Low‐resistivity tin‐doped indium oxide thin films have been implanted with115In+ions in order to increase the concentration of electrically active oxygen vacancies. The carrier density, Hall mobility, and optical properties of the as‐implanted films have been determined as a function of In+dose. Three dose ranges are described. For doses up to 2.5×1014/cm, both carrier density and Hall mobility initially decrease to respective saturation values. Then, at doses between 2.5×1014/cm2and 2.5×1015/cm2, the carrier density increases while the mobility remains constant. At still higher doses, the Hall mobility begins to decrease abruptly. Mechanisms accounting for the implantation‐induced changes in each of these three dose ranges are discussed. In particular, it is shown that the rate of increase of the carrier density with In+dose in the intermediate range agrees quantitatively with the rate of production of oxygen‐vacancy donors that is necessary to fully accommodate the implanted In substitutionally on In2O3lattice sites during implantation. ©1995 American Institute of Physics.