Off-stoichiometry effects on BiFeO3 thin films

The effects of Bi and Fe-excess on the structure, ferroelectric, leakage current and magnetic properties of BiFeO3 (BFO) thin films are reported. BFO with 5% excess exhibits no change in the structure with an improvement in leakage current properties in comparison to stoichiometric BFO. Raman spectroscopy of 10% Bi excess suggests a structural change from monoclinic to rhombohedral accompanied with an improvement of resistivity and ferroelectric polarization switching. A higher Fe-excess leads to the formation of pyrochlore Bi2Fe4O9 and gamma-Fe2O3 that cause an increase in conductivity at the macroscopic scale. The results are discussed in terms of Fe and Bi-excess effects on the defect structure of BFO.

Research Highlights
► We show that Bi excess is decisively influenced the structure of BiFeO3.
► The excess at 10%Bi induce improvement of the ferroelectric properties of BFO.
► Interestingly up to 5%Fe does not deteriorate the DC resistivity of the thin films.
► The excess at 5% does not affect de magnetic properties of BFO.