Characteristics of the RRAM device and the transistor. (a) The schematic of 1T1R structure. (b) Typical I-V curves of the Cu/HfO2/Pt device in set and reset cycles. The reset points have been notated by Vreset and Ireset. (c) The transfer curve of the N+ transistor. The intrinsic parameters of the transistor (including WunCox/2 L and VT) are abstracted from the slope and the intercept of the fitting line, so the soure-drain resistance is obtained from calculation.