Origin of small-angle grain boundaries during directional solidification in multicrystalline silicon

The formation of small-angle grain boundaries (SAGBs) during directional solidification of multicrystalline silicon was directly observed in situ. SAGBs were confirmed by preferential etching due to the aggregation of dislocations at the solid/melt interface. Dislocations self-arrange by polygonization into an energetically favorable SAGB configuration. The misorientation of the SAGBs increases during crystal growth, possibly through the continual incorporation of dislocations. The present results suggest that there is considerable dislocation motion at the solid/melt interface and polygonization can occur during solidification.