Electronic transport and optical properties of indium oxide thin films prepared by thermal oxidation

Indium oxide (In2O3) thin films were prepared using thermal oxidation of metallic films. Indium metallic thin films were deposited onto glass substrates, by vacuum thermal evaporation. Optical and electronic transport properties of thermally oxidized In2O3 films were investigated and these properties were correlated with their preparation conditions, more exactly with oxidation temperatures (Tox = 623 K, 673 K and 700 K, respectively). Structural analysis, investigated by X-ray diffraction and electron diffraction, reveals that the obtained films possess a polycrystalline structure. The temperature dependence of electrical conductivity was studied using surface-type cells with Ag electrodes. The electronic transport mechanism, in respective films, is discussed in terms of crystallite boundary trapping, proposed by Seto. Some characteristic parameters such as energy barrier, impurity concentration, distribution of interface states, were determined. Transmission and reflection spectra were recorded and by using the values of these coefficients, some optical parameters were calculated (absorption coefficient, optical band gap, refractive index).

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► By using a simple and low cost method, polycrystalline In2O3 films were obtained.
► Electronic transport mechanism is significantly influenced by grain boundaries.
► The optical parameters are strongly depending on the preparation conditions.