Thickness effect of ZnO/PPC gas sensor on the sensing properties of NO₂ gas

In this work, ZnO nanostructure thin films were deposited with two different thicknesses (300 and 600 nm) on Poly Propylene Carbonate (PPC) substrates by using RF Magnetron sputtering technique in order to fabricate ZnO gas sensor for NO₂ gas. The structural and morphological properties of the deposited films were studied by X-ray diffraction (XRD) and Atomic Force Microscopy (AFM). XRD spectra of the films showed mainly the ZnO (002) diffraction peaks at 2θ = 34.35° and 34.25° with full width at half maximum (FWHM) of 0.44° and 0.34°, respectively. AFM images showed that the minimum grain size of the films was 78.98 nm and 92.44 nm for thicknesses of 300 and 600 nm respectively. It was found that the maximum sensitivity value for NO₂ gas was about 63% and 42% for 300 nm and 600 nm thickness, respectively.