Resistive switching and synaptic behaviors of an HfO2/Al2O3 stack on ITO for neuromorphic systems

This work reports on the bipolar resistive switching (RS) characteristics and possible applicability to transparent synaptic devices when an ultrathin Al2O3 interfacial layer is introduced between HfO2 and an indium tin oxide (ITO) bottom electrode for an RS device (TaN/HfO2/Al2O3/ITO). The introduction of the Al2O3 interfacial layer on ITO allows for a more gradual current change during the RESET process. As a result, the bilayer RS device offers multilevel resistance states with reasonable controllability under the application of various DC and pulse voltages. Considering the systematic changes in the resistance in accordance with the negative/positive voltage pulses during the potentiation/depression processes, as well as the reasonable spike-timing-dependent plasticity characteristics, the proposed RS bilayer on ITO is a potential candidate for transparent synaptic devices in neuromorphic systems. (C) 2020 Elsevier B.V. All rights reserved.