Density functional theory was used to study the diffusion of Cs in crystalline bulk SiC. The Cs point defects and Cs - vacancy clusters were investigated with regard to stability and structure. The most stable state for the Cs impurity in SiC, under n-type doping conditions, was found to be a negatively charged Cs atom substituting for a C atom and bound to two Si vacancies (CsC-2VSi3-). Bulk diffusion coefficients were estimated for several Cs impurity states. The CsC-2VSi3- defect structure was found to have the lowest overall activation energy for diffusion with a value of approximately 5.14eV. This activation energy agrees well with diffusion activation energies estimated for Cs in SiC based on high temperature integral release experiments.

Cs Diffusion in Cubic Silicon Carbide. D.Shrader, I.Szlufarska, D.Morgan: Journal of Nuclear Materials, 2012, 421[1-3], 89-96