Synthesis and characterization of a-CNx thin films prepared by laser ablation

Amorphous carbon nitride (a-CNx) thin films were synthesized by laser ablation on silicon (100) and glass substrates. The plasma was produced using the fundamental line of a Nd:YAG laser with 28 ns pulse duration focused on a graphite target. Deposition of a-CN films was carried out in a nitrogen atmosphere in the range of pressures from 3 x 10 to 1.5 x 10 Torr. The laser fluences used in this work were varied from 9 to 46 J/cm. We have carried out the characterization of the optical properties, composition and morphology of the thin films as a function of the nitrogen pressure and the laser fluence used for deposition. The study of the optical properties showed that the optical band gap diminishes as the pressure is increased. The compositional characterization showed the presence of carbon, nitrogen and oxygen in the deposited films; the nitrogen content increased as the pressure increases reaching a value of 29% in atomic concentration at a pressure of 7.5 x 10 Torr. The surface morphology of the deposited films was characterized by a roughening of the surface as the pressure increases; it is observed also that the roughness diminished as the laser fluence increased.