Tuning of ionic mobility to improve the resistive switching behavior of Zn-doped CeO₂

Correlation between the resistive switching characteristics of Au/Zn-doped CeO₂/Au devices and ionic mobility of CeO₂ altered by the dopant concentration were explored. It was found that the ionic mobility of CeO₂ has a profound effect on the operating voltages of the devices. The magnitude of operating voltage was observed to decrease when the doping concentration of Zn was increased up to 14%. After further increasing the doping level to 24%, the device hardly exhibits any resistive switching. At a low doping concentration, only isolated V_o existed in the CeO₂ lattice. At an intermediate doping concentration, the association between dopant and V_o formed (Zn, V_o)^× defect clusters. Low number density of these defect clusters initially favored the formation of V_o filament and led to a reduction in operating voltage. As the size and number density of (Zn, V_o)^× defect clusters increased at a higher doping concentration, the ionic conductivity was limited with the trapping of isolated V_o by these defect clusters, which resulted in the diminishing of resistive switching. This research work provides a strategy for tuning the mobility of V_o to modulate resistive switching characteristics for non-volatile memory applications.