Density and Young’s modulus of thin TiO2 films

Densities, ρ, of thin TiO2 layers, produced by reactive evaporation (RE) and ion plating (IP) have been analyzed by means of grazing incidence X-ray reflectometry (GIXR). Depending on the deposition conditions, the layers are amorphous or polycrystalline, with densities between 2.9 g/cm3 and 3.9 g/cm3. Young’s moduli, E, have been analyzed for 280 nm and 500 nm thick layers by means of surface acoustic wave spectroscopy (SAWS) and vary between 65 GPa for RE films and 147 GPa for IP layers. The values are independent of film thickness, but correlate with the density. A phase transition of the TiO2 films from the amorphous state to anatase occurs at temperatures above 210°C and increases the Young’s modulus significantly, whereas the density remains unchanged.