Structural and electrochemical properties of high quality epitaxial titanium carbide thin films grown by pulsed laser deposition on MgO (111) and Al2O3 (001) substrates
Résumé
The electrochemical behaviour of titanium carbide (TiCx, with 0.5 < x < 1) thin films is presented and discussed with respect to their structural properties. Epitaxial (111)-oriented TiC films are grown onto (111)-cut MgO and (001)-cut Al2O3 substrates by using TiC targets with various stoichiometry. When using a TiC target, the films grown on Al2O3 substrates exhibit cyclic voltammograms significantly different from those grown on MgO. As a matter of fact, their electrochemical properties are strikingly similar to films with TiC0.55 composition. It is demonstrated, by using high-resolution X-ray diffraction, that films grown on sapphire have a composition close to TiC0.55, the driving force for carbon deficiency being the relaxation of the compressive interfacial strain at the Al2O3/TiC interface. On the contrary, the interfacial strain at the MgO/TiC interface is tensile which cannot be compensated by variations in the Ti/C ratio.
Domaines
Matériaux
Origine : Fichiers produits par l'(les) auteur(s)