Based on known theories of twinning in semiconductor crystal growth, a new model was proposed to study the occurrence of twins during the solidification of photovoltaic multicrystalline silicon ingots. It was expected that twins will appear on facets existing at the grain boundary–solid–liquid triple line. Necessary conditions for the existence of facets were derived and it was shown that twinning remains a function of the probability of nucleation of twinned nuclei. It was demonstrated that this probability was in qualitative agreement with the experimental observation for cases where the grain orientation was such that an angle of 132° occurs between a facet and a grain boundary. However, full validation of the model requires accurate values of interfacial energies at the melting point, which were currently lacking.

On the Twinning Occurrence in Bulk Semiconductor Crystal Growth. T.Duffar, A.Nadri: Scripta Materialia, 2010, 62[12], 955-60