Resistive switching in thermally oxidized titanium films

Polycrystalline rutile TiO₂ thin films were prepared on Pt/Ti/SiO₂/Si substrates by thermal oxidation of a 100nm thick titanium film at temperatures between 500°C and 800°C. We observed stable nonvolatile unipolar switching in the films oxidized at 600°C to 800°C. Retention measurements showed stable ON and OFF states for a time of at least 24h at room temperature, if there was a sufficient relaxation period between the switching event and the start of the read out process. Without any appropriate time, we observed an increase in resistance in the high resistance state (HRS) after the RESET process. In contrast, the low resistance state (LRS) did not show a time dependent resistance change after the SET process.