The role of Al atoms in resistive switching for Al/ZnO/Pt Resistive Random Access Memory (RRAM) device

Generally, the resistive switching (RS) behavior of ZnO-based Random Resistive Access Memory (RRAM) utilizing Al electrode is explained by the valance change mechanism (VCM) based on the movement of oxygen vacancies. However, our current experiments demonstrate that the RS behavior can be significantly affected by the inner-diffused Al atoms from electrode as well as oxygen vacancies. We have fabricated Al/ZnO/Pt device and found that the diffusion of Al and formation of AlOX at the ZnO/Pt interface occurs during RS. The Al atoms are diffused to the ZnO layer and appear to act as dopants in the ZnO, producing additional oxygen vacancies. The behavior of Al atoms contributes to quick conductive filament formation, which causes the SET voltage degradation. In addition, the AlOX layer is formed by the redox reaction between diffused Al atom and oxygen near the ZnO/Pt interface. The formation of AlOX layer leads to the lack of oxygen ion required for conductive filament rupture and generates the high fluctuation of RESET process. In this study, the authors aim to demonstrate the role of Al atoms in the ZnO layer to provide useful insight in the application of RRAM device utilizing Al electrode.