Resistive switching behavior of sol–gel deposited TiO2 thin films under different heating ambience

We prepared anatase TiO2 films by sol–gel method under three thermal firing conditions to investigate the bipolar resistive switching (BRS) and unipolar resistive switching (URS) in Ag/TiO2/Pt structure. The devices are URS in an air atmosphere at 760 Torr, while those in an oxygen ambience at 1 Torr show BRS accompanying with forming-free and self-compliance. By examining the X-ray photoelectron spectroscopy (XPS) spectrum, different non-lattice oxygen content is observed. High concentration of oxygen vacancy is expected under oxygen-deficient treatment, and that would determine the electrode/oxide interface property and induce switching mode of polarity dependent or not. An improved performance of operation voltage dispersion down to 0.5 V and endurance up to 3000 cycles is obtained for those in reducing Ar.

► Different amounts of non-lattice oxygen were observed in XPS analysis.
► The 3000 endurance cycles and 0.5 V operation voltage dispersion were obtained.
► The TiO2-based RRAMs have great potential for multilevel operation storage.