Effect of controlled Mn doping on transition of oxygen vacancies in Bi2Ti2O7 thin films: An electrochemical study

Crystalline pyrochlore Bi2Ti2O7 (B2T2) thin films were well formed at 300 °C under 740 mTorr of oxygen partial pressure using pulsed laser deposition. In order to improve the electrical properties of the dielectric B2T2 films, Mn ions were doped into the films and their influence was investigated. Improvement in electrical behavior, especially leakage current density were revealed via impedance spectroscopy and electrochemical studies. Mn doping at an appropriate level improved the electrical properties of the films by affording extrinsic oxygen vacancies that reduced the number of intrinsic oxygen vacancies acting as electron trap sites at the interface between the Pt electrode and the B2T2 film. Schottky emission was posited as the leakage current mechanism in the 10 mol% Mn doped B2T2 (Mn:B2T2) films. The barrier height between the Pt electrode and the Mn:B2T2 film was approximately 1.46 eV, but decreased to 0.51 eV for the non-doped film due to large numbers of intrinsic oxygen vacancies.