Surface-induced optical anisotropy of the (001) and (113) silicon surfaces

The surface-induced optical anisotropy of clean and hydrogenated (001) and (113) surfaces of silicon has been calculated. The equilibrium atomic configurations of the surface atomic structures were determined from fully converged self-consistent total-energy calculations within the local density approximation. The optical functions of the silicon surfaces have been obtained beyond the density-functional theory with ab initio pseudopotentials and by the semiempirical tight-binding method. The reflectance anisotropy (RA) spectroscopy signal of the clean (001) and (113) surfaces in the region around 3.0 eV originates from surface to bulk optical transitions. On the hydrogenated (113) silicon surface a strong surface induced RA response is obtained in the region of the $E_1$ and $E_2$ bulk critical points, where the line shape corresponds to the first derivative of the bulk dielectric function. The calculated RA spectrum of the hydrogenated (113) silicon surface in the regions of the $E_1$ and $E_2$ structures is more intense in relation to the (001) surface. These results will be discussed in comparison with experimental data.