Correlation between plasma characterization and growth of fullerene-like CNx thin films deposited by pulsed laser ablation

Fullerene-like amorphous carbon nitride (CNx) thin films were synthesized by pulsed laser ablation (PLA) of pyrolytic graphite (99.99%) target in nitrogen using a Nd:YAG (Neodimium Doped Yttrium Aluminum Garnet) -pulsed laser. The films were deposited onto silicon substrates at 300 °C in nitrogen atmosphere within the 0.7–13.0 Pa pressures. The composition and structure of these films were analyzed by means of reflection absorption infrared spectroscopy (RAIRS), X-ray photoemission spectroscopy (XPS), and Raman spectroscopy and the morphology of the films surfaces by atomic force microscopy (AFM). The XPS study of the N 1s bonding energy region provided typical spectra of the CNx materials. The spectra present the energy peaks at 400.8 (P2) and 398.4 (P3) eV. In our conditions for films deposited at 0.7 Pa, the P2/P3 ratio is 1.4, indicating a fullerene-like structure. Raman analysis of films produced at different pressures shows the characteristic D and G peaks at 1360–1370 and 1580–1590 cm−1 relate to the bond length in sp3 or sp2 coordinated carbon, respectively. The optical emission spectra (OES) from the PLA–plume allowed to correlate the concentration and vibrational temperatures of CN and C2 species present in the plasma with the fullerene-like CNx film composition and bonding determined by XPS, IR, and Raman spectroscopy.