Highly textured ZnO thin films grown using sol-gel route for gas sensing application

The crystalline orientation of metal oxide thin films often modulates their structural, optical as well as surface related properties. Viewing in the same line, in the present work we have systematically investigated the structural, micro structural, optical and gas sensing characteristics of highly textured zinc oxide (ZnO) thin films oriented along (002) crystalline planes. The ZnO thin films have been grown on quartz substrates by spin coating the precursor sol prepared through cost effective wet chemical synthesis route. The structural and micro structural characteristics of the grown films are studied using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) respectively. The optical properties of the synthesized films are investigated by analyzing the ultraviolet-visible (UV–VIS) and photoluminescence (PL) spectroscopy. From the recorded absorption spectra band gap energies of the films are estimated. The gas sensing characteristics of the grown films are investigated upon exposure to various toxic and combustible gases at different operating temperatures. Finally, the effect of crystalline orientation on the structural and optical properties and gas sensing characteristics of the grown ZnO thin films are explored.