Process monitoring of multicrystalline silicon solar cells with quasi-steady state photoconductance measurements

Abstract

Multicrystalline silicon (mc-Si) solar cell efficiency is strongly related to the bulk material lifetime due to the low electronic quality. The minority carrier lifetime of multicrystalline silicon can vary greatly during the high temperature furnace steps involved in cell processing. Quasi-steady state photoconductance (QssPc) measurements were used to monitor the lifetime of different mc-Si substrates and process sequences. It is important to identify the beneficial or detrimental processing steps, to minimize recombination (and therefore efficiency) at the completion of processing. The benefits of phosphorus diffusions and aluminum alloys were identified, while oxidations of ungettered substrates and metallization contributed to increased recombination and decreased effective lifetimes. Show more