Optical absorption enhancement in nano/micro textured thin film solar cells

The new theoretical approach for calculations of monochromatic light transmission through a thin absorbing film with one or two slightly rough interfaces has been elaborated. The theoretical calculations were based on electro-dynamical equations for normal incidence of light, where the roughness was considered as perturbation to dielectric permittivity and assumed to be statistically homogeneous and described by Gaussian correlation function. The spectra of the transmittance of thin metal (Au, Ag, Al) continuous films with rough or flat interfaces with air and semiconductor GaAs at normal incidence of light have been calculated. Both numerical and analytical considerations demonstrate an increase of transmission coefficient by about ten percent and agree with experimental data, obtained on solar cells with nearly flat (nano-textured) and microtextured by anisotropic etching GaAs surface.