Memristive Electronic Synapses Made by Anodic Oxidation

Memristors have recently gained growing interest due to their potential application as electronic synapses to build artificial neural networks for artificial intelligence systems. However, modulating the conductivity of memristors in a dynamic way to emulate biological synaptic behaviors is very challenging. Here we show the first fabrication of memristive electronic synapses using a dielectric film (TiO_2–x) synthesized via an electrochemical anodization method. Pt/anodic TiO_2–x/Ti memristive synapses show reliable and reproducible memristive behavior and fast switching times below 90 ns. By applying ramped voltage stresses, multilevel conductance states have been achieved (using different current compliances or reset voltages), and by applying pulsed voltage stresses, the potentiation and depression rates could be accurately controlled by tuning the pulse amplitudes. The switching is governed by homogeneous charge rearrangements at the TiO_2–x/Ti interface and TiO_2–x thickness modulation. It is concluded that the anodic oxidation method may be a cheap and effective route to fabricate competitive electronic synapses.