Effect of Post-Deposition Annealing Treatment on the Structural, Optical and Gas Sensing Properties of TiO₂ Thin Films

Abstract

One of the potential applications of TiO2 is its use in gas sensor technology. The aim of this work was to study the gas sensing properties of TiO2 thin films in combination with the effect of post-deposition annealing treatment. Titanium dioxide thin films with thickness 100 nm were prepared by the reactive dc magnetron sputtering. The thin films were deposited on sapphire substrate from a titanium target in an oxygen atmosphere. The samples were then post-annealed in air in the temperature range 600 °C 1000 °C. Crystal structure, surface topography and absorption edge of the thin films have been studied by X-ray Diffraction technique, Atomic Force Microscopy and UV-VIS Spectroscopy. It was found that the phase gradually changed from anatase to rutile, the grain size and roughness tended to increase with increasing post-annealing temperature. The effect of these factors on gas sensing properties was discussed. For electrical measurements comb-like Pt electrodes were prepared by standard photolithography and the films were exposed to different concentrations of H2 gas up to 10000 ppm in synthetic air at various operating temperatures from 200 °C to 350 °C.

Nanotubular Cr-doped TiO 2 for use as high-temperature NO 2 gas sensor

“…This potential barrier arises due to trapping of electrons by pre-adsorbed oxygen and subsequently developing a depletion region on the surface [35,36]. This is noticeable in our measurement that Cr-doped TiO 2 NTs showed higher values of resistance R=≈800 MΩ than R=≈5 kΩ of un-doped TiO 2 NTs at 500 °C.…”

Investigating the influence of Al-doping and background humidity on NO<sub>2</sub> sensing characteristics of magnetron-sputtered SnO<sub>2</sub> sensors

“…(2), causes some release of the captured electrons back to the metal-oxide surface resulting in a decrease of the upward band bending and ultimately a decrease in the resistance (Batzill, 2006;Haidry et al, 2012b). This is valid also for reducing gases (see e.g., Fig.…”

P2.0.5 Studies of Hydrogen Gas Sensing Properties of Anatase TiO2 Thin Films Prepared by Magnetron Sputtering

“…In our previous works [2,3], we have reported that the annealing temperature at which the phase transitionfrom Anatase to Rutile for TiO 2 thin films prepared in our laboratory by dc magnetron sputtering methodtook place was 700 °C -800 °C. In this work we limited our research to only anatase thin films annealed up to 800 °C.…”

“…In the present work, TiO 2 thin films were prepared by reactive dc magnetron sputtering method from Ti target [2,3]. The thickness of the thin films was determined from SEM image in cross-section to be 100 nm.…”

“…Thin films and nanostructures based on titanium dioxide are extensively studied for various applications because of their multifunctional nature. Among MOS (metal oxide semiconductors), the stability of titanium dioxide in harsh environment makes it a good candidate for gas sensing applications [1], which have been already reported many times in last decades [2,3,4,5]. Despite having excellent sensing properties and high stability, MOS gas sensors have problems with selectivity and are usually more suitable for higher operating temperature sensing applications i.e.…”