Relationships between room temperature photoluminescence and electronic quality in multicrystalline silicon

We report here on a relationship between room temperature photoluminescence (RTPL) intensity in crystalline silicon and bulk material diffusion length improvements used to track solar cell performance. We present RTPL spectra and data on spatially resolved photoluminescence mapping over 100 cm² area EFG multicrystalline silicon wafers subjected to solar cell processing steps. A dramatic increase of band-to-band PL intensity by more than two orders of magnitude occurs after combined phosphorus diffusion, hydrogen passivation and aluminum alloying. This indicates that a large reduction in nonradiative recombination occurs during processing steps which improve cell efficiency through bulk minority carrier lifetime upgrading