High response chemiresistive room temperature ammonia gas sensor based on La-doped ZnO samples

Abstract

The current study describes the excellent sensing properties of zinc oxide samples with varying La doping concentrations (1, 3, and 5%). The X-ray diffraction (XRD) study suggests that the produced ZnO samples exhibit hexagonal structure. Due to varying concentrations of La, a notable difference in the morphological image of the samples was observed using a Field Emission Scanning Electron Microscope (FESEM). The existence of La, Zn, and O elements in the sample was analyzed by Energy Dispersive X-Ray Analysis (EDX). The Fourier Transform Infrared Spectroscopy (FTIR) studies validate the sample’s structure and functional group. The UV–Vis results showed that the maximum optical reflectance of 90% was attained in the visible region and the obtained band gap values for the samples were in the range of 3.27–3.33 eV. At ambient temperature, the La-doped samples demonstrated high sensitivity towards NH3 and had the highest response value of 1940% for the 250 ppm. According to the results, an excellent operating stability, and response/recovery time were obtained for the ZnO:La1% sample which suggests that the sample can serve as the most appropriate metal oxide for the detection of NH3 at room temperature.