Vacuum and Air Annealing Effects on Properties of Indium Tin Oxide Films Prepared by Ion-Assisted Electron Beam Evaporation

Indium tin oxide (ITO) films were deposited on glass substrates by ion-assisted electron beam evaporation, followed by annealing in vacuum and air at different temperatures from 200 to 350 °C with an interval of 50 °C for 1 h. The deposited films were analyzed by a four-point probe method, Hall effect measurement, an X-ray diffraction technique, spectrophotometry, and atomic force microscopy. Results show that the electrical resistivity of ITO films depends on annealing temperature. Its lowest value of 1.07 × 10 -4 Ω cm is obtained at an annealing temperature of 350 °C in vacuum. The optical transmittance of ITO films with a thickness of 500 nm for annealing in air is higher than that in vacuum. The optical band gap and grain size increase with increasing annealing temperature.