Characterization of CNx films deposited by pulsed laser ablation using spectroscopic ellipsometry

Amorphous carbon nitride (CNx) films were grown on silicon substrates by ArF laser ablation (PLD) of a graphite target in presence of nitrogen at various gas pressures. These films have been measured by spectroscopic ellipsometry in the UV–vis and IR wavelength range. In the UV–vis range, the optical indices of the CNx films have been extracted accurately using a model including surface roughness. The optical indices of the films are modelized by a Forouhi dispersion law model and the thickness and roughness are adjusted at the same time. The optical gap is extracted from the extinction coefficient. In the IR spectral range, the conductivity of the films is extracted from the Drude tale model. These structural and optical results are compared to the physico-chemical results provided by Rutherford backscattering (RBS) and elastic recoil detection analysis (ERDA).