A fast, non-destructive, non-contact and preparation free measurement method is introduced which iscapable of distinguishing between boron and gallium doped PV silicon bulk feedstock materials (slugs, ingots oruneven shaped material pieces). The method consists of high-injection minority carrier lifetime measurement andhigh intensity laser treatment. The microwave photoconductance decay method is applied as a high injection carrierlifetime measurement.The boron or gallium dopant species can be determined from the polarity of the carrier lifetime change caused by theapplied laser treatment sequence. All boron doped samples show negative carrier lifetime change, while the lasertreatment increases the lifetime of most gallium doped pieces. The negative lifetime change of boron doped silicon iscaused by the formation of boron-oxygen LID defects. Dissociation of iron-acceptor pairs is found to be responsiblefor the lifetime increase in the gallium doped samples.The dynamics of lifetime change caused by the laser treatment is discussed in detail, optical dissociation of irongallium pairs is found to be much slower than in the case of iron-boron pairs, while light induced degradation showsthe expected dynamics.Keywords: gallium doping, light induced degradation, iron-acceptor pairs, carrier lifetime
