Optical emission spectroscopy study for nitrogen–acetylene–argon and nitrogen–acetylene–helium 100 kHz and dc discharges

The optical emission spectroscopy was applied to investigate the middle frequency (100 kHz) and dc low pressure discharges, generated in the nitrogen–acetylene–argon and nitrogen–acetylene–helium mixtures, commonly used for deposits of carbon nitride thin layers. Changes in the emission intensities of the selected species: CN, CH, C, H, N2, N2+ as well as Ar, Ar+ and He, were studied as a function of the discharge current. Excitation processes occurring in the presence of argon and helium were compared and discussed. The N2–C2H2–Ar and N2–C2H2–He plasmas generated in the 100 kHz and dc glow discharges were characterized by the excitation (Ar, He, H), vibrational (CN, N2) and rotational (CN, N2+) temperatures. A significant deviation from the equilibrium state was observed for the plasma containing argon as well as helium.