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

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 I_ON/I_OFF 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.