Synaptic functions and a memristive mechanism on Pt/AlOx/HfOx/TiN bilayer-structure memristors

摘要

In this paper, Pt/AlOx/HfOx/TiN bilayer-structure memristors were fabricated by atomic layer deposition. Some essential synaptic biological functions are achieved in such a single inorganic electronic synapse using analog resistive switching behavior. With the aid of x-ray photoelectron spectroscopy (XPS), the non-uniform distribution of oxygen vacancies in the Pt/AlOx/HfOx/TiN memristor has been confirmed. The oxygen-deficient HfOx layer has much more oxygen vacancies than the AlOx layer. In the Pt/AlOx/HfOx/TiN device, the formation/rupture of the nanoscale conductive filaments of oxygen vacancies probably occurs in the AlOx layer. The thickness of the filaments can be altered with the amplitude and width of the stimulating pulses. With the conductive filaments becoming narrower to a quantum wire, quantum conductance has been observed during the bipolar reset process of Pt/AlOx/HfOx/TiN. A memristive switching mechanism of a bilayer metal oxide synaptic device has been proposed to explain synaptic plasticity based on the oxygen vacancies migration/diffusion model.