Influence of Sb doping on the structural, optical, electrical and acetone sensing properties of In2O3 thin films

Indium oxide thin films (undoped and Sb doped) have been grown by a chemical spray pyrolysis technique on glass substrates using indium nitrate and antimony trichloride as the host and dopant precursors respectively and deionsied water as the solvent. In addition to studying the acetone sensing properties, the effect of Sb doping on the structural, optical, and electrical properties of In2O3 thin film has been investigated. X-ray diffraction analyses reveal that the films are polycrystalline in nature, possess cubic structure, and have crystallite sizes in the range 8–15 nm. The Sb-doped films have reduced crystallinity and crystallite size as compared to the undoped In2O3 film. A change in the optical transmittance in the visible region as well as the value of optical band gap is observed upon Sb doping. Further, the incorporation of Sb to In2O3 also alters the value of electrical resistivity over a wide range of temperature. The gas sensing properties of the films have been investigated for various concentrations of acetone in air at different operating temperatures. Among all the four films examined, the 1.5 at.% Sb-doped In2O3 thin film shows the highest optical transmittance in the visible region, the least electrical resistivity at room temperature and the highest response (~95%) for acetone vapor at an operating temperature of 300 °C and a concentration of 80 ppm in air.