Structural characterization of amorphous hydrogenated-carbon nitride (aH-CNx) film deposited by CH4/N2 dielectric barrier discharge plasma: 13C, 1H solid state NMR, FTIR and elemental analysis

The chemical composition and bond structure of polymer like amorphous hydrogenated carbon nitride (aH-CNx) thin films was studied by solid-state 13C and 1H MAS NMR spectroscopy, FTIR spectroscopy and elemental analysis. The hydrogenated CNx film was deposited on Si (100) substrate by CH4/N2 gas mixture dielectric barrier discharge (DBD) plasma. The broad 1H signals obtained even at 33 kHz spinning speed with spinning side bands indicates the existence of a large proton proportion in the film. The 1H and 13C signals are strongly broadened due to homo- and heteronuclear dipolar couplings and also due to amorphous nature of the deposited film. The local structure of the amorphous aH-CNx film is dominated by C–C and C–N single bonds i.e. carbon is mainly in the sp3 hybridized state. The Fourier Transform infrared (FTIR) spectroscopy of the film indicates the typical regions for –C≡N, –(CO), –NH, vibrations together with overlapping NH and OH stretching bonds. CH3 and C–N groups as well as species with CN conjugated double bonds are present in the deposited CNx film. From elemental analysis it is obtained that the composition of the film is (in wt.%): C: 61.8, H: 8.4, N: 17.7.