Mechanism of Diffusion of Carbon and Silicon Monooxides in a Cubic Silicon Carbide Crystal

The main processes that occur during diffusion of gaseous carbon CO and silicon SiO monoxides through a layer of a single-crystal silicon carbide SiC of the cubic polytype are described. This problem arises as a single-crystal SiC layer is grown by the method of matched atomic substitution due to the chemical reaction of a crystalline silicon substrate with CO gas. The reaction products are an epitaxial SiC layer and SiO gas. CO and SiO molecules are shown to decompose in the SiC crystal into individual atoms. The oxygen atoms diffuse over interstitial sites only in the [110] direction with the activation energy 2.6 eV. The Si and C atoms displace by the vacancy mechanism in the corresponding SiC sublattices with activation energies 3.6 and 3.9 eV, respectively, and only in the [110] direction.