High-Performance Single-Active-Layer Memristor Based on an Ultrananocrystalline Oxygen-Deficient TiO_<i>x</i> Film

The theoretical and practical realization of memristive devices has been hailed as the next step for nonvolatile memories, low-power remote sensing, and adaptive intelligent prototypes for neuromorphic and biological systems. However, the active materials of currently available memristors need to undergo an often destructive high-bias electroforming process in order to activate resistive switching. This limits their device performance in switching speed, endurance/retention, and power consumption upon high-density integration, due to excessive Joule heating. By employing a nanocrystalline oxygen-deficient TiO_<i>x</i> switching matrix to localize the electric field at discrete locations, it is possible to resolve the Joule heating problem by reducing the need for electroforming at high bias. With a Pt/TiO_<i>x</i>/Pt stacking architecture, our device follows an electric field driven, vacancy-modulated interface-type switching that is sensitive to the junction size. By scaling down the junction size, the SET voltage and output current can be reduced, and a SET voltage as low as +0.59 V can be obtained for a 5 × 5 μm² junction size. Along with its potentially fast switching (over 10⁵ cycles with a 100 μs voltage pulse) and high retention (over 10⁵ s) performance, memristors based on these disordered oxygen-deficient TiO_<i>x</i> films promise viable building blocks for next-generation nonvolatile memories and other logic circuit systems