Highly controllable and stable quantized conductance and resistive switching mechanism in single-crystal TiO2 resistive memory on silicon.

TiO2 is being widely explored as an active resistive switching (RS) material for resistive random access memory. We report a detailed analysis of the RS characteristics of single-crystal anatase-TiO2 thin films epitaxially grown on silicon by atomic layer deposition. We demonstrate that although the valence change mechanism is responsible for the observed RS, single-crystal anatase-TiO2 thin films show electrical characteristics that are very different from the usual switching behaviors observed for polycrystalline or amorphous TiO2 and instead very similar to those found in electrochemical metallization memory. In addition, we demonstrate highly stable and reproducible quantized conductance that is well controlled by application of a compliance current and that suggests the localized formation of conducting Magnéli-like nanophases. The quantized conductance observed results in multiple well-defined resistance states suitable for implementation of multilevel memory cells.