Rectifying behavior and transport mechanisms of currents in Pt/BaTiO3/Nb:SrTiO3 structure

The 15-nm-thickness BaTiO3 (BTO) epitaxial film was prepared on the Nb-doped SrTiO3 (NSTO) single crystal substrate using pulsed laser deposition technique. The morphology and structure of the film was measured by the AFM, TEM and XRD, respectively. The current–voltage curves show abnormal backward diode-like rectifying behavior at room temperature, which was discussed using the Schottky barrier model taking into account the movement of oxygen vacancies. The leakage currents under reverse bias were excellently fitted by the Poole–Frenkel (P–F) emission and Fowler–Nordheim (F–N) tunneling mechanisms, respectively. At forward bias, the current was fitted by the space-charge-limited current mechanism. The C–V curves indicate that there is a positive build-in voltage (about 0.56 V) in the Pt/BTO/NSTO structure, which confirms the backward rectifying behavior.

► Pt/BaTiO3/Nb:SrTiO3 structure shows backward diode-like rectifying behavior.
► The reverse currents were fitted by the P–F emission and F–N tunneling mechanisms.
► At forward bias, the currents were fitted by the SCLC mechanism.
► The Schottky barrier model with the movement of oxygen vacancies was discussed.