Tuning reactive epitaxy of silicides with surface steps: Silicide quantum dot arrays on Si(111)

Abstract

We have studied the nucleation and growth of cobalt silicides on vicinal silicon surfaces. The latter exhibit one-dimensional arrays of steps with narrow terrace widths ranging from 20 Å to 40 Å (miscut angle between 9 ∘ and 4.6 ∘, respectively). Submonolayer amounts of Co were deposited by thermal evaporation on such vicinal Si(111) surfaces by reactive thermal deposition, and the resulting silicide structures were analysed by scanning tunnelling microscopy. The presence of narrow terraces in the system notably alters the usual nucleation process of cobalt silicide on flat Si(111). It is observed that by varying the Co coverage and vicinal angle, the size and amount of the hexagonal silicide clusters can be controlled producing a dense array of quantum dots. This behaviour contrasts to that observed on flat substrates, where nanocluster structures are notably scarce.