Uniformity Analysis of Metallization-Induced Recombination Losses by Photoluminescence Imaging

We present an approach for the determination of the locally averaged recombination parameter j0,met assigned to the metal contacts of a solar cell. A set of samples with test fields combined with an interpolation scheme allows the precise prediction of expected local photoluminescence imaging (PLi) intensities for virtually non-metallized sample areas with a standard deviation of 0.7%. The ratio of the actually measured PLi signal in a metallized test field with respect to the predicted signal of the virtually non-metallized test field then serves as an input for numerical simulations for the extraction of j0,met. We find a clear correlation of the locally determined j0,met with both, the local peak firing temperature measured in-situ by a thermal imaging system installed in the firing furnace and the local sheet resistance of the diffused n+-region. These results demonstrate the high capability and accuracy of our approach for the uniformity characterization of metallization-induced recombination losses.