Resistive switching, endurance and retention properties of ZnO/ HfO2 bilayer heterostructure memory device

This work reports the fabrication of resistive memory device with a bilayer ZnO/HfO2 structure. Highly stable and uniform bipolar resistance switching (RS) characteristics were attained when HfO2 interfacial layer is introduced in ZnO device. The bilayer device attains good resistive switching with increased resistance ON-OFF ratio of the order of similar to 10(2), better dc endurance of > 10(2) cycles and retention of >10(4) s at room temperature. X-ray Photoelectron Spectroscopy (XPS) investigation is also done and it is confirmed that oxygen vacancies in ZnO thin film are responsible for improved resistance switching. The current-voltage (I-V) relationship reveals that switching behavior of these devices is mainly dominated by Space-Charge-Limited-Current mechanism (SCLC) regulated due to localized oxygen vacancies. Effect of temperature on the electrical conductivity has also been investigated to analyze the behavior of Low Resistance States (LRS) and High Resistance States (HRS). The findings imply that the bilayer ZnO/HfO2 device structure is a promising one for upcoming non-volatile memory applications.