Ion beam modification of diamond was important for achieving doping by means of ion implantation, critical dose for graphitization of diamond as well as for understanding the thermal annealing process. Diamond was a unique material, since it was a metastable form of carbon and it may transit into the stable graphite form upon the ion bombardment. A theoretical model for the description of the evolution of Li and B profiles after the ion implantation and annealing process was suggested in this paper. The model consists of three diffusion equations for defect density and doping atoms and also of rate equations for formed new bonds: dangling bond-doping atom. One could take into account the transition from the metastable diamond structure into the stable graphite form in the place where the defect density exceeds a critical volume density of defects Cdcr. For different layers (diamond and graphite) one could use different diffusion coefficients and rate constants for doping atoms. The results of numerical simulation modelling were in qualitative agreement with the experiments and the numerical fitting parameters were in the physically justifiable range.

Theoretical Model of Diffusion of Lithium and Boron Implanted in Diamond. Gadiyak, G.: Nuclear Instruments and Methods in Physics Research, Section B, 1997, 127-128, 256-9