Grain boundary assisted bipolar resistive switching in solution-processed NiO films

This study investigates the impact of incorporation of Al layer into the Au/NiO interface of spin-coated NiO based resistive random access memory (RRAM) devices with ITO as the bottom electrode. The Al/NiO interface combined with NiO/ITO interface forming dual-oxygen-reservoir device structure increases the defect density. Excellent bipolar resistive switching characteristics are observed with enlarged current ON/OFF ratio up to 10(5) in Au/Al/NiO/ITO device. The RS phenomenon, mediated by the grain boundaries in the polycrystalline NiO thin films, is driven by the defects or oxygen vacancies in the insulating oxide layer which form the localized conductive filaments. Further, the switching properties of Au/NiO/ITO devices without Al layer were also discussed. The associated conduction mechanism was found to differ in devices with and without Al layer.