XPS study of nanostructured surface-Co on Si(100)

Abstract

Different coverage of Cobalt from ~0.5ML to ~10ML were deposited on clean Si(100) and H-terminated Si(100) surfaces at room temperature. A strong thickness dependence of the correlation-induced satellite signal in Co 2p photoemission spectra was observed. It was found that relative photoemission intensities of the satellite to Co 2p peak increase when the Co film [on Si(100)] thickness increases. After the Co film was annealed up to 450oC, the satellite disappears. The results can be explained from the intermixing influence of d-d electronic interaction and Si 3p-Co 3d bonding on such reduced-dimension systems. On the other hand, the evolution of ultra-thin Co films on clean and H-terminated Si(100) surfaces upon annealing temperature in the range from room temperature to 650oC was studied by means of core-level and valence-band in-situ X-Ray Photoemission Spectroscopy (XPS). ~2ML to ~8ML Co was deposited onto Si surface at room temperature and then annealed. The behavior of the Co-Si interfaces upon the annealing temperature was examined using Co 2p core level shifts and valence band measurements. By comparing the experimental with theoretical CoSi2 and CoSi band structure, together with the investigation of core level shift, the formation of CoSi2 and CoSi is confirmed.