Computational Investigation of the Effect of Cluster Impact Energy on the Microstructure of Films Grown by Cluster Deposition

Abstract

The microstructure of thin film growth during low-energy cluster beam deposition is studied in a series of molecular dynamics simulations. The films are grown by depositing Ni clusters on a Ni (111) substrate at room temperature. The deposition of a single Ni cluster is first studied, followed by a detailed analysis of the effect of the impact velocity of the deposited clusters on the microstructure of the growing film. The observed differences in the microstructure are related to the differences in the impact-induced processes. In the case of the lower incident energy only a partial transient melting of a small contact region between the incoming cluster and the film takes place. Epitaxial growth is seen to occur for the first few layers of the clusters in contact with the substrate, above which the clusters largely retain their crystal structure and orientation. The films grown by deposition of low-energy clusters have a low density (~50% of the density of a perfect crystal) and a porous "foamy" structure with a large number of interconnected voids. The higher-energy impacts lead to the complete melting and recrystallization of the whole cluster and a large region of the film, leading to the epitaxial growth, smaller number of localized voids, and a higher overall density of the growing film.

Ordering effects in disordered systems: the Au–Si system

“…However, with this potential we did not manage to reproduce correctly the basic properties of the liquid state. The second one [24] is based on a rather empirical approach combining the embedded-atom model (EAM) [25] and the Stillinger-Weber (SW) potential [26]. We did not retain this potential either since the three-body term is known to overemphasize the directional covalent bonding in liquid Si [27].…”