Thermal expansion coefficient, mechanical and structural properties of hydrogenated carbon nitrides

Amorphous hydrogenated carbon nitride films (a-C:H:N) deposited by plasma enhanced chemical vapor deposition of methane (CH4) and nitrogen (N2), under low (− 200 V) and high (− 800 V) bias voltage are investigated. The nitrogen content was obtained from X-ray photoelectron spectroscopy and nuclear reaction analysis. Raman measurements were performed at 514 nm (visible) and 244 nm (UV) wavelengths. Mechanical properties (Young's modulus and hardness) and thermal expansion coefficient (TEC) were studied using the bending beam method. Raman spectroscopy shows that the incorporation of nitrogen in a-C:H reduces the disorder in the film, independent of the initial structure of the a-C:H films (tetrahedral-, diamond-, or graphitic-like). The TEC is related to the Raman parameters associated with the degree of sp2 ordering (aromatic rings) in the film structure, increasing with the nitrogen incorporation.