Enhancement in the Sensing Efficacy of ZnO-based Ethanol Sensor: Fe-ZnO Film

Abstract

This study compares the gas sensing performance of the ZnO and 5 % Fe-doped ZnO (Fe-ZnO) films synthesized by a spin coating technique. The XRD analysis unveiled the polycrystalline nature of the initially prepared films, showing a decrease in crystallite size from 25.69 ± 0.95 nm for ZnO to 19.49 ± 0.72 nm for Fe-ZnO. Furthermore, the introduction of Fe into ZnO increased the band gap, with values shifting from 3.190 ± 0.105 eV for ZnO to 3.244 ± 0.147 eV for Fe-ZnO and decreased the grain sizes. The reduced grain sizes helped to increase the gas response of the ZnO film. The ethanol vapor sensing experiments performed at a broader temperature range of 100-300 ºC demonstrate that the best gas response of the Fe-ZnO film at 260 ºC is 17.8 ± 0.4 which was nearly 1.5 times greater than that of the ZnO film at the same temperature. Moreover, it's worth noting that the Fe-ZnO thin film exhibited quicker response and recovery in comparison to the ZnO thin film, with response and recovery times of 32 ± 2 and 162 ± 3 s, accordingly, for 40 ppm ethanol exposure. These findings contribute to a deeper understanding of gas sensing mechanisms in both ZnO and Fe-ZnO thin films which hold promise for future developments in gas sensor technology.