Synthesis of superhard and elastic carbon nitride films by filtered cathodic vacuum arc combined with radio frequency ion beam source

Superhard and elastic carbon nitride films with hardness and elastic recovery of 47 GPa and 87.5%, respectively, were synthesized by using a double-bend filtered cathodic vacuum arc combined with radio-frequency nitrogen ion beam source. The bombardment of energetic nitrogen atom onto the growing film surface results in the high atomic ratio of N/C (0.4), which contributes to the high sp(2) content and the formation of a five-membered ring structure in the carbon nitride film at room temperature. The buckling of the five-membered ring basal planes may facilitate cross-linking between the planes through sp(3) coordinated carbon atoms. A rigid three-dimensional network is formed, which contributes to the high hardness and elastic recovery of the deposited films.