On the role of the metal oxide/reactive electrode interface during the forming procedure of valence change ReRAM devices

Abstract

This work investigates the oxygen exchange at the oxide/electrode interface in ReRAM devices and its influence on the forming behaviour.

Recent Progress in Solution‐Based Metal Oxide Resistive Switching Devices

“…[36,37] The VCM cells structure commonly uses active metals such as Ta, Hf, Ni, Al, and Ti as the ohmic electrode and Pt or Au as the counter electrode material or as another high work function electrode, which is chemically inert (i.e., noble electrode) to guarantee an appropriate Schottky barrier. [35,38] The ECM cell typically uses Ag or Cu as the active electrode due to reversibility of the electrode half-cell reactions and the higher mobility compared to other ions. Thus, the electromigration of metal cations through the resistive switching layer induce a variation on the internal resistance of the device.…”

“…[269] To control the electroforming voltage, or even eliminate it, a low work function electrode or capping layer with a high oxygen-getter like activity is selected, with Ti, Al, Ta, and Hf being preferred for inert-active-asymmetric structures. [38,121,270,271] When the chemical reactive metal, also called oxygen exchange layer (OEL), is in contact with the metal oxide resistive switching layer, ion transfer occurs instantly across the interface due to the difference in the free energy of metal oxide formation of the two systems. The interfacial ion transfer is highly important, specifically the extraction of oxygen ions from the resistive switching layer during the process of electroforming, which is vital for a stable operation of RRAM devices.…”

Laser-Assisted Interface Engineering for Functional Interfacial Layer of Al/ZnO/Al Resistive Random Access Memory (RRAM)

“…As an electrode for ZnO-based RRAMs, inert metals (e.g., Pt) forming a Schottky barrier and reactive metals (e.g., Al) forming an Ohmic contact have been widely employed. − A distinct trade-offs between performance and reliability was identified depending on the interfacial properties of electrode materials. In general, Pt electrodes are known to suppress interfacial redox reactions and to be oxygen permeable. , With the absence of labile interfacial layers, ZnO-based RRAMs utilizing Pt electrodes are believed to lend excellent reliability but with a narrow memory window and large operating voltage.…”

Atomistic Insights on the Full Operation Cycle of a HfO2-Based Resistive Random Access Memory Cell from Molecular Dynamics

“…13−15 The most used AE materials are Ti, Hf, and Ta due to their oxygen scavenging ability and good electrical performance. 14,16 Despite the significant experimental 17 and theoretical 18 evidence supporting the switching mechanism described above, the nature of this phenomena, operating at the nanoscale and in ultrafast regimes, has precluded the development of a detailed, atomic-level understanding of the formation and rupture of the CF, much less an understanding of the variability in the switching and stability of the CF.…”

“…For a bipolar behavior, metals with high oxygen affinity are chosen as the active electrode (AE), whereas inert metals are preferred for the inactive electrode (IE). The AE plays an important role in the operation of VCM cells because it acts as an oxygen exchange layer, creating a substoichiometric region at the oxide interface that contributes significantly to reduce the forming voltage and improve the endurance and retention of the cell. − The most used AE materials are Ti, Hf, and Ta due to their oxygen scavenging ability and good electrical performance. , …”