Photoluminescence Analysis of Oxygen Precipitation around Small-Angle Grain Boundaries in Multicrystalline Silicon Wafers

We have investigated the correlation between deep-level photoluminescence and the density of small-angle grain boundaries in multicrystalline Si. A deep-level photoluminescence component around 0.87 eV, which we previously ascribed to oxygen precipitates, became lower and higher in the region with high and low density of small-angle grain boundaries, respectively. This can be explained by the differences in the availability of oxygen atoms around respective small-angle grain boundaries. We performed focused ion beam time-of-flight secondary ion mass spectroscopy on special points emitting extremely strong 0.87 eV emission, and detected a clustered area of $\text{}^16O¯$. This is strong evidence for the idea that the 0.87 eV band is due to oxygen precipitates.