Effects of UV light irradiation and excess Zn atoms in the film preparation of ZnO:Al film by sputtering were examined. When a glass substrate was irradiated by W light of a 0.5-kW Hg lamp, film resistivity decreased to 70% of the resistivity of the him deposited on the initial non-irradiated substrate. Increases of both carrier concentration and Hall mobility were observed. This was due to the atomic excitation of depositing Zn or O atoms, not to the thermal effect through W irradiation. An additional supply of Zn during the sputtering of ZnO:Al (2 wt%) target decreased the film resistivity, and carrier concentration increased drastically at a substrate temperature of 250 degrees C. This was due to the improvement of film crystallinity by the addition of Zn atoms.