Pulsed laser growth and characterization of thin films on titanium substrates

Colored layers were obtained by laser surface treatment of Ti substrates with a pulsed Nd:YAG Q-switched laser. The changes in the morphology, structure and chemical composition of the layers were studied by SEM, EDS, XPS, SIMS and Raman spectroscopy as a function of the laser fluence in the 4–60 J cm 2. For laser fluences lower than 25 J cm 2, the layers are colorless or yellow. Their surface is smooth, but they display cracks which increase when the fluence increases. The O/Ti ratio, determined by XPS analysis, varies from 0.7 (colorless layers) to 1.3 (yellow layer). Moreover, XPS spectra evidence non-negligible amounts of nitrogen and carbon in these layers. Raman spectra show large bands which support the formation of titanium oxy-carbo-nitride. For laser fluences higher than 25 J cm 2, the layers are purple and blue and very rough sample surfaces were obtained. As a consequence of this, XPS analysis could not be used to obtain quantitative information on the layer composition. Finally, Raman spectra clearly showed the increasing formation of anatase and rutile phases of TiO2 in these layers when the laser fluence increases