Femtosecond pulsed laser ablation and deposition of titanium carbide

In this work we have evaporated a titanium carbide target by an Nd:glass laser with 250 fs pulse duration. The plasma produced from the ablation has been characterized by Intensified Coupled Charge Device (ICCD) fast imaging, optical emission spectroscopy and quadrupole mass spectrometry, while X-ray Diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDX), X-ray Photoelectron Spectroscopy (XPS) and Scanning and Transmission Electron Microscopy have been used to study the deposited film morphology and composition. The plume shape and front velocity are very similar to those found in other systems and are typical of femtosecond ablation. In particular the front velocity is 1.1×107 cm s-1 at a laser fluence of 1.9 J cm-2 , while the value of the cosine exponent is 4.5 in the same conditions. In the TiC system a delayed emission, found by ICCD imaging and emission spectroscopy, is also present. In fact, although the emission involved in the “traditional” plume ends after about 1 μs, the target is still hot and gives origin to another emission, expanding with a velocity that is about two orders of magnitude lower compared to that of the traditional plume (2.2×104 cm s-1 at a laser fluence of 1.9 J cm-2 ). The results of the analysis of both the gaseous plume and the deposited films seem to indicate that in the case of TiC system the presence of a large number of particles ejected from the target is responsible for the formation of the films. XPS and EDX data indicate that the stoichiometry of the target is preserved in the films, while XRD analysis shows that the films are amorphous in structure.