Extracting Metal Contact Recombination Parameters From Effective Lifetime Data

The surface recombination at metallized surfaces of a solar cell is of significant interest for cell process development, considering the limiting effect such recombination has on cell efficiency. This recombination is difficult to measure accurately, because the enhanced recombination at the metal contacts causes an inhomogeneous minority carrier profile, which limits the viability of conventional photoconductance-based recombination measurements. In this study, a photoluminescence-based system is used to measure the injection-dependent effective lifetime of full area metallized samples. Several techniques to extract surface recombination parameters from these data are compared. A simulation-based approach is shown to be superior to the simplified analyses that are more commonly applied to data of this type, in the case where the depth profile of the minority carrier density is nonuniform.