High-Conductance, Ohmic-like HfZrO4 Ferroelectric Memristor

The persistent and switchable polarization of ferroelectric materials based on HfO2-based ferroelectric compounds, compatible with large-scale integration, are attractive synaptic elements for neuromorphic computing. To achieve a record current density of 0.01 A/cm2 (at a read voltage of 80 mV) as well as ideal memristive behavior (linear current-voltage relation and analog resistive switching), devices based on an ultra-thin (2.7 nm thick), polycrystalline HfZrO4 ferroelectric layer are fabricated by Atomic Layer Deposition. The use of a semiconducting oxide interlayer (WOx<3) at one of the interfaces, induces an asymmetric energy profile upon ferroelectric polarization reversal and thus the long-term potentiation / depression (conductance increase / decrease) of interest. Moreover, it favors the stable retention of both the low and the high resistive states. Thanks to the low operating voltage (<3.5 V), programming requires less than 10^-12 J for 20 ns long pulses. Remarkably, the memristors show no wake-up or fatigue effect.