Impact of nickel contamination on carrier recombination in n- and p-type crystalline silicon wafers

The effect of Ni surface contamination on carrier recombination after high temperature processing of crystalline silicon wafers has been studied for a range of n- and p-type resistivities. The results suggest that the presence of Ni precipitates at the wafer surfaces, formed during cooling, dominate the measured lifetimes. These precipitates exhibit a greater impact on the low-injection lifetime in p-type samples than in n-type. In addition, the injection-dependent lifetime curves for the n-type samples changed from increasing to decreasing with injection-level as the resistivity increased above approximately 10 Ω cm. In most cases, the surface recombination velocity attributable to the presence of these Ni precipitates at the oxidized surfaces increased linearly with the Ni dose.