Intrinsic point defect population in polycrystalline silicon is of the particular importance due to the influence on the electronic properties of material. A study of intrinsic point defect behavior is additionally complicated due to the interaction with the present impurities and different structural defects. Experiments were performed on EFG polycrystalline silicon material rich with carbon and different structural defects such as dislocations and various grain boundaries. Samples were irradiated with gamma-rays from a Co-60 source to the doses of 300 Mrad to introduce simple point defects into the bulk of the material. The results obtained with deep level transient spectroscopy (DLTS) showed that upon formation of the vacancy interstitial pairs, silicon selfinterstitials get trapped by larger structural defects, creating therefore a vacancy rich bulk of the material. (C) 2002 Elsevier Science B.V. All rights reserved.