Sol-gel assisted nano-structured SnO2 sensor for low concentration ammonia detection at room temperature

Abstract

SnO2 nanostructured thin film based gas sensor is fabricated by sol-gel spin coating technique. The performance of the fabricated sensor has been investigated for analytes viz. ammonia (NH3) solution, acetone (C3H6O), methanol (CH3OH) and 2-propanol (C3H8O) at room temperature (RT) with humidity level ∼55% RH for concentration range 500 ppb-500 ppm. High response and good selectivity towards ammonia are observed with very fast response and recovery time at RT, for extreme low concentrations. Upon exposure to 500 ppb and 1 ppm of NH3, sensor manifests appreciable response ∼28% and ∼31.5%, respectively. High response of the sensor at RT is attributed due to porous nanograins (with average particle size ∼50 nm) based SnO2 thin film layer. Nanograins structure is obtained due to addition of glycerine in the sol solution, which also leads to porosity enhancement of the sensing layer. Good reproducibility and appreciable immunity to drift behavior are other attributes of the fabricated device. X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and scanning electron microscopy (SEM) results are used to study the structural, chemical composition, topography and morphological characteristics of the prepared SnO2 thin film, respectively.