Enhancing the synaptic properties of low-power and forming-free HfOx/TaOy/HfOx resistive switching devices

The incorporation of a TaOy layer in a HfOx/TaOy/HfOx resistive switching memory stack results in low-power (similar to nW in pulsing mode) and forming-free operation. With this material configuration, we derive a stable memory window (similar to 10(2)), good cycling variability (sigma/mu < 0.6) and robust pulse endurance (10(6)). The switching phenomenon is confined in the TaOy layer because of its higher oxygen content and deeper oxygen vacancy levels in contrast to the surrounding HfOx layers that act as series resistances. This enables the manifestation of analog switching characteristics, sub-pJ energy consumption for both SET and RESET transitions, enhanced synaptic weight modulation, Spike-Timing-Dependent-Plasticity and short-term plasticity effects of our devices that play an important role in emulating the function of a biological synapse.