Orthorhombic phase induced ultra-low operation voltage in La-doped BiFeO3 resistive switching devices

Abstract

In this study, the effect of La doping on the resistive switching properties of BiFeO3 (BFO) is systematically discussed. It was found that La doping can not only inhibit the volatilization of Bi and thus diminish the intrinsic oxygen vacancy of BFO, but also improve the lattice symmetry of BFO for generating orthorhombic phase BFO. To confirm these microstructural changes and their relation to the resistive switching properties of BFO, the phase structures, chemical compositions, microstructures, energy band structures, and interfacial features of BFO with different La-doping concentrations are characterized. The resistances of BFO devices with different La doping concentrations also show significant differences, especially, the 15 at. % La-doping BFO device exhibits ultra-low operation voltage of only −0.15 V and good cycling consistency due to the integration of low oxygen vacancy concentrations and precipitation of the orthorhombic phase. The multiple effects of La doping on the resistive characteristics of BFO discussed in this paper provide a reference for the application of BFO in the field of resistive memories.