Migration kinetics of ion-implanted beryllium in glassy carbon

Migration kinetics of low-concentration implanted 7Be in glassy carbon has been studied by the modified radiotracer technique at temperatures 1285 °C and 1340 °C. The annealed sample concentration profiles show two distinctive components: (i) Main profile broadening assigned to beryllium trapping in defects during annealing. (ii) Tail parts on both sides of the profile maximum related to faster migration. Of the latter the profile representing bulk diffusion lies on the region free of defect influence and is well described by concentration-independent diffusivity. The features of the concentration profile broadening towards the sample surface indicate partial Be trapping in defects upon annealing. Diffusion coefficients for Be migration in the damaged and defect-free material are provided. It is concluded that light impurity atom diffusion in glassy carbon is of the same order of magnitude as diffusion in diamond.