Characterization of titanium dioxide films obtained with a vacuum arc

ARIEL KLEIMAN; DIEGO G LAMAS; ADRIANA MÁRQUEZ

Campinas

Encuentro; 20ª RAU - LNLS; 2010

The performance of TiO2 ¯lms applied in heterogeneous catalysis for the removal of contaminant or as sensor of oxidant gasses depend mainly on the crystallographic phases present in the ¯lm and on the surface morphology. Films obtained by vac- uum arc deposition (VAD) are attractive due to the high energy of the ions involved in this process and the high deposition rate. The ¯lms deposited with this method grow nano-structured and often show a structure with a preferential plane orien- tation. In this work a study of the crystalline structure and of the homogeneity, density and thickness of TiO2 ¯lms grown with VAD at di®erent conditions (sub- strate temperature, deposition time and number of discharges)on glass and silicon substrates is presented . The measurements were carried out at the XRD1 beam line of the LNLS using x-ray re°ectometry (XRR) and x-ray di®raction (XRD) with grazing incidence. The measured XRR patterns were ¯tted employing the Parrat formalism. In all XRR registers, independently of the sample deposition conditions, the interference fringes were clearly observed, this result indicates a high homogeneity of the ¯lms and a low roughness (lower than 10 nm). The ¯lm density values obtained from XRR agreed with the tabulated values for anatase and rutile TiO2 phases in accord with the structure determined from XRD. From XRR interference fringes ¯lm thickness from 70 to 300 nm were determined, by showing a good agreement with the thickness values estimated through transmit- tance measurements in the UV-visible range. These results were complemented by the analysis of the surfaces with an atomic force microscope.