It was recalled that, in epitaxial Si films which were grown from In solution, it was common to observe a low-energy geometry of the grain boundaries. Most of the grain boundaries grew approximately perpendicularly to the substrate surface. The epitaxial layer assumed a columnar grain structure which, especially in the case of a fine-grained substrate, minimized the effect of grain boundaries upon minority carrier recombination. Thin films, which had been solution-grown onto cast wafers, were here used as an example of the liquid-phase epitaxy of Si on a polycrystalline seed. The structural and electrical properties of grain boundaries in the epilayers were investigated by means of transmission electron microscopy and electron beam-induced current measurements. It was found that layers which had been grown under conditions that were close to thermodynamic equilibrium led to a low electrical activity of the defects and to a low-energy geometry of the grain boundaries. Layers which were grown at various rates exhibited no difference in electrical activity. Trenches at grain boundary sites were typical surface features of the epilayers. Increasing the growth rate reduced the trench depth.

A.Voigt, B.Steiner, W.Dorsch, J.Krinke, M.Albrecht, H.P.Strunk, G.Wagner: Journal of Crystal Growth, 1996, 166, 694-9