The effects of impurities on the light-induced degradation of hydrogenated amorphous silicon

Amorphous silicon samples with an intentionally modulated impurity content at concentrations below 1 at.% were grown by the glow discharge deposition technique. The impurity profiles were determined by secondary-ion mass spectroscopy (SIMS) measurements and the spatial distributions of deep defects were determined by junction capacitance profiling measurements before and after light-induced degradation. For the case of intentionally added carbon, we found a significant enhancement in the concentration of light induced defects in regions with higher impurity levels such that a carbon level of 0.5 at.% leads to an additional $\text{(1–2) × 10}{}^{16}\text{cm}{}^{\mathrm{-3}}$ increase in defects after light soaking.