Degrading the recombination activities of grain boundaries was essential to improve the efficiency of multi-crystalline silicon (mc-Si) based solar cells. The deep level transient spectroscopy technique was used to detect interface states at Σ3 and Σ9 grain boundaries in mc-Si. The density of interface states close to the mid-gap was found to be comparable for both as-grown grain boundaries. Gettering or hydrogenation led to shallower states with a smaller capture cross-section and lower density. Recombination activity reduction for Σ3 grain boundaries was stronger than for Σ9 grain boundaries especially after hydrogenation. Both the analysis approach and experimental results could be applied for a specific grain boundary engineering of mc-Si based solar cells.

A Deep Level Transient Spectroscopy Study on the Interface States across Grain Boundaries in Multicrystalline Silicon, J.Chen, E.Cornagliotti, E.Simoen, E.Hieckmann, J.Weber, J.Poortmans: Physica Status Solidi - Rapid Research Letters, 2011, 5[8], 277-9