Study of structural and morphological properties of RF-sputtered SnO2 thin films and their effect on gas-sensing phenomenon

The present work focuses on understanding the impact of varying the thickness of SnO2 thin films on its gas-sensing response. Systematic studies were conducted by X-ray diffraction (XRD) and atomic force microscopy (AFM) on the structural and morphological properties of SnO2 thin films, which were thereafter correlated for a deeper understanding of the sensing phenomenon. The structural and morphological properties of SnO2 thin films were found to be highly dependent on the film thickness. The 90 nm SnO2 thin film exhibits the maximum sensing response to 200 ppm liquefied petroleum gas (LPG). A rough microstructure and the maximum surface-to-volume ratio of the 90 nm SnO2 thin film favors the gas-sensing response. It also possesses the smallest grain size, with the majority of crystallites oriented along the preferred (110) plane. The results suggest the possibility of utilizing the 90 nm SnO2 thin film as a base material, which can be further modified using a catalyst for the efficient detection of LPG gas in the future.