IBICC characterisation of defect structures in polycrystalline silicon

The low-cost polycrystalline substrates used in solar cell production suffer from a high concentration of impurities and defects. The influence of the particular defect on the electrical properties of material is important information and can be obtained only by the application of complementary characterisation techniques. The ion beam induced charge collection (IBICC) technique provides information about the spatial distribution of imperfections in charge collection, while the origin of these imperfections is not known. Therefore, various samples of edge-defined film-fed grown (EFG) and Czochralski (Cz) silicon were also analysed by deep level transient spectroscopy (DLTS), identifying the most important deep levels in the band gap. The influence of twin boundaries in EFG samples and high oxygen content of Cz material on the IBICC results are discussed as well as the IBICC-induced defects in test samples.