Growth of carbon and nitrogen containing precipitates in crystalline solar silicon and their influence on solar cells

The growth mechanisms, structural, mechanical, and electrical properties of silicon carbide and silicon nitride precipitates in solar silicon are reviewed and some new aspects about the distribution of trace elements in these precipitates are reported in this review. SiC and Si3N4 precipitates may have detrimental impact on the quality of solar silicon material. Therefore intensive research has been done at these precipitates in the past, which is summarized first. The properties of the different types of precipitates reported in literature are then described in detail. Especially SiC precipitates may have detrimental impact on the electrical behavior of solar cells by causing severe ohmic shunting. Furthermore SiC precipitates are very hard and may harm the wafering process. An outlook of the impact of such precipitates on new cell concepts and new solar silicon materials, such as n-type, is given.