Generalized analytical model for the calculation of light transmittance through a thin conducting film

The influence of nano-scale roughness on the transmittance of three-layer structures with a homogeneous permittivity value in each layer has been analyzed. Using the Green's functions formalism, we determined the transmittance in the first order of the perturbation theory. For example, the spectral dependencies of the light transmission through a thin metal (Au, Ag, Al) continuous film deposited onto GaAs substrate were calculated for the cases of roughness inherent to “air-metal”, “metal-semiconductor” or both surfaces. The angle and polarization dependencies of the light transmission have been calculated, too. These calculations demonstrated a transmittance increase at the inclined incidence for the p-polarized wave, which can be explained by excitation of surface polaritons. The increase of the transmittance caused by the nano-roughness reaches about 10% compared to that in the case of flat surface. This value is in agreement with the experimental data for nearly smooth rough surfaces.