Controlled charge transport in ZrO2 and its bilayer structures for low-power memory

Redox-based oxide resistive random-access memories (ReRAM) are being pursued as adjustable electronic devices for integrated network applications such as neuromorphic computing. Ion migration, which can be divided into cation (electrochemical metallization memory: ECM) and anion (valence change memory: VCM), defines the electrical response of ReRAM. In this study, the coexistence and control of these two ion migrations are explored in a single memory cell composed of zirconia (ZrO2). The oxygen vacancies, which are responsible for VCM in ZrO2, serve as an active layer, while Ag, as an electrochemically active electrode, is responsible for ECM behavior. The two distinct switching modes were steered by changing the electrode (Ag, Au, Gr), zirconia deposition technique or a bilayer stack of zirconia with the GeSe amorphous monochalcogenide layer. The electrical characteristics of the bilayer stack were superior to other approaches as zirconia and GeSe have different ion transport rates. This induces the confined formation of conductive filaments and only facilitates one ionic movement in both layers, resulting in improved endurance and memory window. Overall, this work encompasses the conducting mechanisms in dielectrics and presents advances in the multi-functionalities of ReRAM for brain-enhanced memory computations.