This chapter reviews the growth, structure, and properties of plasma-deposited a-C (N): H films. The hard amorphous hydrogenated carbon films (a-C:H) belong to the class of materials called “diamond-like carbon” (DLC). These materials are designated as DLC because of their superlative properties, similar to that of crystalline diamond—such as high hardness, low friction coefficient, high chemical and wear resistance, and high electrical resistivity. The carbon nitride solids are strongly related to research on DLC materials. DLC materials are thin-film amorphous metastable carbon-based solids, pure or alloyed with hydrogen, which have properties similar to those of crystalline diamond. This resemblance to diamond is because of the DLC structure, which is characterized by a high fraction of highly cross-linked sp3-hybridized carbon atoms. To obtain this diamond-like structure at ambient conditions, DLC film deposition techniques involve the bombarding of the film growing surface by fast particles with kinetic energy of the order of 100 eV. In β-C3N4 the carbon atoms should be sp3 hybridized. One of the ways to search for carbon nitride is the study of nitrogen incorporation into DLC films.