Positron annihilation studies of Czochralski-grown silicon annealed under pressure

Two positron techniques have been applied to study dynamics of oxygen preci pitation in Czochralski-grown silicon, annealed under high (up to 1.4 GPa) pressure. Lifetime measurements were performed with 180 ps resolution; Dopp ler broadening with a variable-energy slow-positron beam. Different thermal treatings rise the mean lifetime of positrons from 222 ps in as-grown samp les up to 227 ps. In samples with a high (up to 85%) amount of oxygen preci pitated, an intermediate (550-800 ps) lifetime is observed.