Conduction mechanism of La-, Nb-doped BaTiO3 thin films by doping MOCVD

Epitaxially grown semiconductive La-doped and Nb-doped BaTiO3 thin films were prepared by doping MOCVD. The doping MOCVD is the method of the supplying simultaneously additive dopant precursor, i.e. La or Nb, with dominant precursor, i.e. Ba, Ti and Oxygen. The minimum resistivity of La-doped BaTiO3 films and Nb-doped BaTiO3 films as deposition at room temperature were 1.5x10(-1) Omega .cm and 2.8 x 10(-2)Omega .cm, respectively. These values were similar to that of single crystal semiconductive BaTiO3. Resistivities of La-doped BaTiO3 films at room temperature were not varied with increasing of annealing temperature under air up to deposition temperature. On the other hand, resistivities of Nb-doped BaTiO3 films were increased by same annealing treatment. From these results, it was considered that the conduction mechanism of La-doped BaTiO3 thin film was the hopping conduction same as that reported on bulk ceramics, and that the conduction mechanism of Nb-doped BaTiO3 thin films was related to oxygen vacancy.