Extraction of Recombination Properties from Lifetime Data

Extraction of recombination properties like the recombination pre-factor J0 and the Shockley-Read-Hall base lifetime from photoconductance data on test structures and half-fabricates of photovoltaic cells is not always straightforward and unambiguous. In this paper the well-known “slope method” of Kane and Swanson will be compared to the method offered by the Quokka code. The Quokka code numerically solves the distribution of the excess carrier concentration over the thickness of the wafer at several injection levels. In this way artefacts due to transport limitations are avoided and the analysis does not rely on data at a single injection level. This gives more reliable results for J0 and the base lifetime. A method to the determine the base lifetime from the implied VOC at 1 Sun illumination values is also presented.