Effect of thickness and surface treatment on silicon water reflectance

In this paper we present reflectance measurements on silicon wafers and the dependence of the reflectance on the thickness, on the texturization and on the back metallization. Silver and aluminium have been deposited using screen printing and also vacuum evaporation as a reference. The work was intended as a contribution to the problem of light trapping that becomes important for thin wafers for commercial, low cost, silicon cells. For the case of wafers with polished surfaces, the results are analysed to yield the reflectivity of the back surface and the total energy absorbed in the sample. Texturization, on the contrary, introduces diffraction phenomena making the evaluation of the absorbed energy more complex.