The surface electronic structure of epitaxial &3 X &38.30 ErSi& 7 layers on Si(111)has been studied by high-resolution angle-resolved ultraviolet photoemission spectroscopy. Typical surface states or resonances are unambiguously identified and their band dispersions mapped along the high-symmetry I M, I I(, and E M lines of the (1 X 1) surface Brillouin zone. These data are compared to the band structure of two-dimensional p (1 X 1) Er silicide extensively studied in previous works. It is found that the prominent surface bands observed in the 0 -3-eV binding-energy range can be readily derived from the p(1X 1) surface-silicide bands folded back into the reduced &3 X &3 zone. This indicates that the bulk silicide is also terminated with a buckled Si layer without vacancies, quite similar to the surface-silicide termination. In particular, specific surface bands reflect the doubly (essentially) occupied dangling bonds and the back bonds of the buckled Si top layer.

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