Grain orientation and grain boundaries in cast multicrystalline silicon

We determined the orientations of the grains in cast multicrystalline BAYSIX-silicon. These were measured for each grain individually, using electron channeling patterns. Relative orientations between pairs of grains-and hence grain boundaries-were classified. An analysis of growth directions renders the result that grains seem to be oriented at random. However, it is shown that relative grain orientations are not 'random' but can mostly be described by special coincidence orientations, caused by multiple twinning. The grain structure of the ingot develops from far fewer independent nuclei than one would guess from simply looking at optical images of etched wafers. The experimental data can be reproduced if one assumes a few dominating grains that, during growth, twin up to the fourth order. (C) 1998 Elsevier Science S.A. All rights reserved.