Transition from unipolar to bipolar, multilevel switching, abrupt and gradual reset phenomena in a TaN/CeO2/Ti: /Pt memory devices

We report the transition from unipolar to bipolar switching, multilevel resistive switching, abrupt and gradual reset phenomena in a TaN/CeO2/Ti: /Pt memory devices. Multilevel resistive switching can be successfully obtained by varying the current compliance in the set process. It was observed that increasing the value of current compliance during the set process decreases the set voltages of the devices and as well as deceases the low and high resistance states, respectively. In addition, we have also observed coexistence of abrupt and gradual reset transition in a Ta/CeO2/Ti: /Pt memory cell. The device exhibits the excellent bipolar resistive switching characteristics such as endurance performance, device-to-device variability (D2D) and good retention time 10(4) s. The oxidation of the TaN top electrode creates an Ohmic contact with CeO2 film and hence injects positively charged oxygen vacancies into the switching layer which looks to be responsible for resistive switching.