Analysis of performance limiting material properties of multicrystalline silicon
The aim of the work presented is to improve the understanding of material related performance limits in multicrystalline solar cells. Modelling of impurity redistribution, specifically iron, due to high temperature steps enlightens mechanisms governing the phosphorus diffusion and aluminium gettering in heterogeneous systems. In the field of spatially resolved material characterisation beyond recombination lifetime measurements we present results for the trap density and the defect luminescence spectra on microscopical level which represent newly accessible material parameters connected to impurities and crystal defects and correlated to the performance limits of solar cells. In addition, the specifics and the origin of pre-breakdown of cells at reverse bias are investigated, a topic which is of high interest especially in context with the increased usage of purified metallurgical grade silicon.