Hydrogen passivation of ribbon silicon-electronic properties and solar cell results

Hydrogen bulk passivation of crystal defects plays a major role during solar cell processing of multicrystalline ribbon silicon material. In this study, the authors concentrate on the diffusion and effusion kinetics of hydrogen in different ribbon silicon materials (RGS (Bayer AG), EFG (ASE), String Ribbon (Evergreen Solar)). Electronic properties like majority charge carrier mobility and concentration were investigated by temperature dependent Hall measurements. Deuterium profiles determined with the SIMS method reveal that the diffusion velocity is strongly linked with the interstitial oxygen concentration present in the different materials. Taking into account these results, a confirmed record high efficiency of 12.5% on Bayer RGS silicon (4 cm²) was achieved with an optimized hydrogen passivation step