Quantification of iron redistribution between acceptors in co-doped Silicon

Low-cost Silicon feedstock with multiple native dopants (mostly Boron and Phosphorous but also Gallium and trace amounts of Aluminum) is establishing itself as a cost effective complement to incumbent ultra high purity Silicon. In such co-doped materials, interstitial iron has recently been shown to redistribute from one acceptor type to the other. In this paper, the redistribution of this important defect in solar cells is shown to be primarily activated through carrier injection under illumination. A characteristic signature of the iron in the lifetime spectrum - the cross-over point - is used as an independent and quantitative confirmation for the redistribution of the iron.