Positron annihilation studies of detector grade n-type silicon irradiated with 140Â MeV oxygen (O6+) ions

Detector grade n-type float-zone silicon irradiated with 140 MeV O6+ ions to a dose of 5×1015 particles/cm2 was studied by positron annihilation spectroscopy. Vacancy clusters containing five vacancies were detected in the irradiated sample. Isochronal annealing studies of the irradiated sample reveal the dissociation of five-vacancy clusters and formation of vacancy agglomerates V3, V6 and vacancy-oxygen complexes in the temperature range 250-500 °C. The vacancy-oxygen complexes dissociate at 550 °C and released vacancies agglomerate around 600 °C to form voids comprising 10 vacancies. In the temperature range 600-700 °C, the voids dissociate and around 750 °C advanced vacancy-oxygen complexes VmOn (n>m) form.