Radiation defects and their annealing behaviour in ion-implanted diamonds

The major studies, in our laboratories, which led to a model of defect crea tion and annealing during ion implantation into diamond, are discussed. Fro m the data that have been gathered, the radiation-defect processes are cons istent with simple vacancy-interstitial atom creation in the collision casc ades. Accordingly, it has been assumed that, owing to its high radiation ha rdness, displacement spikes do not play an important role in the generation of defects in diamond. The point defects that are created can migrate by d iffusion at suitable temperatures. Diffusing self-interstitial atoms can ei ther meet up with vacancies and annihilate them, or diffuse out of the laye r being implanted (or which had been implanted). The fraction that escapes before annihilating vacancies depends on the depth-width omega of the layer and the annealing temperature. With the aid of this model, two implantatio n-doping routines called cold-implantation-rapid-annealing (CIRA) and low-d amage-drive-in (LODDI) have been devised. It is possible to generate p- and n-type layers in diamond using these routines, even when using keV implant ations, From this theory, it is noted that MeV implantations should greatly increase the quality of the doped layers. (C) 2000 Elsevier Science B.V. A ll rights reserved.