Lattice damage caused by the irradiation of diamond

Diamond is perceived to be radiation-hard, but the damage caused to the diamond is not well understood. The intrinsic defects (vacancies and interstitials) which are created by radiation damage are immobile at room temperature in diamond, unlike in silicon. Therefore, once the mechanisms of damage are understood for one type and energy of the particle, the dose and energy dependence of irradiation by other particles at a range of energies can be extrapolated. When a crystal is irradiated, the generation rates of vacancies and self-interstitials are generally determined by optical or electron paramagnetic resonance (EPR) spectroscopy experiments carried out after the irradiation has stopped. However, as the irradiation proceeds some of the carbon atoms displaced from their lattice sites may relax back into the vacant site, and the damage event will not be observed in the later measurement. In this paper, the mechanisms for radiation damage by charged particles, in particular electrons and photons are investigated. The kinetics of damage creation and the subsequent recombination of closely paired vacancies and self-interstitials are studied by a combination of theoretical modelling and optical and EPR spectroscopy to indicate the eventual lattice damage caused to the diamond. (C) 2002 Published by Elsevier Science B.V.