Epitaxy in solid-phase thin film reactions: Nucleation-controlled growth of iron silicide nanostructures on Si(001)

Abstract

A special type of epitaxial growth appears during solid phase thin film reactions, where the reaction product grows epitaxially on the substrate. Some metal silicide layers and nanostructures are known to develop such epitaxial structures. In this study iron silicide was used to study the effect of the growth mode on the epitaxial growth. Strain-induced, self-assembled iron silicide nanostructures were grown on Si(001) substrates by electron gun evaporation of 1.0 nm iron and subsequent annealing at 500-850°C for 60 minutes. The growth processes were checked by reflection high energy electron diffraction, and the formed structures were characterized by scanning electron microscopy and optical microscopy. The iron silicide nanostructures were oriented in square directions epitaxially fitting to the surface of Si(001). The shape and size of the nanostructures depended on the annealing temperature. In some cases the nanoparticles were arranged in circles. This might be the direct consequence of a nucleation controlled type transition of iron monosilicide to iron disilicide phase at nanoscale.