CXXXVIII. Application of dislocation theory to the polytypism of silicon carbide

Polytypism of silicon carbide can be understood if the assumption is made that the crystal grows out of the primary nucleus as a single sheet several atomic layers in thickness. The sheet winds itself spirally upwards along a bunch of screw dislocations which are situated at the spiral axis. If there are stacking faults in the original growth layer, they repeat themselves with the periodicity of the pitch of the screw throughout the crystal and thus determine the type and the dimensions of the unit cell. Similar typism occurs in graphite and possibly in diamond and other substances.