INTERACTION OF EXCITONS WITH A GENERALIZED MORSE SURFACE-POTENTIAL - P-POLARIZATION GEOMETRY OF THE INCIDENT LIGHT AT A SEMICONDUCTOR SURFACE

We investigate theoretically the optical response of excitons localize d near the surface of a semiconductor. Spectra of reflection of p-pola rized light from strongly treated semiconductor surfaces are calculate d by using a generalized Morse surface potential. The spectra exhibit prominent dips produced by the generation of exciton bound stares and their corresponding longitudinal polariton modes. The position and the form of spectral dips depend not only on potential-well parameters bu t also on the value of the longitudinal-transverse splitting and the s urface damping. Our results are compared with experimental spectra for CdSe and we also calculate reflectivity spectra for GaAs.