About the Nature of Particulates Covering the Surface of Thin Films Obtained by Reactive Pulsed Laser Deposition

We report new results concerning the composition and the structure of the particulates covering the surface of the thin films deposited by reactive pulsed laser deposition (RPLD) from a Ti target in low-pressure methane. We show that the small particulates having diameters smaller than 0.5 mu m have a composition and a morphology identical to that of the deposited films which consist of pure, stoichiometric, cubic TiC with a lattice parameter of 0.436 nm. In contrast, the larger particulates with diameters up to 3 mu m are a mixture of TiC and prevalent unreacted Ti. All particulates seem to have a spherical geometrical shape at the moment of their impact onto the collector. We consider that this feature is congruent with the formation of particulates by expulsion in a liquid phase from the melted layer existing inside the crater forming on the target's surface under the action of the pulsed laser irradiation.