Multifunctional double active layers formed with electrochemically controlled nanoparticle dispersion for resistive switching memory arrays

Expanding resistive random-access memory (RRAM) from a single device to an array requires a selector to suppress the sneak path and an external device to control the compliance current. Thus, a unique crossbar array that can be independently driven through the novel design of a multilayer RRAM structure with intelligently controlled Cu2O consisting of nanoparticles embedded in the amorphous matrix (ANPs) is proposed. The ANPs-Cu2O active layers are prepared by electrodeposition, and the negative shift of the deposition potential induces a higher density and smaller size of the nanoparticles. The ANPs-Cu2O films show different set voltages and extremely uniform reset voltages, and thus a functional double active layer (DAL) structure consisting of two ANPs-Cu2O layers with different set voltages is proposed. The electrochemically fabricated VCu-controlled DALs effectively protected the reverse current from the self-rectifying characteristics of a large forward/reverse current ratio, thus realizing selector-less RRAMs. In addition, the soft-breakdown showing filament formation in the upper layer reveals the saturation current step acting as a self-compliance current without the assistance of transistors. Finally, a 4 x 4 crossbar DAL RRAM array with transistor-less self-rectification is demonstrated, which shows excellent memory performance and endurance without interfering with adjacent cells.

Automated summary

In this study, a unique crossbar array structure was proposed, which can be independently driven through the novel design of a multilayer RRAM. The ANPs-Cu2O active layers prepared by electrodeposition showed different set voltages and uniform reset voltages. The VCu-controlled DALs effectively prevented reverse current and achieved selector-less RRAM. The experimental results demonstrated that the array exhibited excellent memory performance and endurance without interfering with adjacent cells.