The results of the fabrication and characterization of silicon oxynitride films deposited by the plasma-enhanced chemical vapor deposition (PECVD) technique at low temperature and from N2, N2O and SiH 4 gaseous mixtures are reported herein. It is shown that high nitrogen concentration films with characteristics close to stoichiometric silicon nitride (Si3N4) can be obtained. In previous experiments utilizing N2O and SiH4 as precursor gases, it was demonstrated that precise control of the refractive index for silicon dioxide-like oxynitride SiOxNy (x+y=2) material in the 1.46 (SiO2) to 1.57 range can be attained. In this study, nitrogen gas (N2) was added to the previously studied gaseous mixture. In this way, it was possible to control the refractive index from 1.46 (SiO 2) to ∼ 2 (Si3N4) through the appropriate choice of the deposition parameters. The films were characterized by profilometry, ellipsometry, Rutherford backscattering spectroscopy (RBS) and Fourier transform infrared spectroscopy (FTIR). © 2003 Elsevier Inc. All rights reserved.