Nucleation of cobalt silicide islands on Si(111)-7 × 7

Abstract

We present a scanning tunnelling microscopy (STM) investigation of Co silicide cluster and island formation on Si(111)-(7 × 7). We identify sub-nanometre clusters, which we propose to be the precursors to Co silicide nucleation and growth. The observation of metastable phases and various domains on the surface suggest significant Si rearrangement during silicide formation. Surface diffusion of both Si and type-1 clusters plays a vital role in the nucleation of Co silicide islands. With the help of density functional theory calculations, we propose a model for the surface structure of atomically flat CoSi2(111)-(2 × 2) islands. © 2006 IOP Publishing Ltd.