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 Ωcm. 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.