SEARCH FOR DIFFUSION OF LI IMPLANTS IN NATURAL AND POLYCRYSTALLINE CVD DIAMOND

Secondary ion mass spectrometry measurements of the depth profiles of Li implanted into natural diamond under various implantation (channel and random incidence) and annealing (up to 1400-degrees-C for 1 h) conditions show no diffusion whatsoever of Li in diamond. In contrast, the profile of Li implanted into a polycrystalline CVD diamond film does broaden upon annealing and exhibits a long tail extending deep (more than 10 mum) into the diamond film. This diffusion, however, must be associated with the polycrystalline nature of the material and is therefore governed by grain boundary diffusion. The lack of Li diffusion in single-crystal diamond has important implication regarding the possibility of introducing Li into diamond in an attempt to achieve n-type doping.