Electrode dependence of resistance switching in polycrystalline NiO films

We investigated resistance switching in top-electrode/NiO/Pt structures where the top electrode was Au, Pt, Ti, or Al. For Pt/NiO/Pt and Au/NiO/Pt structures with ohmic contacts, the effective electric field inside the film was high enough to induce trapping or detrapping at defect states and thus resistance switching. For a Ti/NiO/Pt structure with well-defined Schottky contact at Ti/NiO interface accompanied by an appreciable voltage drop, the effective electric field inside the NiO film was not enough to induce resistance switching. For an Al/NiO/Pt structure with a low Schottky barrier at the Al/NiO interface, resistance switching could be induced at a higher voltage since the voltage drop at the Al/NiO interface was not negligible but small.