Synthesis of carbon nitride films by direct current plasma assisted pulsed laser deposition

Carbon nitride films were deposited by pulsed laser ablation of a graphite target under a nitrogen atmosphere at room temperature. A direct current discharge apparatus was used to supply active nitrogen species during the deposition of carbon nitride films. The composition and bonding structure of carbon nitride films were determined by Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy. The incorporation of nitrogen atoms in the films is greatly improved by the using of a dc glow discharge. The ratio N/C can reach 0.34 at the discharge voltage of 400 V. Six peaks centered at 1025 cm(-1), 1226 cm(-1), 1381 cm(-1), 1534 cm(-1), 1629 cm(-1), and 2200 cm(-1) can be clearly distinguished from the FTIR spectra of the deposited films, which indicates the existence of C-N, C=N, and Cequivalent toN bonds. The fraction of sp(2) C, Cequivalent toN bonds, and C=N bonds in the deposited films increases with increasing discharge voltage. Deconvolution results of C1s and N1s spectra also indicate that nitrogen atoms in the films are chemically bonded to sp(1) C, sp(2) C, and sp(3) C atoms. Most of the nitrogen atoms are bonded to sp(2) C atoms. Increasing the discharge voltage leads to a decrease of the fraction of nitrogen atoms bonded to sp(2) C and the fraction of amorphous carbon; however, it leads to an increase of the fraction of nitrogen atoms bonded to sp(3) C and the fraction of sp(2) C and sp(3) C atoms bonded to nitrogen atoms.