Polarization-dependent reflectivity of Si(111)-(2×1) surface above the gap

Results of surface differential reflectivity with polarized light at photon energies above the gap are presented for Si(111)-(2×{}1) single-domain surfaces. They show an anisotropic behavior in the 2--3.5-eV range with a maximum when the electric vector is parallel to the [2{}11] direction of the reconstructed surface. The results are compared with those previously reported for energies below the gap and are interpreted in terms of transitions involving dangling-bond bands at different points of the surface Brillouin zone, in the framework of the Pandey model of the surface.