Resistive Switching Characteristics of HfO_x-Based Memristor by Inserting GeTe Layer

In this study, by inserting a GeTe layer as the current suppression layer and the heating layer, we improved the forming yield (~91%), memory window (> $10^{{3}}$ ), and resistive switching uniformity of HfOx-based memristor. Two forming polarities including positive forming (PF) bias and negative forming (NF) bias were applied to study resistive switching characteristics. After the PF process, the device shows unstable and volatile behavior that is related to ovonic threshold switching (OTS) characteristic. Negative differential resistance (NDR) phenomenon was observed during the NF process. In addition, the device exhibits nonvolatile characteristic, multilevel resistive switching, and good endurance (> $10^{{5}}$ ) after the NF process. We also proposed a corresponding physical model to explain two resistive switching characteristics of the NF and PF processes.