- In the research of semiconducting materials, the ion beam induced charge collection (IBIC) technique can provide interesting and straightforward information about the different electronic device characteristics. This nuclear microprobe technique was used for the qualitative analysis of the spatial distribution of charge collection efficiency in several types of poly-Si material. We studied the influence of light impurities (oxygen, carbon) on electrical activity of extended defects. It is shown that oxygen segregating close to structural defects influences their electrical activity, while for carbon we did not observe the same effect. We demonstrated that IBIC can be applied to provide spatial information about the position of electrically active defects and its activation during subsequent processing.