Wafers from a hybrid silicon ingot seeded in part for High Performance Multicrystalline, in part for a quasi-mono structure, are studied in terms of the effect of gettering and hydrogenation on their final Internal Quantum Efficiency.The wafers are thermally processed in different groups – gettered and hydrogenated. Afterwards, a low temperature heterojunction with intrinsic thin layer cell process is applied to minimize the impact of temperature. Such procedure made it possible to study the effect of different processing steps on dislocation clusters in the material using the Light Beam Induced Current technique with a high spatial resolution. The dislocation densities are measuredusing automatic image recognition on polished and etched samples. The dislocation recombination strengths are obtained by a correlation of the IQE with the dislocation density according to the Donolato model. Different clusters are compared after different process steps. The results show that for the middle of the ingot, the gettering step can increase the recombination strength of dislocations by one order of magnitude. A subsequent passivation with layers containing hydrogen can lead to a decrease in the recombination strength to levels lower than in ungettered samples.

Sponge-LID decreases the Al-BSF cell efficiency by up to 10 %rel. and is only partially recoverable at 200°C. This contributionshows that Sponge-LID occurs at and near most grain boundaries, but only in the centre of the affected cell.  Furthermore,Sponge-LID is not the only type of LID in the silicon bulk. High-resolution Light Beam Induced Current mapping reveals localinternal quantum efficiency losses of up to 8 %rel. at dislocation clusters and small angle grain boundaries, which recover(nearly) fully at 200°C. Nevertheless, this dislocation-related LID appears to reduce the Al-BSF efficiency by less than 1 %rel.

In this contribution, we provide an insight into the light-induced degradation of multicrystalline (mc-) silicon caused by copper contamination. Particularly we analyze the degradation kinetics of intentionally contaminated B- and Ga-doped mc-Si through spatially resolved photoluminescence (PL) imaging. Our results show that even small copper concentrations are capable of causing a strong LID effect in both B- and Ga-doped samples. Furthermore, the light intensity, the dopant and the grain quality were found to strongly impact the degradation kinetics, since faster LID was observed with stronger illumination intensity, B-doping and in the grains featuring low initial lifetime. Interestingly after degradation we also observe the formation of bright denuded zones near the edges of the B-doped grains, which might indicate the possible accumulation of copper impurities at the grain boundaries.

Although several advances have been made in the characterization and the mitigation of light-induced degradation (LID), industrial silicon solar cells still suffer from different types of light-induced efficiency losses. This review compiles four decades of LID results in both electronic- and solar-grade crystalline silicon. The review focuses on the properties and the defect models of boron-oxygen LID and copper-related LID. Current techniques for LID mitigation are presented in order to reduce cell degradation and separate copper-related LID from boron-oxygen LID. Finally, the review summarizes recent observations of severe LID in modern multicrystalline silicon solar cells.