Sol-gel growth and characterization of In2O3 thin films

Indium oxide as thin film and powder was prepared by the sol-gel method. The structural characterization of the film and powder showed that similar crystallite sizes are obtained in samples heat-treated at the same temperature. Thermo-gravimetric analysis and differential scanning calorimetry were performed in order to determine the activation energies of In2O3 formation from precursors and subsequent crystal growth of both kinds of samples. Absorption measurements showed that the bandgap of the sol-gel polycrystalline films deposited on c-oriented sapphire is in excellent agreement with the one found in bulk and epitaxial indium oxide. The annealed films were found to be highly conductive with carrier concentration generally in excess of 1019 cm− 3. It was observed that the electrical characteristics of films annealed at 700 °C remained stable while those of films annealed at lower temperatures exhibited remarkable changes when measurements were repeated after seven months.