Analysis of performance limiting material properties of multicrystalline silicon

We present progress of the analysis of multicrystalline silicon and of improvements of our understanding of material related performance limits of solar cells. Aspects covered are advanced numerical simulation, experimental results on carrier lifetime distributions, detailed analysis of the defect luminescence spectrum, and findings about breakdown behaviour. Modelling of impurity redistribution, specifically iron, with respect to high temperature steps enlightens mechanisms governing the phosphorus diffusion and aluminium gettering in heterogeneous systems. Evidence of outdiffusion of metallic impurities from grain boundaries, after high temperature steps, is given by analysing spatially resolved carrier lifetime measurements. In addition to lifetime, we present defect luminescence spectra measured by photoluminescence spectroscopy, including an interpretation of the origin of a remarkably temperature stable emission line at 838 meV. Finally, defect luminescence is connected to the origin of pre-breakdown of solar cells at reverse bias, a topic which is of high interest especially in context with the increased usage of purified metallurgical grade silicon