Photoemission Study of the CoSi sub 2 (111)-Si Surface.

Epitaxial CoSi sub 2 terminated with a thin Si bilayer has been studied by synchrotron radiation photoemission. This well-defined surface phase of CoSi sub 2 is obtained by high temperature annealing in the range 450-650C. The samples used were prepared by MBE techniques with a film thickness of ~ 800angstroms on Si(111) substrates capped with a ~ 100angstroms film of a-Si to act as an oxide barrier while samples were transformed 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 ~450-650C for one minute. Photoemission spectra were taken with total resolution in the range 200-237 meV and show evidence for four spin-orbit doublets.