Variable-range hopping conduction, which was attributed to the formation of graphite sp2 bonds, could be generated by high-dose ion implantation. With increasing implantation temperature, the ion dose which was required to cause conduction increased due to self-annealing effects. It was assumed that the ions could not have formed displacement spikes. Equations which were based upon interstitial-vacancy generation and recombination were derived in order to describe damage formation and annealing in diamond during ion implantation, and were applied to published data. It was found that the model fitted these data well, and was also consistent with recent results on interstitial-vacancy generation and the interaction of these defects in electron-irradiated diamonds.

Graphitization and Related Variable-Range-Hopping Conduction in Ion-Implanted Diamond. J.F.Prins: Journal of Physics D, 2001, 34[14], 2089-96