Microwave Plasma Process for SiCN:H Thin Films Synthesis with Composition Varying from SiC:H to SiN:H in H 2 /N 2 /Ar/Hexamethyldisilazane Gas Mixture

SiC x N y :H thin films are obtained with the microwave plasma assisted chemical vapour deposition (MPACVD) method in the gas mixture H 2 /Ar/Hexamethyldisilazane. When very few amounts of nitrogen are added to the gas mixture, the film composition changes drastically from SiC x :H like films to SiN x :H like films, according to X‐rays Photoelectron Spectroscopy and Fourier Transform Infra‐Red Spectroscopy (FTIR) analysis. The refractive index ( n ) and Tauc's optical gap ( E g ) are modified over a wide range of values (1.75 ≤  n  ≤ 2.15 and 3.5 eV ≤  E g  ≤ 5 eV) with nitrogen addition to the feed gas leading to thin films optical constants close to those of SiC or Si 3 N 4 . Therefore, for the films obtained without nitrogen, SiC nanoparticles with a size of about 20 nm embedded in an amorphous SiCN:H matrix are synthesized, leading to nanocomposite films.