The effect of bombarding conditions on the properties of multifunctional Ti–C–O thin films grown by magnetron sputtering

Reactive sputtered titanium oxide and titanium carbide thin films have been extensively investigated because of their remarkable optical, electrical, mechanical and chemical properties. The possibility to join both materials appears to be an important issue in order to find new and multifunctional applications for a combined material: titanium oxycarbide, TiCxOy. Taking this into account, the main purpose of this work consists in the study of the effect of the ion bombardment on the properties of multifunctional Ti–C–O thin films, grown by reactive magnetron sputtering. The depositions were carried out from a Ti target with incrusted C pieces, varying the bias voltage from grounded condition up to − 150 V. The oxygen flow rate was kept constant at 4 sccm. The obtained results show that the composition of the films presented some variations, revealing some preferential re-sputtering of carbon. X-ray diffraction results showed a progressive amorphization of the samples with increasing negative bias voltages, which is result of the formation of an oxide phase. Raman results reveal the presence of these oxide phases as well as the presence of D and G modes characteristic of amorphous carbon materials. This amorphization also resulted in an increase in electrical resistivity of the samples. Mechanical behaviour characterization showed an increase in hardness when preparing the films with a negative bias voltage. Grounded sample has a hardness value of about 17 GPa, while negative biased samples revealed hardness values around 20 GPa.