CO gas sensing characteristics of BaSnO3 epitaxial films prepared by PLD: The effect of film thickness

Abstract

In the present work, perovskite Barium Stannate (BaSnO3) thin films of varying thickness were investigated for carbon monoxide (CO) gas sensing application. Epitaxial BaSnO3 thin films of thickness (90, 270 and 360 nm) were grown on MgO substrates by using pulsed laser deposition technique. The enhanced electrical properties of the films with decreasing thickness can be attributed to the increased amount of Sn4+ ions in the film. An increase in CO gas sensing response of thin films was observed with decreasing film thickness. BaSnO3 thin film having 90 nm thickness exhibits a higher gas sensing response of 58% at 400 °C, which is a quite lower temperature as compared to the previous works in similar systems. This high value is attributed to the presence of large number of grains and grain boundaries providing easy adsorption and desorption of oxygen species at the surface, confirmed by the atomic force microscopy and X-ray photoelectron spectroscopy, respectively.