It was recalled that Li had been theoretically predicted to be a shallow donor in diamond in interstitial sites, and that many experiments had investigated the possibility of incorporating Li into diamond in order to impart n-type electrical conductivity, related to Li doping. Here, the status of Li impurities in diamond was described with regard to incorporation methods, Li diffusion analysis and characterization of the effects of Li diffusion upon diamond electrical and optical properties. New Li diffusion experiments were performed, under an electrical field, in order to enhance the diffusion of Li+. The diffusion coefficients of Li in diamond were found to be in the range of 10-15 to 10-14cm2/s at 400 to 860C. The activation energy for diffusion was estimated to be 0.26eV. This was much lower than the theoretically predicted value of 0.85eV. The application of an electrical field led to ambivalent results. No n-type conductivity was measured following Li in-diffusion, supporting the hypothesis that Li incorporated to a high concentrations remained clustered in the near-surface region.

Diffusion of Lithium in Diamond. Uzan-Saguy, C., Cytermann, C., Fizgeer, B., Richter, V., Brener, R., Kalish, R.: Physica Status Solidi A, 2002, 193[3], 508-16