Humidity sensing elements based on cerium doped titania-silica thin films prepared via a sol–gel method

• Humidity sensing elements are prepared by thin film deposition via a sol–gel method.
• The basic precursors for the thin film deposition are TBOT and PDTS.
• The obtained thin films are composed of Ce-doped Ti-Si oxides.
• The impact of the precursors’ proportion on the sensor properties is investigated.
• The change in resistance R of the samples reaches about four orders of magnitude.

This paper presents the studies of the characteristics and parameters of thin film humidity sensing elements, obtained by the deposition of Ti-Si-oxide films in the presence of a Ce-dopant via a sol–gel method using titanium (IV) n-butoxide and polydimethylsiloxane as basic precursors. The proportion between these precursors predetermines the mechanism of polymerization and subsequent gel-formation. As a result, this affects the structure and porosity of the obtained films after their sintering and also their response to humidity. The electrical characteristics of the respective samples were examined by an impedance analyzer. The sintered oxide films were observed by scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction analysis. The sensing elements obtained are distinguished for their high response to humidity and the variation in their resistance reaches up to four orders within the range of 15–93% relative humidity at 20 Hz and 25 °C.