Light-induced degradation of very low resistivity multi-crystalline silicon solar cells

An J_sc degradation under illumination has been measured for finished solar cells processed from multicrystalline B-doped Si-substrates with resistivities below 0.1 Ω cm. This phenomenon has been studied as function of the different applied processing steps and as function of the boron- and oxygen-concentration of the substrate. The observed effect is likely related to a reversible formation of boron-oxygen complexes, introducing traps in the bandgap. This behaviour is similar to what has been reported in literature for carrier lifetime instabilities of 1 Ω cm Cz-Si. The degradation was found to be fully reversible by a low-temperature anneal at about 200°C, provided that the degradation causing defects have not been passivated by hydrogenation