Figure 2. Diagram of a cell area and a forming current to classify the emergence of electrical polarity characteristics in resistive switching behaviors.

(a) Diagram as to variation of polarity characteristics in switching behaviors for CoO_x. (b) Diagram as to variation of polarity characteristics in switching behaviors for TiO_2−x. (c) and (d) Diagrams as to variations of polarity characteristics in switching behaviors for NiO_x(1) and NiO_x(2). The data of two different NiO_x layers were shown when changing the deposition conditions of NiO_x layers. (e) Schematic of observed scaling trends on the emergence of the two electrical polarity characteristics when varying a cell area and a forming current.