Figure 3. Area dependence of the critical electric field required for switching.
Intrinsic difference between unipolar switching and bipolar switching on their area dependences. (a) Electric field data required to cause a transition from non-memory to bipolar switching for CoOx, TiO2−x and NiOx. (b) Electric field data required to cause unipolar switching for CoOx and NiOx when varying a cell area. The inset shows the thickness dependence on the electric field data. The comparisons with the model based on a soft dielectric breakdown are shown. (c) Schematic of the emergence of the two polarity characteristics in terms of a diagram between a cell area and an electric field intensity.