Tailoring the electrical properties of a TiO2 layer by ion-beam irradiation for memristive applications

Reactively sputtered TiO2 thin films on Pt/Ti/SiO2/Si substrates were irradiated with low energy Ar+ ions of different energies to create surface or bulk modifications in the material. Furthermore, the fluence was varied to optimize the level of the modifications, which are e.g. amorphization, surface smoothing, and preferential sputtering of oxygen. These effects were detected by TEM, AFM and supported by TRIDYN simulations, respectively.
The impact of these changes on the electrical properties of the TiO2 layers was monitored by I-V and C-V measurements in top-bottom geometry with Pt, as well as Ti/Pt top contacts. The results indicate a transition from a Schottky-like behavior of the Pt/TiO2 interface to an ohmic one with increasing fluence, which is very similar to the behavior of a Ti/TiO2 interface. Furthermore, the capacity of the complete MIM stack increases with fluence, which points to a reduced effective thickness of the dielectric TiO2 layer after irradiation.

The project is funded by the Initiative and Networking Fund of the Helmholtz Association (Virtual Institute Memriox, VH-VI-422).