Gradual set dynamics in HfO2-based memristor driven by sub-threshold voltage pulses

The switching dynamics of filamentary Pt/HfO2/TiN memristive devices is managed through sub-threshold pulses in order to display gradual resistance decrease useful for analog logic computation based on spiking networks. Such memristive devices are known to display abrupt set transitions (resistance decrease) that require current limitation because of the triggering of a threshold switching event. In this report, we demonstrate the gradual resistance decrease driven by trains of identical sub-threshold pulses. The experimental finding is explained by a compact model considering a gradual closure of the filament interruption and a following lateral filament growth.