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 r eactive pulsed laser deposition (RPLD) from a Ti target in low-pressur e methane. We show that the small particulates having diameters smalle r than 0.5 mu m have a composition and a morphology identical to that of the deposited films which consist of pure, stoichiometric, cubic Ti C with a lattice parameter of 0.436 nm. In contrast, the larger partic ulates with diameters up to 3 mu m are a mixture of TiC and prevalent unreacted Ti. All particulates seem to have a spherical geometrical sh ape at the moment of their impact onto the collector. We consider that this feature is congruent with the formation of particulates by expul sion in a liquid phase from the melted layer existing inside the crate r forming on the target's surface under the action of the pulsed laser irradiation.