Effect of thickness on the physical properties and gas sensing application: anatase titanium dioxide nanofilms by automated nebulizer spray pyrolysis (ANSP)

In this work, effects of thickness towards volume proportion of TiO2 nanofilms were deposited on a glass substrate at 500 °C by using ANSP method. The optical profilometer shows the coated films thicknesses were increased (186, 234, 311, 397 and 433 nm) by increasing the volume proportion. Based on the thickness, The XRD reveals a polycrystalline tetragonal anatase phase with decreased particle sizes. The topographical study (AFM) of 3D surface view shows the incremented average roughness (Ra) values. The surface morphological variations with decremented particle size were examined by FESEM. The maximum transmittance ~78.5% (λ = 612.8 nm) is obtained to 186 nm thickness and further increment of thickness shows the decremented value of transmittance with an absorption edge shifted from lower to higher wavelength (blue shift) and the calculated band gap value Eg = 3.65–3.26 eV. The gas sensing performances of films was studied by using a various sensing parameters, obviously C2H6O gas shows highest response (Sm = 13% as 397 nm) at 300 °C for 150 ppm gas concentration against other gasses (NH3, CH4O, C3H8O and C3H6O).