The nature of damage in ion-implanted and annealed diamond

The nature of damage in diamond and its annealing are studied by monitoring the changes in electrical conductivity, material density and Raman spectra as a function of density of defects (implantation dose) and annealing temperature, Use is made of the marked differences between the properties of diamond and graphite to study the kinetics of the structural transformation of damaged diamond upon annealing. It is found that for low dose implantations (which create damage below a certain critical density N-c) the damaged diamond is rich in point defects and anneals back to diamond, via some well-defined defect states (most likely the split interstitial [100] dumbbell). In contrast, implantation to doses which create damage in excess of N-c. results in a fully amorphized. mostly sp(2) bonded, material which converts to graphite upon annealing. The onset of graphitization for heavily damaged diamond is found to be at about 800 K. (C) 1999 Elsevier Science B.V. All rights reserved.