Contact Engineering Approach to Improve the Linearity of Multilevel Memristive Devices.

Physical mechanisms underlying the multilevel resistive tuning over seven orders of magnitude in structures based on TiO/AlO bilayers, sandwiched between platinum electrodes, are responsible for the nonlinear dependence of the conductivity of intermediate resistance states on the writing voltage. To improve the linearity of the electric-field resistance tuning, we apply a contact engineering approach. For this purpose, platinum top electrodes were replaced with aluminum and copper ones to induce the oxygen-related electrochemical reactions at the interface with the AlO switching layer of the structures.