300 nm thick tin oxide thin films were deposited on glass by filtered vacuum arc deposition and annealed in air at 300 and 350 degreesC for up to 60 min. The resistivity of the coating before annealing was 3 mohm cm. During the annealing, an electric field E in the range of 0-200 V/cm was applied to the sample parallel to the film surface. As the sample was connected in series to a 5 kOmega resistor, the electric field on the sample was not constant during the annealing, depending on the variation of its resistance. The initial magnitude of the electric field on the sample was in the range of 0-17.4 V/cm. Film resistance decreased as function of short annealing times, reaching a minimum value after I to 3 min, and depended on the applied voltage U. At longer annealing times, the resistance continuously increased up to saturation after 8 min. The magnitude of the saturated resistance also depended on U, that is, on the field in the sample. The lowest electric resistivity (0.6 mohm cm) was obtained at 300 degreesC and U = 100 V (initial field in sample of similar to9 V/cm). The minimum resistivity of annealed films without electric-field application was three times higher, 1.8 mohm cm. However, the minimal resistivity measured when U = 200 V/cm (initial field 19.4 V/cm) was 2.1 mohm cm, i.e., larger by a factor of similar to1.2 than that obtained with no field. The visible transmittance, T, was measured before and after annealing, being 67% before annealing. The transmittance of annealed films depended on the annealing time and the applied field. The highest visible transmittance of films annealed with E = 100 V/cm was 89%, and obtained after annealing for 5 min. The maximal visibility of films annealed with no field was 81%, and obtained after annealing for 8 min. The atomic ratio O/Sn on the film surface decreased linearly with time from similar to2 to similar to0.7 with U = 100 V, but it remained greater than 1.3 at U = 0 V. The O/Sn ratio remained approximately constant ( 2) at a depth larger than 20 nm. (C) 2003 American Vacuum Society.