(TiO2)x−(Ta2O5)1−xthin films were prepared with radio-frequency magnetron sputtering deposition in this study. The dielectric constant measured from these films appears to critically depend on the amount ofTiO2incorporated into the film and post-anneal condition. The composition dependence was found similar to that reported on(TiO2)x−(Ta2O5)1−xbulk. The highest value of dielectric constant is about 55 for aTiO2content of 8&percent; and annealing at 800 °C. Compared to pureTa2O5thin films, significant enhancement in dielectric constant is obtained by adding small quantity ofTiO2.©1998 American Institute of Physics.