Carbon nitride films by RF plasma assisted PLD. Spectroscopic and electronic characterization

This research was mainly devoted to characterise thin films of carbon nitride (CN) grown by Pulsed Laser Deposition in specific conditions. We introduced a Radio Frequency (RF) system to generate plasma of Nitrogen, in the close proximity of the Silicon substrate, crossing the carbon plume coming from the ablated graphite target, so as to increase the reactivity of the species and the probability of generating carbon nitride films. By XPS, Raman and OES (optical emission spectroscopy) we compared two samples grown by expanding the Carbon plume a) in pure Nitrogen and b) with the plasma activation of Nitrogen. We verified a sensible increase in activation and reactivity of nitrogen, resulting in CN formation, when using plasma confined near the substrate by a negative biased ring. We performed also some measurements of surface conductivity by the four point probe method and verified a different behaviour of the samples: an almost graphitic behaviour for the sample grown with N2 atmosphere and a more insulating nature for the sample grown with plasma, owing to an increased incorporation of nitrogen.