Characterization of multicrystalline silicon wafers by non-invasive measurements

Non-invasive transient photoconductance measurements of large grain multicrystalline silicon wafers (ρ=1 Ω cm) are presented. It is shown that the surfaces of untreated wafers can be characterized as infinite sinks for excess charge carriers. The value 24.5 cm2 s−1 for the minority carrier diffusion constant was determined in all samples. So in untreated wafers, surface recombination yields a known contribution to the decay time measured and the volume lifetime can be determined. Application of these measurements as a standard characterization of multicrystalline silicon wafers is discussed.