Nitrogen incorporation into tetrahedral hydrogenated amorphous carbon

Structural changes induced by the incorporation of nitrogen into ta-C:H fil ms have been studied by Electron Energy Loss Spectroscopy, X-Ray Photoelect ron Spectroscopy Fourier Transformed Infrared Spectroscopy and Ultraviolet- Visible Spectroscopy. ta-C:H films have been synthesised using a low pressu re Electron Cyclotron Wave Resonance (ECWR) source which provides a plasma beam with a high degree of ionisation and dissociation. Nitrogen was incorp orated by adding Nz to the C2H2 plasma used for the deposition of ta-C:H fi lms. The N/C atomic ratio in the films rises rapidly until the N-2/C2H2 gas ratio reaches three, and then increases more gradually while the depositio n rate decreases steeply. Chemical sputtering of the forming films and the formation of molecular nitrogen within the films limit the maximum nitrogen content to about N/C = 0.6. For low nitrogen content the films retain thei r diamond-like properties, however as N/C atomic ratio increases, a polymer ic-like material is formed, with >C=N- structures and terminating C=N and N H groups that decrease the connectivity of the network.