Three-state resistive switching in HfO2-based RRAM

We investigate the reset transition of HfO2-based RRAM structures with emphasis on revealing three-state resistive switching effects. We study nonpolar switching in Pt/HfO2/Pt and unipolar/bipolar switching in Pt/Ti/HfO2/Pt structures, respectively. However, three-state resistive switching is only confirmed in the former case by means of various reset methodologies. Using two-step reset experiments it is shown that the transition to the complete reset state occurs at higher voltages if the CF first drops to the intermediate state.