A comprehensive study was made of 2.5 to 10MeV electron-irradiated Czochralski material by using positron lifetime and Doppler broadening spectroscopy. Eight samples, ranging from heavily-doped n-type to heavily-doped p-type, were irradiated simultaneously at room temperature in order to facilitate quantitative comparisons of the samples. The effect of O impurity was also investigated by comparison with O-free material. In the case of lightly-doped material (dopant concentration less than 5 x 1016/cm3), the irradiation damage was dominated by free and negatively charged divacancies at the doses which were used (1.2 x 1018/cm2). In the case of heavily-doped materials (dopant concentrations higher than 5 x 1017/cm3), vacancy-dopant complexes predominated. Some of these involved divacancies and, in these samples, very high introduction rates (1 to 4/cm) were expected. In heavily B-doped material, evidence was found for thermally activated trapping by B di-vacancy complexes. The association of di-vacancies with P, Sb and B dopants was found to modify significantly the Doppler S-parameter; relative to the value for free divacancies.

Impurity-vacancy complexes in electron-irradiated silicon V.Avalos, S.Dannefaer: Physical Review B, 1998, 58[3], 1331-42