DC magnetron sputtering deposition of titanium oxide nanoparticles: Influence of temperature, pressure and deposition time on the deposited layer morphology, the wetting and optical surface properties

Titanium dioxide nanoparticles were prepared on glass substrates by reactive DC magnetron sputtering. As highlighted by the atomic force microscopy characterization, we were able to control the nanoparticles' surface coverage and diameter by varying the deposition time and the total pressure, respectively. The titanium dioxide energy band gap, determined by using ultraviolet-visible spectroscopy, depends on the total pressure but is quite independent on the deposition temperature. On the contrary, it is blue shifted when the pressure increases. Finally, the contact angles slightly decrease after ultraviolet illumination irrespective of the different deposition parameters, indicating an improvement of the hydrophilic properties of the adsorbed layer. After 21 h in dark, the contact angles are nearly identical to the ones before exposure to UV light: the samples do not keep their hydrophilic behaviour.