Dependence of InGaZnO and SnO2 thin film stacking sequence for the resistive switching characteristics of conductive bridge memory devices

In this study the switching mechanism of CBRAM of single layered and their hybrid oxide device structures have been investigated. The single layered devices and an Ag/SnO2/IGZO/Pt hybrid device show typical bipolar resistive switching while just by interchanging the stacking sequence, a stable and reproducible unipolar resistive switching is observed. The improved resistive memory characteristics are also observed in hybrid devices with improved ION/IOFF ratio, low operating voltages and better endurance and retention characteristics. [Display omitted] •Switching mechanism of CBRAM with hybrid dielectric (SnO2/IGZO) is investigated.•Typical bipolar switching is observed for the Ag/SnO2/IGZO/Pt device.•Stable unipolar switching is observed for the Ag/IGZO/SnO2/Pt device.•The switching difference is elucidated from different diffusion rates of Ag ions. We have investigated the switching mechanism of conductive bridge random access memory (CBRAM) with Ag/SnO2/Pt, Ag/InGaZnO(IGZO)/Pt and their hybrid oxide devices with different stacking sequence (Ag/SnO2/IGZO/Pt and Ag/IGZO/SnO2/Pt). Typical bipolar resistive switching is observed in single layered devices and an Ag/SnO2/IGZO/Pt hybrid device. Interestingly, a stable and reproducible unipolar resistive switching is observed for a hybrid device with a stacking sequence of Ag/IGZO/SnO2/Pt. This result suggests that the staking sequence of dielectrics in the IGZO and SnO2 electrolyte determines unipolar or bipolar switching. The different switching types in the hybrid electrolyte are based on different migration or diffusion rates of Ag ions in the solid electrolyte and redox reaction rates at the electrodes. And as compared to single layered devices, the hybrid structured devices exhibit low operation voltages, higher ION/IOFF ratio, uniform switching cycles and better endurance and retention characteristics. The results and switching mechanisms demonstrated here in hybrid devices can be extended to other hybrid devices based on CBRAM device.