Influence of P gettering thermal step on light-induced degradation in Cz Si

It is well-known that B-doped Cz Si solar cells suffer light-induced degradation due to a boron–oxygen defect which is responsible of a reduction in lifetime and hence efficiency. In this paper, the influence of a P gettering thermal step on Cz material quality is explored. It is shown, in a range of resistivities and oxygen contents, that P gettering is able to recover lifetime, reducing both ‘ingot growth-induced’ and ‘process-induced’ impurities, and allowing also for a reduction of the defect concentration after the thermal step. A comparison among different thermal processes related to the reduction of this specific defect has also been carried out with the aim of evaluating the effect of self-interstitials injection during thermal processing. Although the reduction in Cz-defect concentration is mainly due to the thermal treatment, specific environmental conditions into furnace can modify in some extent the reduction of defects. luate the effect of the defect activation in the performance of solar cells, PC1D simulations of a specific P/Al structure have been performed, and results show that efficiencies in the range of 18% can be achieved in the degraded state, with a reduction of more than half a point of efficiency from the non-degraded state in the best case.