Cluster-Type Filaments Induced by Doping in Low-Operation-Current Conductive Bridge Random Access Memory

Conductive bridge random access memory (CBRAM) is one of the most representative emerging nonvolatile memories in virtue of its excellent performance on speed, high-density integration, and power efficiency. Resistive switching behaviors in CBRAM involving the formation/rupture of metallic conductive filaments are dominated by cation migration and redox processes. It is all in the pursuit to decrease the operation current for low-power consumption and to enhance the current compliance-dependent reliability. Here, we propose a novel structure of Pt/TaO_x:Ag/TaO_x/Pt with nonvolatile switching at ∼1 μA and achieve a five-resistance-state multilevel cell operation under different compliance currents. Different from the nanocone-shaped filaments reported in traditional Ag top electrode devices, cluster-type filaments were captured in our memory devices, explaining the low-operation current-resistive switching behaviors. Meanwhile, Cu-doped counterpart devices also display similar operations. Such memory devices are more inclined to achieve low-power consumption and offer feasibility to large-scale memory crossbar integration.