Isothermal annealing of electron radiation damage in natural semiconducting diamond

Two natural semiconducting diamonds were pre-heated at 13500C irradiated at 770 K with approximately 2 x 1016 electrons/cm2 at an energy of 1 MeV and heated for successively increasing periods of time at temperatures in the range 200 to 12000C. The annealing of the irradiation damage exhibits at least three direct stages and one reverse stage. Direct and reverse annealing are defined as producing changes, respectively, in the opposite direction to, and in the same direction as, those produced by the irradiation damage. Direct annealing at the lower temperatures may be due to the trapping, by stationary vacancies, of mobile carbon interstitials released by the partial disintegration of interstitial clusters. The reverse annealing could be produced by the interchange of carbon interstitials with substitutional trivalent impurities. A number of processes may be responsible for the direct annealing at the higher temperatures. One of these may be the interchange of mobile vacancies with interstitial trivalent impurities. (author)