Electronic structure of the Si(001) c (6 x 2)-Ag surface studied by angle-resolved photoelectron spectroscopy using synchrotron radiation

The surface electronic structure of the single-domain Si(001)c(6 x 2)-Ag su rface has been studied by polarization-dependent angle-resolved photoelectr on spectroscopy (ARPES) using synchrotron radiation. Through detailed ARPES measurements, the Si(001)c(6 x 2)-Ag surface is found to be semiconducting with a band gap larger than similar to 0.7 eV. Three different surface sta tes are identified within the bulk band gap, whose dispersions and symmetry properties are determined. The surface band structures observed have a clo se resemblance with those of the Si(001)(2 x 3)-Ag surface reported recentl y [H. W. Yeom et al., Phys. Rev. B 57, 3949 (1998)]. This result suggests a similarity between the substrate reconstructions of the c(6 x 2)-Ag and (2 x 3)-Ag phases formed at a proximate condition. The surface structure of S i(001)c(6 x 2)-Ag and the origins of the surface states observed are discus sed.