Inferring dislocation recombination strength in multicrystalline silicon via etch pit geometry analysis

Dislocations limit solar cell performance by decreasing minority carrier diffusion length, leading to inefficient charge collection at the device contacts. However, studies have shown that the recombination strength of dislocation clusters within millimeters away from each other can vary by orders of magnitude. In this contribution, we present correlations between dislocation microstructure and recombination activity levels which span close to two orders of magnitude. We discuss a general trend observed: higher dislocation recombination activity appears to be correlated with a higher degree of impurity decoration, and a higher degree of disorder in the spatial distribution of etch pits. We present an approach to quantify the degree of disorder of dislocation clusters. Based on our observations, we hypothesize that the recombination activity of different dislocation clusters can be predicted by visual inspection of the etch pit distribution and geometry.