FTIR reflectance spectroscopy of SiCXNYOZ(H) ceramic coatings: Structure interpretation by optical modelling

SiCXNYOZ(H) ceramic coatings have been deposited on steel substrate by plasma enhanced chemical vapor deposition (PE-CVD) using hexamethyldisilazane as precursor. The influence of the discharge power (3–90 W) on the network structure and optical properties of the amorphous coatings are discussed. The dielectric function of the layer which has been described by a set of Lorentzian oscillators have been determined from off-normal polarized FTIR reflectance spectra. The calculated spectra are fitted to the experimental measurements by variations of oscillator parameters and layer thickness. Based on dielectric functions the assignment of functional groups and the change of their concentration with deposition discharge power has been derived. A direct dependence of the intensity of the hydrogen modes and the layer thickness on discharge power has been found. An unambiguous influence of the discharge power on lattice modes was not detected.