Resistive switching at the high quality metal/insulator interface in Fe3O4/SiO2/α-FeSi2/Si stacking structure

Abstract

Fe3O4-based films composed of ubiquitous elements are promising for resistive switching. In general, the disadvantage of this film is the low Off/On resistance ratio. We achieved the highest resistance ratio in a Fe3O4-based stacking structure including a thin SiO2 layer with a high quality interface. For fabrication of the stacking structure, Fe oxide films were epitaxially grown on the intentionally formed α-FeSi2 layers on Si substrates, where the high quality epitaxial interfaces were formed owing to the α-FeSi2 layer role: blocking of Si atom diffusion from the substrate through the interface. The high quality Fe3O4/α-FeSi2 interfaces were oxidized by the low O2 pressure annealing process to succeed in inserting thin SiO2 layers at the interfaces. The resulting stacking structure of the Fe3O4 film/SiO2 layer/α-FeSi2 layer showed the resistive switching behavior with the resistance ratio of ∼140 which is the highest value of Fe3O4 materials. This high value comes from much higher resistance in the high resistive state because the stacking structure has a thin SiO2 insulator layer with high quality interfaces without defects working as leakage sites. This means overcoming the disadvantage of conventional Fe3O4-based films, low resistance ratio, and demonstrates the possibility of realization for rare-metal-free resistance random access memory.