High-Speed Switching and Giant Electroresistance in an Epitaxial Hf 0.5 Zr 0.5 O 2 -Based Ferroelectric Tunnel Junction Memristor.

HfO 2 -based ferroelectric materials are good candidates for constructing next-generation nonvolatile memories and high-performance electronic synapses and have attracted extensive attention from both academia and industry. Here, a Hf 0.5 Zr 0.5 O 2 -based ferroelectric tunnel junction (FTJ) memristor is successfully fabricated by epitaxially growing a Hf 0.5 Zr 0.5 O 2 film on a 0.7 wt % Nb-doped SrTiO 3 (001) substrate with a buffer layer of La 2/3 Sr 1/3 MnO 3 (∼1 u.c.). The FTJ shows a high switching speed of 20 ns, a giant electroresistance ratio of ∼834, and multiple states (eight states or three bits) with good retention >10 4 s. As a solid synaptic device, tunable synapse functions have also been obtained, including long-term potentiation, long-term depression, and spike-timing-dependent plasticity. These results highlight the promising applications of Hf 0.5 Zr 0.5 O 2 -based FTJ in ultrafast-speed and high-density nonvolatile memories and artificial synapses.