Possibilities of applying geometric optics for calculations of nano- and microstructures in photovoltaic devices

The optical characteristics used in the photovoltaics of nano- and microstructure, evaluated using electromagnetic radiation transfer computation software, mismatch with data obtained at high estimated times. The ability to apply the geometric optics approximations is shown for this purpose. Relevant computations using a 3D ROKS-RG programming tool (the Monte Carlo method) are performed for various experimental results on the optical parameters of nano- and microstructures available in the scientific literature. Given that surface roughness exists as a byproduct of etching during the preparation of structures, the theory is found to satisfactorily agree with experiment. Moreover, most of the radiation is absorbed on account of the surface roughness of substrates, which is expected to induce a nonuniform charge carrier distribution over the structure height and may be among the reasons for the insufficiently high efficiency of solar elements with radial $p$–$n$ geometry.