A review was presented of phosphorus emitter diffusion and gettering, as it pertained to multicrystalline silicon solar-cell processing. A brief summary was given of the diffusion properties of phosphorus in silicon; explaining the nature of the characteristic kink-and-tail profiles often encountered in the solar cells. Attention was paid to phosphorus diffusion gettering, with particular regard to the inhomogeneous nature of multicrystalline silicon. It was noted that the abundant presence of dislocations in areas of material having a low recombination lifetime could cause only minor lifetime enhancements in such areas upon phosphorus diffusion. Taken together with the dissociation of precipitated impurities, in combination with longer effective diffusion lengths of the impurities, it could be seen that even poor areas of multicrystalline material could exhibit a noticeable improvement upon phosphorus diffusion gettering after applying a lower diffusion temperature for a longer period.

Overview of Phosphorus Diffusion and Gettering in Multicrystalline Silicon. A.Bentzen, A.Holt: Materials Science and Engineering B, 2009, 159-160, 228-34