Effect of oxygen vacancy and Mn-doping on electrical properties of Bi4Ti3O12 thin film grown by pulsed laser deposition

An amorphous Bi4Ti3O12 phase was formed when films were grown at <400 °C while Bi2Ti2O7 and Bi2Ti4O11 transient phases were developed when films were grown at 400–500 and 600 °C, respectively. A homogeneous Bi4Ti3O12 crystalline phase was formed in the film grown at 700 °C. The high leakage current density (5 × 10−7 A cm−2 at 0.2 MV cm−1) of the film grown at 300 °C under 100 mTorr oxygen partial pressure (OPP) decreased to 2 × 10−8 A cm−2 for the film grown at 200 mTorr OPP, due to the decreased number of intrinsic oxygen vacancies. However, when OPP exceeded 200 mTorr, the electrical properties were deteriorated due to the formation of oxygen interstitial ions. Mn-doping at a suitable level improved the electrical properties of the films by producing extrinsic oxygen vacancies that reduced the number of intrinsic oxygen vacancies. Schottky emission was suggested as the leakage current mechanism of the Bi4Ti3O12 film.