The low energy ion assisted control of interfacial structure: Ion incident energy effects

Abstract

The properties of multilayered materials are often dependent upon their interfacial structure. For low temperature deposition processes where the structure is kinetically controlled, the interfacial roughness and the extent of interlayer mixing are primarily controlled by the adatom energy used in the deposition. Inert gas ion assistance during the growth process also enables manipulation of the interfacial roughness and intermixing. To explore inert gas ion assistance, a molecular dynamics approach has been used to investigate the role of ion energy and ion species upon the flattening of various surfaces formed during the growth of the Ni/Cu/Ni multilayers. The results indicated that ion energies in the 1–4 eV range could flatten the “rough” copper islands on either copper or nickel crystals. To flatten the rough nickel islands on copper or nickel crystals, higher ion energies in the 9–15 eV range would have to be used. Significant mixing between nickel island atoms and the underlying copper crystal atoms started to occur as the ion energy was increased to around 6–9 eV. However, little mixing was observed between the copper island atoms and the underlying nickel crystal atoms in the same ion energy range. At a given ion energy, the heavier (xenon) ions were found to produce more surface flattening and mixing than the lighter (argon) ions.

Low-energy ion-assisted control of interfacial structures in metallic multilayers

“…The predicted misfit dislocation structures are also similar to those observed by high-resolution transmission electron microscopy [31,32]. Recent simulations of ion interactions with a model Co-on-Cu bilayer system indicate that low (5-10 eV) energy impacts can be highly effective at flattening small (10 atoms) cobalt clusters on (1 1 1) copper surfaces without inducing interfacial alloying [24,33,34]. They also reveal that appropriate combinations of ion species (mass), ion energy, ion fluence, and ion incident angle can be used to selectively activate either atom recoil, atomic exchange, or direct jumping mechanisms to flatten surface asperities [24,33].…”

Phase stability and in situ growth stresses in Ti/Nb thin films

“…Molecular dynamics (MD) simulations, which have been shown to be a powerful tool in investigating thin film growth [30][31][32][33], were performed by utilizing the LAMMPS code [34] with the Ti-Nb binary embedded atom model potential found in Ref. [35].…”

Molecular Dynamics Simulation of Thin Film Growth with Energetic Atoms

“…For single Ag impacts on a clean Cu surface, they determined exchange probabilities of 0.014 at 3 eV, 0.047 at 5 eV, 0.258 at 7 eV, and 0.396 at 9 eV for deposition at normal incidence. Zhou and Wadley have published a series of papers examining effects of hyperthermal atoms [36][37][38] and inert gas ions [39] on surface and interface t=31.5 1)5 t=32.0 pl' Figure 7. Percolation mixing of a 10 eV silver atom (white) released at 30.5 ps, substrate atoms are dark gray, film atoms are medium gray, and the ejected atom is marked with a dark zero [25].…”