Effects of deposition parameters on the properties of amorphous carbon nitride thin films prepared by laser ablation

Abstract

The properties of amorphous carbon nitride thin films, such as the composition, density, optical band gap, microstructure (sp3/sp 2 ratio), have been investigated as a function of the working gas pressure and the laser fluence used for deposition by pulsed laser ablation. The compositional characterization showed the presence of carbon, nitrogen, oxygen and hydrogen in the deposited films; the nitrogen content increased as the fluence increased reaching a maximum saturation value of 30.0 at. % at a nitrogen pressure of 7.5 × 10-2 Torr. A similar behavior was observed when the fluence was kept constant and the gas working pressure was varied. The study of the optical properties showed that the optical band gap increased as the pressure and fluence were increased. The density of the deposits diminished as the nitrogen content increased suggesting the formation of a more porous material at higher N contents. The Raman results revealed that the ID/IG ratio increased monotonically with the increase of nitrogen content in the films indicating a rise in either the number or the size of the sp2 clusters. © 2007 IOP Publishing Ltd.