of correlations become important and as a result the agreement is not as good. Using our self-consistent RE approach we also demonstrate that the discrepancies between simulations and recent mean-field predictions for the exponent τ(μ) describing the power-law size dependence of the ISD for μ<1 can be explained almost entirely by geometric effects. Our results are also compared with those obtained using a simpler mean-field Smoluchowski approach. In general, we find that, except for the case μ=1/2 (for which the island and monomer densities are reasonably well predicted), such an approach leads to results which are in poor agreement with the simulations.

The critical island-size, stability, and morphology of 2D colloidal Au nanoparticle islands formed during drop-drying are studied using an empirical potential which takes into account core-core, ligand-ligand, and ligand-solvent interactions. Good agreement with experiment is obtained for the dependence of the critical island-size on nanoparticle diameter. Our results for the critical length-scale for smoothing via edge-diffusion are also consistent with the limited facet size and island-relaxation observed in experiments. In addition, the relatively high rate of monomer diffusion on an island as well as the low barrier for interlayer diffusion are consistent with experimental observations that second-layer growth does not occur until after the first layer is complete.

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We consider the thermomechanical properties of highly defected, tilted copper nanocolumns grown via simulations of glancing angle deposition. The large defect density and compressive strain lead to ultra-low activation energies for plastic deformation via collective shear motion. As a result, the thermal oscillation amplitude is independent of temperature. This leads to a mechanism for large-amplitude thermally induced nanocolumn oscillation, in which the dynamics corresponds to a sequence of correlated activated events. V