From Transparent Conducting Material to Gas-Sensing Application of SnO 2 :Sb Thin Films

Transparent conductive thin films of nanocrystalline tin oxide:antimony (SnO2:Sb) were deposited on a preheated glass substrate at 400°C via spray pyrolysis technique. The effects of Sb doping concentration on morphological, structural and optical properties of the films were investigated by ultraviolet (UV)-visible absorption, x-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The XRD study revealed that all the films had a polycrystalline nature, which increased with the Sb doping up to 4 wt.% and then decreased with further Sb doping. Similarly, the SEM images highlighted that the grain size of the SnO2:Sb thin films increased with Sb doping from 2 wt.% to 4 wt.% and then decreased for 6 wt.%. UV–visible study demonstrated that the average transmission in the visible region was found to vary from 35% to 75% depending on the Sb doping concentration. As a proof of concept, we implemented the SnO2:Sb thin films with different Sb doping for gas-sensing applications. To measure the selectivity of the SnO2:Sb thin films, the Sb-doped and -undoped films were exposed to different types of gases with varied concentration. The results of this work demonstrated that the SnO2:Sb thin film-based gas sensor had a high potential for NH3 at a low temperature (100°C). In addition, long-term stability of the SnO2:Sb thin film-based sensor was measured at 100 ppm NH3 for 90 days.