Competitive conductive mechanism of interstitial Ag and oxygen vacancies in Ag/Ta₂O₅/Pt stack

The transport properties of Ag/Ta₂O₅/Pt with coexisting interstitial Ag and oxygen vacancies are examined by density-functional theory and nonequilibrium Green's function calculation. The results show that the coexistence of interstitial Ag and oxygen vacancies results in a reduced transmission coefficient, implying an antagonistic interaction between Ag and oxygen vacancies. Interstitial Ag atoms may take the position of oxygen vacancies and block the oxygen vacancy channel. Alternatively, oxygen vacancies attract electrons from nearby Ag channels thereby reducing the conductance. By comparing the different dual-component channels, it is found that Ag and oxygen vacancies tend to form a complete oxygen vacancy channel with a few Ag atoms giving rise to higher conductance. Our calculation reveals a competitive conductive mechanism of interstitial Ag and oxygen vacancies and a promising strategy to investigate multicomponent channels and improve the design of future synaptic devices.