Tuning the active interface in TiO2 thin film-based memristors prepared by PVD

In this work, the resistive switching and the conducting mechanism of forming-free TiO2 thin films between Ti and Pt electrodes were investigated. The devices were fabricated employing Physical Vapor Deposition (PVD) methods. Ti/TiO2 films were prepared with a cathodic arc system while Pt contacts were deposited by sputtering. Different TiO2 structures (amorphous, anatase, rutile) and thicknesses (60-240 nm) were analyzed through current-voltage (IV) characteristic curves and resistance hysteresis switching loops (RHSL). Amorphous TiO2 produced more conductive devices, with a circulation path, both in IV and RHSL, opposite to that of crystalline TiO2. From these results, the TiO2-Ti was found to be the active interface in devices based on the amorphous phase, while the Pt-TiO2 interface was the active one for anatase and rutile. The results showed that the selection of the TiO2 growth conditions allows to tune which will be the active interface that produces the resistive changes by choosing the structure of the films, as well as the degree of non-linearity of the electrical conduction of the device by varying the thickness of the TiO2 (anatase) film.