Origin of trapping in multicrystalline silicon

Defect sites in silicon, which temporarily capture excess charge carriers (traps), are a promising source of information on defect structures relevant for photovoltaic application of the material. In this work the correlation between traps in p-type silicon, structural crystal defects, and impurities is explored in order to find the origin of these traps in multicrystalline silicon. The trap density is compared to the density of different impurities and structural crystal defects. These comparisons reveal that the trap density is positively correlated with the oxygen density and negatively correlated with the density of the metallic impurities analyzed. In addition we show that structural crystal defects are necessary but not sufficient for the existence of high trap densities. In summary, structural crystal defects that are decorated by oxygen precipitates arise as likely origin of trap centers.