Interpretation of x-ray photoelectron spectra of elastic amorphous carbon nitride thin films

We report the synthesis and characterization of amorphous carbon nitride (C Nx) thin films using a direct current magnetron reactive sputter system. Na noindentation of the CNx films and amorphous carbon films deposited under s imilar conditions shows the CNx films are extremely elastic, that the addit ion of nitrogen fundamentally changes the mechanical properties of the film s, and that traditional methods of calculating the hardness and Young's mod ulus may not be valid. X-ray photoelectron spectroscopy (XPS) of the N(1s) and C(1s) core levels show multiple bonding arrangements. In a new interpre tation of the XPS data, the two predominant N( 1s) spectral features have b een identified, based on comparison to reference data in the literature, as those belonging to nitrogen in a four-bond arrangement and nitrogen in a t hree-bond arrangement, independent of hybridization. The formation of a fou rth bond allows nitrogen to substitute for C atoms in a carbon-based graphi tic system without the formation of dangling bonds or unfilled states. The relationship between nitrogen incorporation in a carbon-based ring structur e and measured film properties is rationalized based on previously publishe d models. (C) 1999 American Institute of Physics. [S0003-6951(99)00122-9].