Control of extended defects in cast multicrystalline silicon using polycrystalline template

Extended defects were controlled using polycrystalline silicon as a template for cast-growth of multicrystalline silicon. At the initial stage of growth, small randomly oriented grains with a high density of random type grain boundaries were obtained. With growth, the grain size increased and the fraction of random grain boundaries decreased. Electrical activity of defects was investigated and it was found that with growth, network of small angle grain boundaries became the most electrically active defects. This network of small angle grain boundaries were found to have a tilt angle less than 3° and were mainly found in elongating grains. The density of these highly electrically active grain boundaries increased with growth. This can be attributed to propagation and agglomeration of dislocations into small angle grain boundaries. The high density of random grain boundaries in this ingot may suppress dislocation propagation between grains, however they do not intersect elongating grains enabling dislocation propagation in elongated grains. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)