Methods of production, structure, and properties of film materials based on the carbon—nitrogen system (survey)

About 50 papers devoted to producing and investigating the properties of carbon nitride films are critically reviewed. It is shown that reasonable experimental confirmation of synthesis of the hypothetical β-C3N4 does not yet exist. Carbon nitride films can be produced practically by all PVD and CVD methods. They may contain up to 50% nitrogen, have an amorphous structure, and atoms in carbon nitride sp2-bonded. The microstructure of amorphous CN films is mostly based on two types of clusters—cyanogen polymers and graphite-like domains with carbon atoms partially substituted by nitrogen. The relation between two microstructure types depends on the deposition conditions and crucially influences the film properties. The smaller the graphite-like clusters size and the more chaotically they are oriented in the film the harder will be the film. The factor which influences most the type of film microstructure and properties is the ion bombardment of the film during the deposition. The small friction coefficient, high elasticity, and relatively high hardness of nitride carbon films may make them useful as protective coatings of a storage medium in computers.