Single and double side textured black silicon require different annealing conditions for optimal passivation with ALD Al₂O₃

Black silicon is an attractive surface for solar cells thanks to its intrinsic antireflective properties, however progress in surface passivation is required to exploit its full potential. Here, we present effective minority carrier lifetime measurements on single side textured, double side textured, and flat reference Si surfaces, passivated by Al₂O₃ with subsequent thermal activation. Effective lifetime measurements revealed that the annealing time resulting in highest effective lifetime, and therefore in the lowest surface recombination velocity of the textured surface, is depending on whether the wafers are single or double side textured. It follows that optimization of passivation of black silicon lifetime samples needs to be carried out on samples with texturing on one or both sides, depending on the solar cell architecture of interest.