Figure 1

Resistive switching characteristics of AZO/NiO/Pt capacitor structures under negative applied voltage.

(a–c) Current-voltage (I–V) curves of AZO/NiO/Pt structures, in which the NiO buffer layer has a thickness of 12 nm (a), 20 nm (b) and 30 nm (c). Black and red squares reveal the forming characteristics and resistive switching behavior after forming, respectively. Red, green and blue arrows indicate the positions of the 1^st-, 2^nd- and 3^rd-step forming, respectively. The inset of (a) shows a schematic illustration of AZO/NiO/Pt structures with contacts for electrical measurements. (d) Resistance values of AZO/NiO/Pt structures at initial, high resistance and low resistance states, measured at −0.6 V, as functions of the NiO buffer layer thickness. The inset shows the amplitudes of the 1^st-, 2^nd- and 3^rd-step forming voltages of AZO/NiO/Pt structures with different NiO buffer layer thicknesses.