Positron annihilation studies of γ-irradiated type Ib and IIa diamonds

Abstract

Cobalt-60 gamma irradiation readily created vacancy-type defects in type Ib diamond whereas none were found in type IIa. The defect is characterized by a positron lifetime of 130 ps and a main annealing stage centered at 270 °C. The vacancy is not a free vacancy, and is suggested to be a vacancy–self-interstitial complex. None of the optical absorption features in the experimentally accessible wavelength range of 400–1100 nm could be correlated with the positron data. Statement of novelty Gamma irradiations of type Ib diamond is shown to produce a vacancy–interstitial complex observable by positron lifetime spectroscopy, and with characteristics very different from those of the isolated monovacancy.