J.M. Chappé, A.C. Fernandes, C. Moura, E. Alves, N. P. Barradas, N. Martin, J.P. Espinós, F. Vaz
Surface and Coatings Technology, 206 (2012) 2525-2534
Reactive magnetron sputtering was used to deposit titanium oxycarbide thin films. The overall set of results showed that the oxygen flow rate, and thus the composition of the atmosphere in the deposition chamber, controls the composition of the titanium oxycarbide thin films obtained by reactive sputtering. Rutherford Backscattering Spectroscopy analysis revealed the existence of three major types of films, indexed to their particular composition ratios. A detailed study by X-ray photoelectron spectroscopy was carried out in order to characterize the evolution of the TiC, CO and CC bonds induced by the increase of the oxygen partial pressure, which was found to be closely related with the different zones of composition that were suggested. Micro-Raman spectroscopy and X-ray diffraction measurements allowed describing the complex nature of the film structure, namely in what concerns different phases and their evolution, texture phenomena and grain size evolution as a function of the particular composition and film types (different zones). Electrical conductivity revealed a transition from a metallic to a semi-conducting behavior as a function of the oxygen concentration in the films, in good agreement with the different zones that were suggested. Similarly, optical properties supported this gradual change and for oxygen contents higher than 67 at.%, the films exhibited typical reflectance of insulator materials (interferences) in the UV, visible and near IR regions.