Correlation between bonding structure and mechanical properties of amorphous carbon nitride thin films

Amorphous carbon nitride thin films were prepared in a dual ion beam sputtering (DIBS) system. The N/C atomic concentration ratio ranged between 0.3 and 0.5 as determined by quantitative X-ray photoelectron spectroscopy (XPS) of the surface. Fourier Transform Infrared spectroscopy (FT–IR), XPS and X-ray Absorption Spectroscopy (XAS) were used to obtain information about the different types of bonding present in the films. The hardness and the Youngʹs modulus of the samples were determined by nanoindentation measurements. The hardness varied in the range 15–30 GPa with Youngʹs modulus between 170 and 250 GPa. In order to explain the measured hardness, some of the films are considered as heterogeneous, in good agreement with the XPS, FT–IR and XAS data.