Effects of the plasma expansion dynamics and of the laser fluence on CNx thin films deposited by laser ablation

Carbon nitride thin films have been deposited by pulsed laser ablation of graphite targets in a controlled nitrogen/argon atmosphere. The experiments were performed by irradiating the targets with the output of a KrF laser at two different laser fluences and both in a plasma regime of free expansion and of shock wave formation. The sample compositions were determined by means of X-ray photoelectron spectroscopy. A study of the C1s and N1s core level photoemission bands evidenced nitrogen atomic contents up to 26%, with respect to carbon. Raman and XPS spectroscopy results clearly indicate that there is a strong correlation between the plasma expansion dynamics and the laser fluence with the structural properties of the deposited thin films.