Observation of an Injection Dependent Lifetime Effect in Highly Hydrogenated Boron Doped Wafers

The correlation between hydrogen content and boron-oxygen related degradation is under debate. In this study surface passivated boron doped silicon wafers with different hydrogen content were illuminated at room temperature with three different light intensities. Their lifetime degradation was monitored with quasi-steady state photoconductance. A characteristic degradation that is separated into a fast and a slow decay characteristic for all light intensities is expected for such wafers. However, with increasing hydrogen content, we observe that the initial lifetime prior to illumination decreases, reducing the fast decay part of the degradation curves. For low intensity illumination the samples with reduced initial lifetimes follow the predicted degradation curve and show only the slow decay. For higher light intensities the degradation curves differ considerably; there is first a temporary lifetime increase before the decay sets in.