A field-enhanced diffusion with optical activation reactor was constructed, tested, and employed to diffuse sulfur and sodium into polished, natural diamond plates. Various chemical sources of sulfur were used for diffusion from the gaseous, liquid, and solid phases. Diffusion coefficients in the range of 10-15cm2/s to 10-14cm2/s at 450 to 1050C, were calculated for sulfur from concentration profiles determined from secondary ion mass spectroscopic analysis. Sulfur demonstrated n-type behavior with an activation energy of 0.9eV. Sodium was found to diffuse into diamond with an average diffusion coefficient of 7.2 x 10-14cm2/s at 750C. The different sources of sulfur provided qualitative information about competing mechanisms in the diffusion process.

Sulfur and Sodium: Diffusion of Potential Donors into Natural Diamond. West, M.K., Prelas, M.A., Tompson, R.V., Khomich, A.: Journal of Wide Bandgap Materials, 2002, 10[2], 129-48