High quality ITO film formation by the simultaneous use of cluster ion beam and laser irradiation

In order to prepare tin-doped indium oxide (ITO) films, we have deposited metallic indium (In) and tin (Sn) on a glass substrate at various substrate temperatures (Ts) in conjunction with irradiation of O2 cluster ions. The temperature dependence of the electrical and optical properties of the ITO films prepared was investigated. The resistivity decreased with increasing substrate temperature, and a resistivity of 1.1×10−4 Ω cm was obtained at Ts=300 °C. This is considered to be due to some improvement of the crystalline state of the films as well as an increase of the carrier density. On the other hand, the transparency was found to be almost constant in the temperature region from room temperature (RT) to 300 °C, and it was higher than 90%. In addition, we have prepared ITO films by the simultaneous use of an O2 cluster ion beam and KrF laser irradiation. High quality ITO films with a lower resistivity of 1.0×10−4 Ω cm and a transparency above 90% was able to be formed at Ts=300 °C. A high carrier density of 2.5×1021 cm−3 was obtained. Laser irradiation during ITO film formation as well as irradiation of O2 cluster ions was effective particularly for annealing and activating doped Sn atoms.