Influence of antimony doping on electrical properties of barium titanate (BaTiO3) thin films

BaTiO3 thin films having a fine grain size <50 nm were prepared by crystallization of an ion-beam sputtered amorphous phase at 923 K for 1 h in air, The effects of Sb-doping on the electrical properties of the films were investigated in the concentration range 0.04-0.6 at%. The overall resistivity of the films depended markedly on the doping concentration, The doping with Sb contributed to enhance the semiconductive character; the resistivity as well as the activation energy for conduction decreased with increasing concentration of Sb. The minimum room-temperature resistivity was attained in samples doped with 0.38 at% Sb. On further increase in doping, the films showed a positive temperature coefficient of resistivity at elevated temperatures. The results suggest that a similar doping effect, such as found in bulk electronic ceramics, occurs in thin dielectric films, and are discussed in relation to doping mechanisms and Heywang's model.