The annealing behaviour of defects in electron-irradiated samples was studied by using positron annihilation techniques. In the case of type-IIa material, after 3MeV electron irradiation to a dose of 1018/cm2, the main vacancy-type defect was determined to be the neutral monovacancy, V0. The trapping rate of positrons by V0 decreased during annealing at above 600C, but the annihilation of positrons trapped by vacancy-type defects was observed even after annealing at 900C. In the case of type-Ib specimens after irradiation, the main vacancy-type defect was the negative monovacancy. The formation of N-monovacancy pairs, N-V, was observed after annealing at 650C. The probability of annihilation of positrons and electrons with a broad momentum distribution was found to be increased by the trapping of positrons by N-V.

Annealing Behaviours of Defects in Electron-Irradiated Diamond Probed by Positron Annihilation. A.Uedono, K.Mori, N.Morishita, H.Itoh, S.Tanigawa, S.Fujii, S.Shikata: Journal of Physics - Condensed Matter, 1999, 11[25], 4925-34