<title>Characterization of ablation plume during pulsed laser deposition of NbTex thin films</title>

Abstract

A large field of applications as microelectronics, micromechanics and optics needs to overcome the deposition of various materials showing dielectric, superconducting, piezoelecinc properties under thin film form. Numerous methods were developed as Chemical Vapour Deposition, Sputtering, Thermal Evaporation. Since the early 1980's, a new process based on laser ablation is developed.1 The Pulsed Laser Deposition (P.L.D) method is based on the laser evaporation of a target and the subsequent deposition of the ablation plume on a substrate (see fig. 1). A wide variety of materials was successfully deposited in thin film form by this method. Recently, Nb5Te4 thin films were realized for the first time by using P.L.D process.3 The Nb5Te4 compound presents strong anisotropic properties and finds applications in microelectronics (1D conductors) and micromechanics (solid lubricant). These first results3 shown the key roles played by the laser fluence and the substrate temperature on the film composition and crystallisation. For example, increasing the laser fluence decreases the interreticular distance observed by X-ray diffraction and increases the Te/Nb ratio. This shows the importance of kinetic parameters of the laser-induced plume on the crystallisation process. In order to understand the influence of the laser parameters on the film formation, it is necessary to study the ablation process and the expansion of the ablation cloud.