Behaviour of metallic impurities at grain boundaries and dislocation clusters in multicrystalline silicon wafers deduced from contactless lifetime scan maps

Abstract

By means of a contactless microwave phase shift technique, the minority carrier lifetime and surface recombination velocity were measured in multicrystalline silicon wafers containing iron and chromium. The bulk lifetime can be deduced, leading to the determination of the concentration of interstitial iron [Fe-i] associated with boron, after pair dissociation annealing at 210 degreesC. It is found that [Fe-i] is higher in the vicinity of extended defects but decreases at the defects because the iron segregates irrespective of boron concentration and does not form pairs.