Enhanced Wettability, Hardness, and Tunable Optical Properties of SiC_xN_y Coatings Formed by Reactive Magnetron Sputtering

Silicon carbonitride films were deposited on Si (100), Ge (111), and fused silica substrates through the reactive magnetron sputtering of a SiC target in an argon-nitrogen mixture. The deposition was carried out at room temperature and 300 °C and at an RF target power of 50–150 W. An increase in the nitrogen flow rate leads to the formation of bonds between silicon and carbon atoms and nitrogen atoms and to the formation of SiC_xN_y layers. The as-deposited films were analyzed with respect to their element composition, state of chemical bonding, mechanical and optical properties, and wetting behavior. It was found that all synthesized films were amorphous and represented a mixture of SiC_xN_y with free carbon. The films’ surfaces were smooth and uniform, with a roughness of about 0.2 nm. Depending on the deposition conditions, SiC_xN_y films within the composition range 24.1 < Si < 44.0 at.%, 22.4 < C < 56.1 at.%, and 1.6 < N < 51.9 at.% were prepared. The contact angle values vary from 37° to 67°, the hardness values range from 16.2 to 34.4 GPa, and the optical band gap energy changes from 1.81 to 2.53 eV depending on the synthesis conditions of the SiC_xN_y layers. Particular attention was paid to the study of the stability of the elemental composition of the samples over time, which showed the invariance of the composition of the SiC_xN_y films for five months.