Ab initio molecular-dynamics simulations of electronic structures and characteristics of Cu/SiO2/Pt memristive stack

Abstract

Memristor, as the fourth passive fundamental circuitry element, has recently received considerable attention due to its appealing prospect for in-memory computing and neuromorphic computing applications. Numerous memristive materials, such as metal oxides, chalcogenides, amorphous silicon, carbon, and polymer nanoparticle materials, have been under intensive research. Within the memristive families, metal oxides attain more attention due to their great scaling, fast switching speed, low power consumption, and long endurance. However, the memristive mechanism and electronic characteristics of the metal oxides still remain controversial. To address this issue, we here investigated the electronic structure and electronic characteristics of a typical memristive stack (i.e., Cu/SiO2/Pt) based on newly developed density functional theory and ab initio molecular-dynamics simulations. Calculated results reveal that the energy barriers required to be overcome for Cu ions to diffuse through Cu electrode, SiO2 active layer, and Pt electrode, are 0.6 eV, 1 eV, and 1.63 eV, respectively. This results in an overall barrier of ～ 1.63 eV for entire Cu/SiO2/Pt stack. Both ion and electron conductivities of the Cu/SiO2/Pt stack are found temperature dependent, while the electron conductivities arising from calculated density of states and band structures, is much higher than the ion conductivity. This obviously facilitates the diffusion of Cu ions and thus can explain the memristive behaviour of the studied device.