Understanding the underlying physics of superior endurance in Bi-layered TaOX-RRAM

A comprehensive physical model is introduced to account for the superior endurance characteristics of TaO_X-based RRAM with bi-layered Ta₂O_5-X/TaO_2-X stack by considering the influence of oxygen content in TaO_2-X layer. In the physical model, the TaO_2-X layer acts as an oxygen reservoir to store and release oxygen ions (O^2-) during switching cycles and different oxygen contents in TaO_2-X layer correspond to different capabilities to take redox reactions with O^2-. The proposed model is implemented into an atomic Monte-Carlo simulator involving the evolution of oxygen distribution in Ta₂O_5-X/TaO_2-X stack to reproduce the impacts of different TaO_2-X layers on endurance performance. Results reveal that the optimized TaO_2-X layer with the feature of easily storing O^2- as lattice oxygen (LO) during SET and decomposing to release O^2- during RESET is beneficial to enhance the endurance property.