Defects in Czochralski-grown silicon crystals investigated by positron annihilation

A study on the defects introduced by electron irradiation, quenching and crystal growth processes in Czochralski-grown (Cz) crystals is presented. Measurements of lifetime and Doppler broadening of positron annihilation clarify the annealing behavior of the irradiation defects. The results of the irradiation studies are applied to analyze defects formed by quenching and those formed during the crystal growth process. It is found that oxygen clusters are formed by quenching and that the oxygen clusters are introduced in association with the formation of nuclei of stacking faults during the crystal growth processes.