Effect of annealing treatment on the uniformity of CeO2/TiO2 bilayer resistive switching memory devices

Bilayer CeO₂/TiO₂ films with high-k dielectric property were prepared by rf magnetron sputtering technique at room temperature. Effect of annealing treatment on resistive switching (RS) properties of bilayer CeO₂/TiO₂ films in O₂ ambient at different temperature in the range of 350–550 °C was investigated. Our results revealed that the bilayer films had good interfacial property at 500 °C and this annealing temperature is optimum for different RS characteristics. Results showed that bilayer CeO₂/TiO₂ film perform better uniformity and reliability in resistive switching at intermediate temperature (i.e. 450 °C and 500 °C) instead of low and high annealing temperature (i.e. 350 °C and 550 °C) at which it exhibits poor crystalline structure with more amorphous background. Less Gibbs free energy of TiO₂ as compared to CeO₂ results in an easier re-oxidation of the filament through the oxygen exchange with TaN electrode. However, the excellent endurance property (>2500 cycles), data retentions (10⁵ s) and good cycle-to-cycle uniformity is observed only in 500 °C annealed devices. The plots of cumulative probability, essential memory parameter, show a good distribution of Set/Reset voltage.