Silicon carbide has a number of properties comparable to that of diamond, such as hardness, high chemical, thermal and mechanical stability as well as similar optical properties. SiC is, on the other side, also a semiconductor as elemental silicon, but with a wider bandgap. Manifold possibilities for technical applications result from this combination of properties. The similarity with silicon and diamond can be traced back to the same structure type. SiC is, however, characterized by a multitude of polytypes. The largest proportion of SiC, with technical grade quality, is produced by the Acheson process, i.e. the reaction of SiO2 with carbon. Crystals of high purity and with a defined structure can be obtained by sublimation of Acheson-SiC. CVD methods are best suited for the production of thin SiC films, while SiC fibers result from thermolysis of polycarbosilanes.
