Investigation Of The Irradiation Defects In Fast Neutron Irradiated Czochralski Silicon

Translation mechanism of fast neutron irradiation defects and the effects of fast neutron irradiation defects on oxidation induced defects in Czochralski silicon (CZ-Si) in annealing process was investigated systemically.The experiment results indicated that the change trend of the concentration of interstitial oxygen ([Oi]) in fast neutron irradiation CZ-Si fluctuated largely with temperature increasing after annealing from 100℃to 700℃, especially between 500℃and 700℃. There are large quantity of metastable defects in fast neutron irradiation CZ-Si. During heat-treatment process at different temperature, the conversion of the metastable defects make [Oi] fluctuate largelyOxygen introduced defects is connected with pre-annealing temperature after two-step annealing in fast neutron irradiation CZ-Si. Pre-annealing at 500℃, the formation of irradiation defects V2O2, O-V-O is the main reason of the formation of dislocation loops and faults after two-step annealing in samples. Pre-annealing at 600℃, the appearance of three-dimensional vacancy clusters causes the precipitation of oxygen and after two-step annealing these area can form large faults and dislocation loop. When nnealing temperature runs up to 700℃, irradiation defects decompose and the main defects in sample is dislocation after two-step annealing. It can be concluded that oxygen introduced defects after two-step annealing is determined by defects that formed during pre-annealing at different temperature.The magic denuded zone(MDZ) of fast neutron irradiation CZ-Si is investigated. It was found that the behavior of the irradiated samples was different from the non-irradia- tion samples for the vacancy type defects induced by fast neutron irradiation. The results show that with increasing of the dosage MDZ have a tend of increasing earlier and decreasing later. When dosage is 5.9×1018 n·cm-2 the width of the MDZ is about 35μm; When dosage is 1.17×1019 n·cm-2, there is no denuded zone (DZ) but lots of microdefects (BMDs) on bulk.