Experimental results on the effect of the Ge doping on the distribution of dislocations in directional solidified multi-crystalline Si were presented. The dislocation density distribution was analyzed on the basis of the average dislocation density and the cumulative probability by means of etch pits counting via optical auto-focus microscope and the photovoltaic scan method. The Ge doped ingots showed a significantly lower average dislocation density and dislocations were more homogeneously distributed in the Si matrix, whereas the undoped ingot contained large areas of accumulated dislocations. Apparently, the overall dislocation density was reduced by the induced strain field and the lower mobility of dislocations due to the pinning effect.

The Impact of Germanium Doping on the Dislocation Distribution in Directional Solidified mc-Silicon. M.P.Bellmann, T.Kaden, D.Kressner-Kiel, J.Friedl, H.J.Möller, L.Arnberg: Journal of Crystal Growth, 2011, 325[1], 1-4