In the research of semiconducting materials, ion beam-induced charge collection (IBICC) technique can provide interesting and straightforward information about the different electronic device characteristics. This nuclear microprobe technique was used for the qualitative analysis of charge collection efficiency spatial distribution in three different types of EFG silicon material. Using IBICC technique, we studied the influence of present 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 IBICC technique could be applied to provide spatial information about the position of electrically active defects, and/or their activation or deactivation during subsequent processing. (C) 2002 Elsevier Science B.V. All rights reserved.