Amorphous SiC and SiCxNy films have been deposited by pulsed laser deposition on single crystal silicon substrates by KrF (248 nm) excimer laser ablation of a SiC sintered target in a vacuum system at room temperature using nonreactive, Ar, and reactive, N2, background gases at different pressures. The pressure range in the growth chamber was from 4×10−8 Torr to 80 mTorr. The optical properties and stoichiometry of films were varied by the introduction of a background gas. The resulting films are inspected by spectroellipsometry in the photon-energy range of 1.5<hv<5.0 eV. In situ high resolution x-ray photoemission spectroscopy characterization was performed on every film to obtain the atomic concentration and bonding constitution of the elements as a function of background gas pressure. The ideal stoichiometry for SiC films was obtained at Ar pressures higher than 30 mT. The existence of a new phase, given by SiCN2, was suggested from surface techniques and ellipsometric data in the deposition of SiCxNy films at N2 pressures higher than 30 mTorr.