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 (T-s) in conjunction with irradiation of O-2 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 x 10(-4) Omega cm was obtained at T-s = 300 degreesC. 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 degreesC, and it was higher than 90%. In addition, we have prepared ITO films by the simultaneous use of an O-2 cluster ion beam and KrF laser irradiation. High quality ITO films with a lower resistivity of 1.0 x 10(-4) Omega cm and a transparency above 90% was able to be formed at T-s = 300 degreesC. A high carrier density of 2.5 x 10(21) cm(-3) was obtained. Laser irradiation during ITO film formation as well as irradiation of O-2 cluster ions was effective particularly for annealing and activating doped Sn atoms. (C) 2002 Elsevier Science B.V. All rights reserved.