Highly spatial resolved photoluminescence characterization of intra-grain defects in recent multicrystalline Si wafers for solar cells was performed. Comparison of band-edge PL intensity mapping with minority carrier lifetime mapping on a whole wafer showed that low PL intensity regions correspond to short lifetime regions. PL microscopic mapping revealed that micron-sized defects were present in these regions. It was also confirmed that grain boundaries were not active recombination centres. Low-temperature PL spectra were investigated, and dislocation-related lines, D1–D4, were observed only in the defect areas. It was concluded that these defects were ascribable to dislocations decorated with heavy metals and responsible for great degradation of lifetime.

Analysis of Intra-Grain Defects in Multicrystalline Silicon Wafers by Photoluminescence Mapping and Spectroscopy. H.Sugimoto, M.Inoue, M.Tajima, A.Ogura, Y.Ohshita: Japanese Journal of Applied Physics, 2006, 45[25], L641-3