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

Abstract

Resistive random-access memory (ReRAM) is an attractive concept for the advancement of computing capabilities. TaO x -ReRAMs are among the best candidate devices for resistive switching applications owing to their two stable phases of TaO 2 and Ta 2 O 5 . 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/TaO x /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 TaO x -ReRAMs via direct visualization of the local compositional changes.

Effective Conduction Path of a C60 Chain in a Nanogap Electrode

“…A fundamental understanding of the effective electrical current path in electronic devices is useful for designing device structures and developing advanced functions. − For conductive channel materials with a sufficiently large size, current paths can be visualized using discharge phenomena caused by high-frequency magnetic fields . When an electrical bias is applied, current is induced in the material, and its path is deformed.…”

“…When an electrical bias is applied, current is induced in the material, and its path is deformed. The deformed material along the current path can be observed by scanning electron microscopy (SEM) or transmission electron microscopy (TEM) imaging. ,− In addition, the deformed material trace can be spatially mapped using Raman spectroscopy . For conductive media at the single-molecule scale, TEM images provide a direct visualization of the conductive channel, such as metallic atoms bridging the gap between two metallic contacts or a fullerene dimer within the gap .…”