Forming free resistive switching in Au/TiO2/Pt stack structure

Forming free resistive switching property of TiO2 films deposited on Pt/Ti/SiO2/Si substrates was studied in this contribution. The surface morphology of TiO2 films was studied by atomic force microscopy (AFM). The chemic states of Ti and O elements were measured by X-ray photoelectron spectrum (XPS). The resistive switching property of the sample was measured using Au/TiO2/Pt capacitor structure fabricated by evaporating Au top electrode. Smooth surface and dense cross structure were observed by AFM and scanning electron microscopy. Oxygen vacancies in TiO2 film were confirmed by XPS. Forming free resistance switching was confirmed by the current-voltage measurement and the resistance ratio is larger than two orders of magnitude at 2.5 V. The XPS spectrum, asymmetric current loops and conduction mechanism fitting results indicated that the asymmetric electrode structure and oxygen vacancies are the origin of the resistive switching.