TRANSMISSION ELECTRON-MICROSCOPE STUDY OF NEUTRON IRRADIATION-INDUCEDDEFECTS IN SILICON

Commercial Czochralski-grown silicon (Cz-Si) and float-zone silicon (F z-Si) wafers were irradiated with fission neutrons at various fluences from 10(19) to 10(22) n/cm(2) at temperatures ranging from 473K to 10 43K. The irradiation induced defect structures were examined by transm ission electron microscopy and ultra high voltage electron microscopy, which were compared with Marlowe code computer simulation results. It was concluded that the vacancy-type damage structure formed at 473K w ere initiated from collapse of vacancy-rich regions of cascades, while interstitial type defect clusters formed by irradiation above 673K we re associated with interstitial oxygen atoms and free interstitials wh ich diffused out of the cascades. Complex defect structures were ident ified to consist of{113} and {111} planar faults by the parallel beam illumination diffraction analysis.