Enhancing the switching speed of oxide-based memristive devices at a low voltage level is crucial for their use as non-volatile memory and their integration into emerging computing paradigms such as neuromorphic computing. Memristive devices based on the valence change mechanism (VCM) have exhibited substantial potential not only in the domain of digital emerging memories but also in analog neuromorphic and in-memory computing applications. Specifically, filamentary ReRAM devices have been reported to exhibit significant temperature accelerated switching kinetics. Here we demonstrate a significant improvement in the speed of the SET process by engineering this thermal acceleration for the memristive model system SrTiO₃.

We have implemented a novel approach of thermal engineering in the ReRAM device stacks, without altering the properties of the switching oxide or its interfaces. In this work we present two different variations: i) we have used reduced tantalum oxide as the main body of the active electrode, which is electrically conductive, but still has relatively low thermal conductivity (TaO_x, κ ~ 5.9 W/m K), and ii) we have introduced an electrically insulating, low thermal conductivity interlayer (HfO₂, κ ~ 0.6 W/m K), embedded inside the Pt (κ ~ 44.5 W/m K) top electrode of the device. In both approaches, the introduced materials act as a thermal barrier in the z-direction, which reduces the thermal conductance through the active top electrode.

By incorporating a heat blocking layer (HfO₂ or TaO_x) positioned within the active electrode of our STO model system VCM devices, we have been able to achieve a remarkable acceleration in switching speed, reaching up to 10³ times faster in terms of time. In addition, this approach enables an approximate 30% reduction in the switching voltage required to sustain the switching speed. This not only improves the energy efficiency of ReRAM cells, but also positions them well for integration with low-voltage transistor technology. The choice of HfO₂ or TaO_x as heat barrier materials facilitates the implementation of our approach due to the wide availability of the materials and the simplicity of their fabrication process. The fact that there are no modifications of the main stack of the ReRAM device (ohmic contact/switching oxide/Schottky contact) makes this approach a more general mechanism to accelerate the switching kinetics in ReRAM devices and, not limited to the specific memristive SrTiO₃ stack used in this work.

In conclusion, we were able to accelerate up to x10³ time the SET speed process of filamentary ReRAM devices or reduce the operation voltage by up to ≈ 30% to maintain the switching speed, by thermally engineering the heat dissipation along the active metal electrode of the devices. This opens a window towards more efficient device operation with a strategy that is CMOS compatible, making our approach easily implemented in established processes of ReRAM device fabrication.