Substrate temperature dependent ammonia gas sensing performance of zinc ferrite thin films prepared by spray pyrolysis technique

Ammonia (NH3) production, storage, and transportation are prone to leaks, and exposure to NH3 levels above the Occupational Safety and Health Administration (OSHA) limit can affect the environment and be hazardous to human life. It is crucial to eliminate health risks by detecting NH3 within the exposure limit. In this work, thin films of zinc ferrite (ZF) having the morphology of nanorods with laminated cubes and rectangular grains with laminated sheets were deposited using spray pyrolysis approach at various substrate temperatures (225–300 °C). Then employed the grown films to detect harmful NH3 gas below the OSHA exposure limit at room temperature. In this study, it was noted that the substrate temperature has a significant impact on the performance of the proposed sensor. Among the four temperatures, a good sensing response of S = 1.91 towards 25 ppm of NH3 was obtained for the film deposited at 225 °C. The enhancement was mainly due to the formation of films with a large surface-to-volume ratio and surface roughness with a tiny nanorod structure. For stability checking, the response of the sensor was recorded after 90 days towards 25 ppm of NH3. The results of stability also indicate that coated ZF225 film is an effective NH3 gas sensor. This research reveals that ZF thin films can efficiently detect the presence of NH3 in the environment.