Incorporation of lithium and nitrogen into CVD diamond thin films

High concentrations of lithium (~5 × 10¹⁹ cm⁻³) and nitrogen (~3 × 10²⁰ cm⁻³) have been simultaneously incorporated into single-crystal and microcrystalline diamond films using Li₃N and gaseous ammonia as the sources of Li and N, respectively. Using sequential deposition methods, well-defined localised layers of Li:N doped diamond with a depth spread of less than±200 nm have been created within the diamond. The variation in Li:N content and amount of diffusion within the various types of diamond suggests a model whereby these atoms can migrate readily through the grain-boundary network, but do not migrate much within the grains themselves where the diffusion rate is much slower. However, the high electrical resistivity of the doped films, despite the high Li and N concentrations, suggests that much of the Li and N are trapped as electrically inactive species.