Thin nano-structured carbon films have been deposited in vacuum by pulsed laser ablation, from a rotating polycrystalline graphite target, on Si h1 0 0i substrates, kept at temperatures ranging from RT to 800 8C. The laser ablation was performed by a Nd:YAG laser, operating in the near IR (l = 1064 nm).
X-ray diffraction analysis, performed at grazing incidence angle, both in-plane (ip-gid) and out-of-plane (op-gid), has shown the growth of oriented nano-sized graphene particles, characterised by high inter-planar stacking distance (d c ห$ 0.39 nm), compared to graphite. The film structure and texturing are strongly related both to laser wavelength and substrate temperature: the low energy associated to the IR laser radiation (1.17 eV) generates activated carbon species of large dimensions that, also at low T ($400 8C), easy evolve toward more stable sp 2 aromatic bonds, in the plume direction. Increasing temperature the nano-structure formation increases, causing a further aggregation of aromatic planes, voids formation, and a related density (by X-ray reflectivity) drop to very low values. SEM and STM show for these samples a strongly increased macroscopic roughness. The whole process, mainly at higher temperatures, is characterised by a fast kinetic mode, far from equilibrium and without any structural or spatial rearrangement.