Photoemission study of the CoSi2(111)–Si surface

Abstract

Epitaxial CoSi2 terminated with a thin Si bilayer has been studied by synchrotron radiation photoemission. This well‐defined surface phase of CoSi2 is obtained by high‐temperature annealing in the range 450–650 °C. The samples used were prepared by molecular‐beam epitaxy techniques with a film thickness of ∼800 A on Si(111) substrates and capped with a ∼100 A film of a‐Si to act as an oxide barrier while samples were transferred to the photoemission chamber. The surfaces studied by photoemission were prepared by careful sputtering to remove the oxide and a‐Si layer and then anealed to ∼450–650 °C for 1 min. Photoemission spectra were taken with total resolution in the range 200–237 meV and show evidence for four spin–orbit doublets. Our samples and results are somewhat different from those of previous studies of thin CoSi2 films or studies of bulk CoSi2 samples. We find three surface Si(2p) components: one shifted to higher binding energy and two shifted below the main Si(2p) spin‐orbit doublet in CoSi2. ...