Fabrication of nanogranular TiO₂ thin films by SILAR technique: Application for NO₂ gas sensor

The present investigation reports on the Nitrogen dioxide (NO₂) gas sensing properties of the nanogrannular Titanium dioxide (TiO₂) thin films synthesized on a glass substrate using simplistic successive ionic layer adsorption and reaction (SILAR) technique at room temperature. The deposition of TiO₂ thin films was carried out by varying the SILAR reaction cycles. The synthesized TiO₂ thin films showed a granular morphology of size 50–100 nm with an orthorhombic structure. The photoluminescence spectra of nanogranular TiO₂ thin films exhibits absorption band edge in the visible region (∼442 nm). The gas sensing performance are evaluated as a function of nanogranular size of TiO₂, the operating temperature, response and recovery time and sensitivity of NO₂ gas from 50 to 200 ppm. A high response towards NO₂ has been obtained at an operating temperature of 250 ⁰C. Moreover, the nanogranular TiO₂ thin films based gas sensor shows better gas sensitivity towards NO₂ gas at 50 ppm with good selectivity.