DETERMINATION OF THE COMPLEX DIELECTRIC FUNCTION OF CDTE(110)1X1 SURFACE BY POLARIZED SURFACE DIFFERENTIAL REFLECTIVITY

We present a determination of the complex surface dielectric function (SDF) of the CdTe(110)1 x 1 surface obtained by using polarized surface differential reflectivity data (Delta R/R) obtained for the light electric vector along the [1 $($) over bar$$ 10] and [001] directions, i.e. ''parallel'' and ''perpendicular'' to the natural chains of the unreconstructed (110) surface. In the energy range below 3.3 eV the imaginary part of the SDF (epsilon'') and Delta R/R are very similar while above 3.3 eV they differ markedly because of the effect of bulk contribution. Three mainly isotropic structures are clearly visible in the epsilon'' spectra at the following photon energies: 2.7, 3.3 and 3.65 eV. The interpretation of such structures in terms of optical transitions between surface state bands as derived from direct and inverse photoemission is shown. Moreover, the effective number of electrons per atom participating in the optical transitions is calculated for energies up to 4.0 eV.