Visualizing the Local Composition Changes during Resistive Switching in Planar TaOx-ReRAMs

Resistive random-access memory (ReRAM) is an attractive concept for the advancement of computing capabilities. TaOx-ReRAMs are among the best candidate devices for resistive switching applications owing to their two stable phases of TaO2 and Ta2O5. However, the difficulty in localizing the conductive filaments and observing specific local structural and compositional changes in the conventional 3D stacked-junction architecture of ReRAM devices denies a clear understanding of the resistive switching mechanism. Herein, we describe the fabrication of a planar nanogap-based Ta/TaOx/Pt ReRAM junction to investigate the local compositional changes during direct resistive switching. Our results emphasize the role of the tantalum atoms’ mobility during the formation of conductive filaments and after the first reset operation. We demonstrate the migration of tantalum atoms during the resistive switching, evidenced by the formation of pure tantalum pillars. Our nanoscale elemental analysis helps elucidate the mechanism of resistance changes in planar TaOx-ReRAMs via direct visualization of the local compositional changes.