Effects of ambient high-temperature annealing on microstructure, elemental composition, optical and electrical properties of indium tin oxide films

500 nm-thickness indium tin oxide (ITO) films were deposited onto quartz glass substrates and annealed at 700–1000 °C for 1 h. Microstructure, elemental composition, optical and electrical properties of ITO films were systematically studied. It is found that the crystalline is cubic bixbyite, and preferred orientation changes from mainly (2 2 2) to (4 0 0) with the increasing temperature. Obvious changes are also observed in morphology of ITO films during the ambient high-temperature annealing. ITO film annealed up to 1000 °C is still stable Sn doped In2O3, oxygen defects decreases and adsorbed oxygen increases. The resistivity of ITO films after annealed at 700 and 800 °C firstly increases slightly and then increases sharply, when annealing temperature is increased to 900 and 1000 °C. Average transmittance of these films was 70%–80% and their optical band gap shifts to lower energy with the increase of the annealing temperature.