Dependence of the SET switching variability on the initial state in HfO sub(x)-based ReRAM

For any application of redox-based resistive switching devices understanding of variability is of major interest. In this work, we analyze the dependence of the SET switching time in pulse measurements of TiN/HfO sub(x)/Pt devices on the initial state before switching. The distribution of the measured SET times covers up to seven decades in one cell. A stochastic as well as a deterministic variability component are identified by relating the initial HRS resistance - obtained from a READ pulse and from the SET pulse for comparison - to the SET time. The different resulting correlations to the SET time for the two descriptions of the initial resistance are analyzed and linked to the polarity and voltage dependence of the HRS. In addition, the origin of the resistance variation is discussed.