Polytypism in SiC: Theory and experiment

• Criticism of dislocation theory of polytypism: contrary to the theory 27R is not a derived polytype of 4H structure.
• Cluster concept of polytypism. Stoichiometric clusters Si2C2 (dimer) and Si3C3 (trimer).
• Consideration of symmetry of one-dimensional chains composed of clusters.
• Polymer analogy of polytypic growth in SiC: 15R polytype.
• A probabilistic approach on the emergence of SiC polytypes.

Theoretical and experimental studies of the phenomenon of polytypism in silicon carbide obtained by the Lely method have been presented. It is shown that the elementary theory of polytypism can be built on the basis of very general considerations, taking into account the physical and chemical parameters of the growth process, as well as the steric factor and the possible symmetry of elementary clusters involved in the growth process.