Istituto per la Microelettronica e Microsistemi     
Cappelli E., Orlando S., Servidori M., Scilletta C. Nano-graphene structures deposited by N-IR pulsed laser ablation of graphite on Si. In: Applied Surface Science, vol. 254 (4) pp. 1273 - 1278. Elsevier B.V, 2007.
Thin nano-structured carbon films have been deposited in vacuum by pulsed laser ablation, from a rotating polycrystalline graphite target, on Si (1 0 0) substrates, kept at temperatures ranging from RT to 800 degrees C. The laser ablation was performed by a Nd:YAG laser, operating in the near IR (lambda = 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) similar to 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 (similar to 400 degrees C), easy evolve toward more stable sp(2) aromatic bonds, in the plume direction. Increasing temperature th e 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.
DOI: 10.1016/j.apsusc.2007.09.098
Subject Oriented nano-graphene growth
Carbon films
Grazing incidence XRD
Film density
X-ray reflectivity

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