AL2O3 / Zr doped HfO2 ferroelectric tunneling junction and its potential applications as memristors

Ferroelectric tunneling junctions (FTJs), with tunable tunneling electroresistance (TER), are promising for many emerging applications including memristors and neurosynaptic computing. Here we propose a novel design of HZO layer based FTJ by adding an extra 3nm-Al2O3 capping layer. The interfacial Al2O3 layer and semiconducting substrate enable sizable TERs even when the thickness of HZO is above 10nm. Evidently the polarization switching in HZO is elusively dominated by atomic scale ferroelectric domains dispersed in the films. Moreover, we demonstrated FTJ synapses with symmetric potentiation and depression characteristics realized by widely tunable conductance, while the spike-timing-dependent plasticity (STDP) can be harnessed from HZO based FTJs. Our results reveal potential opportunities for HZO ferroelectrics as the hardware basis of future neuromorphic computational architecture.