Controlling filament growth mode in resistive random-access memory based on thermal flow

To use resistive random-access memory (ReRAM) in various attractive applications, the guidelines of the device structure are required for controlling memory characteristics. In this study, 3D simulation of oxygen vacancy (V-O) diffusion was performed by adopting a combination of Soret and Fick diffusions as driving forces of V(O)s in NiO layers of Me/NiO/Me devices (Me = Pt, Ru, W). It was demonstrated that the reciprocating motion of V(O)s, accompanying resistive switching, could be reproduced consistently with good cycling endurance for unipolar-type ReRAM. Furthermore, our simulation revealed that the thermal flow from the NiO layer to the electrode (EL) caused V-O migration in the vertical direction, and affected both SET and RESET switching in contrast to previous reports. Accordingly, it is clear that the three-dimensional thermal design of the device structure considering ELs is crucial for tuning memory characteristics by controlling the balance of Fick and Soret diffusions.