Metal organic CVD of nanostructured composite TiO2-Pt thin films: A kinetic approach

Nanostructured composite TiO2-Pt thin films at different Pt/Ti ratios were obtained by chemical vapor deposition (CVD) using titanium tetraisopropoxid e (TTIP) and platinum bisacetylacetonate (Pt(acac)(2)) as precursors in the presence of oxygen. The single growth process was kinetically controlled f or TiO2 and diffusion limited for Pt under the same experimental conditions . Co-deposition (growth temperature 673 K, total pressure 80 Pa) did not ch ange the individual growth kinetics, in the sense that the sum of the two d istinct growth models developed respectively for TiO2 and Pt fitted the exp erimental co-deposition results quite closely The platinum incorporation wa s well reproducible and the atomic Pt/Ti ratio in the films was varied in t he range 1:1 to 1:20 by changing the evaporation rates of the precursors. T he obtained composite films are biphasic and nanostructured with a regular, smooth surface. The time dependence of the platinum bis(acetylacetonate) s ublimation rate can give rise to a gradient of Pt concentration into the fi lm, which can be properly modulated for specific applications.