Sustainable behavior of cauliflower like morphology of Y-doped ZnO:CdO nanocomposite thin films for CO2 gas sensing application at low operating temperature

Abstract

Yttrium doped ZnO:CdO (YZC) nanocomposite thin films with 0, 0.5, 1, 1.5 at% doping of Y (coded as YZC1, YZC2, YZC3, and YZC4) were deposited on the glass substrate by using sol-gel spin coating method and examined for CO2 gas sensing. The as prepared thin film samples were characterized for structural, surface and optical properties by X-ray diffraction (XRD), field emission electron microscopy (FE-SEM), and UV–Vis spectroscopy, respectively. The XRD pattern revealed that all thin films have polycrystalline nature including the combination of cubic (CdO) and wurtzite (ZnO) structure concurrently. The FE-SEM image indicated that the sample YZC2 shows the cauliflower like morphology and found suitable for gas sensing application. The optical bandgap energy was varied from 2.44 eV to 2.98 eV as the doping level of Y in ZnO:CdO was changed. The I–V characteristics were measured by two probe electrometers at room temperature and the highest conductivity was found 54.5 Ω−1 m−1 for YZC2 sample. The highest sensor response was 9 while response and recovery times were 4 s and 2 s, respectively at room temperature (27 °C) for YZC2 sample. Thus, the combinations of rare earth metal with metal oxide semiconductor (MOS) for YZC2 sample are suitable for CO2 gas sensing at room temperature.