A deep level transient spectroscopy study on the interface states across grain boundaries in multicrystalline silicon



Degrading the recombination activities of grain boundaries (GBs) is essential to improve the efficiency of multi-crystalline silicon (mc-Si) based solar cells. We apply the deep level transient spectroscopy technique to detect interface states at Σ3 and Σ9 GBs in mc-Si. The density of interface states close to midgap is found comparable for both as-grown GBs. Gettering or hydrogenation leads to shallower states with a smaller capture cross section and lower density. Recombination activity reduction for Σ3 GBs is stronger than for Σ9 GBs especially after hydrogenation. Both the analysis approach and experimental results could be applied for a specific GB engineering of mc-Si based solar cells. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)