Multiscale Analysis and Morphology of TiC Films Deposited by Pulsed Laser Ablation

Abstract

In this work the microscopic morphology of titanium carbide thin films, obtained by pulsed laser ablation, are studied. A target of TiC has been ablated in vacuum with a laser Twinkle of Light Conversion Ltd. capable to furnish impulses of 250 fs, with a repetition frequency of 10 Hz at the wavelength of 527 nm. The ablated material has been deposited on (111) oriented silicon substrates, maintained at ambient temperature during the film deposition. Digital images of the films have been acquired through scanning electron microscopy. Numerical codes have been developed in Matlab environment, to obtain a three-dimensional reconstruction of the film surfaces starting from the bidimensional images. On such reconstruction a multi-scale analysis has been performed by hilbertian methods, for the characterization of the surface roughness and to study the distribution of the deposited nanoparticles. The results show that the free surface of the film has a characteristics scale invariance that allow the description by multi-fractal techniques. In particular the fractal dimension of the surface has been calculated in nanometric range. The investigation allows to identify some proper morphological indicators to characterize the film geometry and parameterize the tribological properties of the interface. These indicators, if opportunely employed together with classical methods of analysis, furnish a further tool for better understanding the complex nature of the deposits.