Synaptic learning and memory functions in SiO2:Ag/TiO2 based memristor devices

Abstract

In this study, a TiO2 thin layer is deliberately inserted in the Pt–Ag/SiO2:Ag/p++-Si memristor to achieve enhanced resistive switching performance in terms of retention and cyclic endurance characteristics. The memristor device exhibits a bidirectional analog switching behavior corresponding to a wide dynamic range of synaptic weight modulation as potentiation and depression under the consecutive positive or negative DC bias sweeps and pulse trains. Moreover, the learning and memory functions, including paired-pulse facilitation and pulse repetition-induced short-term memory to long-term memory transition, are also demonstrated. The relation of the memory stability to the repeated input pulse stimulus and the device conductance with time have also been revealed by the stretched exponential relaxation model. It is shown that the conductance of our newly fabricated Pt–Ag/SiO2:Ag/TiO2/p++-Si memristor device can be modulated by successive Ag-filament growth and dissolution in the SiO2:Ag/TiO2 bilayer oxide structure, which is essential for potential applications in memory devices and artificial neural systems.