Self-assembly of an NbO₂ interlayer and configurable resistive switching in Pt/Nb/HfO₂/Pt structures

A configurable resistive switching response is reported for Pt/Nb/HfO₂/Pt devices subjected to different set compliance currents. When operated at a low compliance-current (∼100 μA), devices show uniform bipolar resistive switching behavior. As the compliance current is increased (∼500 μA), the switching mode changes to integrated threshold-resistive (1S1M) switching, and at still higher currents (∼1 mA), it changes to symmetric threshold switching (1S) characteristic of threshold switching in NbO 2 - δ. These switching transitions are shown to be consistent with the development of an NbO_2-δ interlayer at the Nb/HfO₂ interface that is limited by the set compliance current due to its effect on oxygen transport and local Joule heating. The proposed mechanism is supported by finite element modeling of the 1S1M response assuming the presence of such an interlayer. These findings help to understand role of interface reactions in controlling device performance and provide a means for the self-assembly of integrated 1S1M resistive random access memory structures.