ZnO wrinkled nanostructures: enhanced BTX sensing

Zinc oxide nanostructured thin films were deposited at different substrate temperatures on a glass substrate with spray pyrolysis method. The effect of substrate temperature on microstructural, morphological, optical properties of the thin films has been studied systematically using X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy, scanning electron microscopy (SEM) and UV–Vis spectroscopy. The XRD pattern shows polycrystalline nature and films were crystallized in the wurtzite phase type. Electron–phonon-coupling in zinc oxide thin films was analyzed by Raman spectra at room temperature. SEM micrographs depicted that the substrate temperature influenced the growth of the thin films. Root-mean-square roughness of the thin films was measured using atomic force microscopy. The optical spectra of the ZnO thin films measured in the UV–Vis range. As the substrate temperature increased from 275 to 425 °C, optical band gap was found to decrease from 3.10 to 2.96 eV. Sensitivity and selectivity of the samples were tested at room temperature with respect to different volatile organic gases like benzene, toluene and xylene. Recovery and response times were determined using transient response curve with xylene as the test gas.