IR characterization of a-C:H:N films sputtered in Ar/CH4/N2 plasma

Amorphous nitrogenated carbon films (a-C:H:N) were deposited by rf magnetron sputtering of a graphite target in an Ar/CH4/N2 plasma. The films were characterized by infrared spectroscopy. An increase in the intensity of absorption maximum at 3300–3400 and 1620 cm−1 of the IR spectra was observed. For high nitrogen concentrations, a new maximum appears at 2150 cm−1 indicating that the C and N atoms are chemically bonded in the film. The analysis of the broad absorption band observed between 1700 and 1000 cm−1 was made. Deconvolution of this band showed a six band system, indicating a lack of aromatic structures. The content of nitrogen and sp2 bonded carbon in the films was seen to increase with a growth of the N2 partial pressure in the deposition gas.