To clarify the role of grain boundaries in Fe sinks and carrier recombination centres, Fe distributions and their chemical states were studied before and after gettering. They were measured by the X-ray microprobe fluorescence and the X-ray absorption in the near-edge structure using synchrotron methods. To determine the crystallographic orientation of the grain boundaries, electron backscatter diffraction measurements were performed. The distribution of electric active defects was characterized by electron-beam-induced current measurements. Before gettering, the Fe was distributed in the small grain and its chemical state was similar to that of iron oxide. After gettering, the Fe was redistributed along the small angle grain boundary, and its chemical state was similar to the iron silicide complexed with the iron oxide. Regarding the electrical activity, high carrier recombination was observed along the small-angle grain boundary. On the other hand, Σ3 grain boundaries were relatively weak impurity sinks and showed a low recombination activity.

Study of Iron Distribution and Electrical Activities at Grain Boundaries in Polycrystalline Silicon Substrate for Solar Cells. K.Arafune, E.Ohishi, H.Sai, Y.Terada, Y.Ohshita, M.Yamaguchi: Japanese Journal of Applied Physics, 2006, 45[8A], 6153-6