Seminars Archive

The atomistics of ironsilicide formation on Si(111) studied with high temperature STM

Abstract
Elementary steps of the nucleation of ironsilicide on Si(111)-7x7 during gas phase (CVD) and molecular beam (MBE) deposition were investigated by high temperature STM directly during growth up to 600 C. Above 300 C STM-"movies" show the formation of ordered silicides when solely iron is deposited and silicon from the substrate reacts to form the silicide. Even in the very first stage three different types of islands nucleate which can be identified by their surface reconstruction and their step height. The dominating type (gamma-ironsilicide) is surrounded by holes in the silicon substrate, a second type is implanted in the surface, the third type can be identified as consisting of three domains of alpha-ironsilicide. For the first island type a quantitative analysis yields the exact composition of the silicide nuclei as a function of temperature. Only small differences between CVD using ironpentacarbonyle and MBE experiments were found. Co-deposition of Fe and Si (using disilane) was used to determine the conditions for stochiometric deposition