STM studies of PtSi formation on Si(111) by solid state epitaxy

Formation process and surface structure of platinum silicide thin layers have been studied using scanning tunneling microscopy. The investigated structures have been grown by solid state epitaxy upon deposition of 5 and 10 monolayers (ML) of platinum on the Si(111) surface and annealing at temperatures between 250°C and 1100°C. Platinum silicide exhibits a tendency to form islands as the annealing temperature increases. At a coverage of 5 ML the platinum silicide grows epitaxially with the relation of PtSi(010) Si(111). In contrast, for 10 ML coverage the PtSi(100) Si(111) growth was found. New types of surface reconstruction were observed on the both surfaces. Models successfully explaining investigated reconstructions are proposed. The electronic structure of platinum silicide in the vicinity of the Fermi level has been deduced from the scanning tunneling spectroscopy measurements.