Donated free electrons induced enhancement in the NH3 sensing ability of ZnO thin films - Effect of terbium loading

Abstract The hypothesis of this study is that the chemi-resistive vapor sensing ability of zinc oxide (ZnO) can be enhanced by adding suitable rare earth metal as a dopant to ZnO. To realize this hypothesis, different proportions of terbium (Tb) were added (1, 3 and 5 wt%) to the precursor solution and three respective sets of ZnO:Tb sensors were prepared in thin film form using nebulizer spray technique. Ammonia (NH3) vapor sensing properties like sensing response, response/recovery time, selectivity, repeatability and stability of the prepared ZnO:Tb thin films were investigated and compared with those of their undoped counterpart. The obtained results were correlated with their structural, optical, surface morphological and photoluminescence (PL) properties studied using X-Ray Diffractometry (XRD), UV–vis NIR spectrophotometry, Atomic Force Microscopy (AFM) and photoluminescence spectroscopy.