Effect of pyrolytic temperature on the properties of TiO2/ITO films for hydrogen sensing

• Promoting effect of ITO seeding layer resulted in c-axis oriented anatase TiO2.
• Optical spectra revealed both direct and indirect transition.
• Hydrogen sensing response of the film increased with substrate temperature.
• Recovery is faster depending on crystallinity of the film.

Titanium dioxide (TiO2) thin films were prepared on ITO (2 2 2) coated glass substrates by spray pyrolysis technique. The influence of substrate temperature on the orientation, phase, vibrational bands and band gap energy of TiO2 films were discussed. The X-ray diffraction patterns of the films revealed preferentially oriented (1 0 1) TiO2 anatase phase at the substrate temperature of 300 °C and 350 °C. Fourier transform infrared spectra of the films showed the significant sharpening of absorption band at ∼645 cm−1 with increase in substrate temperature, which clearly indicates the formation of anatase phase dependent on substrate temperature. Fourier Raman Spectra of the films showed the significant presence of long range order anatase TiO2 phase. The optical measurements of the film prepared at different substrate temperatures revealed the direct band gap of 3.15–3.63 eV and indirect band gap of 3.48–3.73 eV, characteristic of TiO2 anatase phase. To understand the enhancement of sensing performances of TiO2 films with substrate temperature, the gas sensing mechanism of the films towards 400 sccm of hydrogen at room temperature was studied and discussed.

Figure optionsDownload as PowerPoint slide