Ion current distribution on a substrate during nanostructure formation

The distribution of an ion current density on a substrate with a discontinuous film consisting of islands of dimension 25–100 nm was studied numerically. It was found that the ion current distribution is highly non-uniform and islands of the discontinuous film are enclosed with sharply defined zones where the current density is very low. The total area of low current zones reaches 30–50% of the substrate area, depending on the voltage applied to the substrate. The ratio of island radius–low current zone width depends on the island size and equals approximately 1.0 for large islands and 0.5 for small islands. It is shown that the island distribution function may be controlled by bias voltage variation.