Ray tracing vs. electromagnetic methods in the analysis of antireflective textured surfaces [of solar cells]

The radiation scattering in textured solar cell surfaces is usually analyzed by means of a ray optics approach. In this work, the authors investigate the validity of this technique for the particular case of a periodic grating of triangular profile. The problem is solved using a rigorous method from electromagnetism, the modal multilayer and the reflected radiation and its deviation from the ray optics approach is obtained. A perfect conducting medium is considered. The propagating modes show deviations from the ray optics approach, even for wavelength-period ratios (λ/d) of the order of 0.1. Since values of λ/d examined are of interest in photovoltaics, the authors conclude that EM effects must be taken into account in order to obtain accurate estimations of the radiation effectively absorbed in semiconductor textured surfaces