The diffusion coefficient of Si in thin samples was estimated by analysing layer-growth kinetics during carbonisation using various growth techniques. The Si diffusivity could be described by the classic parabolic law, as well as by models which took account of the peculiarities of the carbonisation process. In general, low diffusion coefficients corresponded to layers with good morphological and structural properties. The best results were obtained by using chemical vapour deposition; followed by gas-source molecular beam epitaxy and by techniques which involved the use of elemental C as a source for carbonisation. All of the estimated diffusion coefficients were several orders of magnitude higher than for monocrystalline bulk material. The difference between thin monocrystalline layers, where growth saturated after a few nm, and thicker rough twinned or polycrystalline layers, was related to a change in Si diffusivity of more than 2 orders of magnitude. A similar behaviour was found for the best layers which were grown by means of gas-source molecular beam epitaxy.

The Diffusion Coefficient of Silicon in Thin SiC Layers as a Criterion for the Quality of the Grown Layers. V.Cimalla, T.Wöhner, J.Pezoldt: Materials Science Forum, 2000, 338-342, 321-4