Mechanisms of metal self-ordering at grazing PVD on ion-erosion-induced surface pattern

By grazing metal vapor deposition perpendicular to ripples of pre-patterned, oxidized Si surfaces, a chain-like formation of the metal nanoclusters along the ripples have been observed. The structures are located on the slopes which point towards the evaporation source. The self-ordering of metal nanostructure has been observed neither for normal deposition nor for low-angle deposition parallel to the ripple direction. The features of the metal nanostructure depend strongly on the evaporation angle.
In this work, we studied the process of silver deposition on pre-patterned, oxidized Si surfaces by means of 3D lattice kinetic Monte Carlo simulations. The experimentally observed Ag nanostructures could be reproduced. It was shown that the extremely low sticking probability of deposited Ag together with a slope-dependent deposition rate leads to a strongly selective Ag nanocluster nucleation on the surface because
the nucleation rate depends on the square of the adatom concentration.