Microstructure dependence of leakage and resistive switching behaviours in Ce-doped BiFeO₃ thin films

Abstract

The leakage current and resistive switching (RS) of Ce-doped BiFeO 3 (BCFO) films prepared by the sol–gel method at various annealing temperatures are investigated. With increasing annealing temperature, BCFO changes from an amorphous structure to a crystalline structure, while the leakage current increases due to an increase in the carrier mobility as well as an increase in the oxygen vacancy concentration. Bipolar RS behaviours are observed in BCFO films, which can be attributed to the formation/rupture of metal filaments due to the diffusion of the top electrodes under a bias voltage. With increasing annealing temperature, the forming voltage decreases, while no obvious changes are observed in resistances in both ON and OFF states and programming voltages, demonstrating that the RS occurs in a confined region. The pristine BCFO shows Schottky emission conduction behaviour, while Ohmic conduction and space charge limited conduction dominate in ON and OFF states, respectively.