Study of physical properties for In₂O₃ thin films produced by thermal oxidation as CO₂, H₂ gas sensor

Abstract

Polycrystalline In₂O₃ thin films have been prepared by using thermal oxidation method. The pure In metal was evaporated by using melbedume boat at vacuum 10^-6 torr on glass substrate. Thin films of thicknesses about 350 nm were prepared, after that we treated these films with two different temperatures and obtained In₂O₃ thin films in the presence of O₂. The X-ray Diffraction (XRD) results refer to polycrystalline phase. Scanning Electron Microscopy (SEM) was used to study the local morphology and the surface of In₂O₃ thin films obtained by thermal oxidation method. SEM shows high homogenous morphology. AFM results show 45 nm typical sizes for the grains. The optical properties were studied by using the UV-vis spectra then the energy gap was calculated from it. The values of energy gap E_g for In₂O₃ which were obtained from heat treatment to In metallic at 200 and 300°C are 3.5 and 3.1 eV, respectively.

Keywords: Indium oxide, thermal oxidation, x-ray diffraction, scanning electron microscopy, AFM analysis.