Role of oxygen vacancies formed between top electrodes and epitaxial NiO films in bipolar resistance switching

We investigated bipolar resistance switching (RS) behavior of a top electrode/epitaxial NiO using Al and Pt as the top electrodes (TEs) and epitaxial NiO deposited at 500 °C (NiO-500) and 700 °C (NiO-700). We found that the contact between Al and Pt TEs and NiO-500 was a high resistance insulating contact, while the contact between the two TEs and NiO-700 was a low-resistance metallic contact. We also found that only NiO-500 with the Pt TE exhibited bipolar RS after an electroforming process. This study suggests that during the formation of the Pt/NiO-500 interface, the amount and behavior of oxygen at the interface seem to play the most important role in bipolar RS behavior. In order to improve the device performance, better control of oxygen content and its movement at the interface seems necessary.

► Interfaces between epitaxial NiO films and top electrodes were studied.
► Resistance switching behavior is strongly controlled by growth temperature of NiO.
► Amount and behavior of oxygen at the interface play the most important role.
► Oxygen vacancies are measured by change in the unit-cell volume of NiO.