Enhance of electrical properties of resistive switches based on Sr0.1Ba0.9TiO3 and TiO2 thin films by employing a Ni–Cr alloy as contact

We have investigated the electric-field-induced resistance-switching phenomena of ReRAM cells based on Sr0.1Ba0.9TiO3 and TiO2 thin films fabricated by rf-sputtering technique. Thin films were sandwiched between Pt, Ti and nichrome bottom electrode and Cu top electrode. The I–V measurements at room temperature are non-linear and hysteretic. Cells based on Sr0.1Ba0.9TiO3 present a unipolar resistance-switching phenomenon and it is symmetric with respect to the voltage polarity, while cells based on TiO2 have a bipolar resistance-switching with asymmetric behavior. From the I–V measurements we demonstrated that the nichrome enhances the resistance-switching characteristics of the cells. A reduction of the voltage needed to achieve the HRS–LRS and LRS–HRS transitions are found and a very clear transition between these states is accomplished, in comparison with ReRAM cells fabricated with Pt and Ti electrodes, whose voltage values are large and no clear transitions are presented. This improvement in resistance-switching behavior can be explained due to O2 vacancies formed in the interface because higher affinity for oxygen of nickel and chromium.