Electronic structure of the prototypical As:Si(111)-1x1 surface investigated by inverse photoemission spectroscopy

Angle-resolved inverse-photoemission spectra have been measured on the nonreconstructed As:Si(111)-1×1 surface along the two main directions Γ¯K¯ and Γ¯M¯ of the surface Brillouin zone. We observed three empty bands, the lower one of which is characteristic of a surface state partly resonant with bulk states in good agreement with theoretical calculations. We also observed a marked asymmetry in the dispersion along the M¯’Γ¯M¯ direction.