Effect of the Threshold Kinetics on the Filament Relaxation Behavior of Ag-Based Diffusive Memristors

Owing to their unique features such as thresholding and self-relaxation behavior diffusive memristors built from volatile electrochemical metallization (v-ECM) devices are drawing attention in emerging memories and neuromorphic computing areas such as temporal coding. Unlike the switching kinetics of non-volatile ECM cells, the thresholding and relaxation dynamics of diffusive memristors are still under investigation. Comprehension of the kinetics and identification of the underlying physical processes during switching and relaxation are of utmost importance to optimize and modulate the performance of threshold devices. In this study, the switching dynamics of Ag/HfO2/Pt v-ECM devices are investigated. Depending on the amplitude and duration of applied voltage pulses, the threshold kinetics and the filament relaxation are analyzed in a comprehensive approach. This enables the identification of different mechanisms as the rate-limiting steps for filament formation and, consequently, to simulate the threshold kinetics using a physical model modified from non-volatile ECM. New insights gained from the combined threshold and relaxation kinetics study outline the significance of the filament formation and growth process on its relaxation time. This knowledge can be directly transferred into the optimization of the operation conditions of diffusive memristors in neuromorphic circuits.