Interpreting the Presence of an Additional Oxide Layer in Analysis of Metal Oxides–Metal Interfaces in Atom Probe Tomography

Atom Probe Tomography (APT) analysis of specimens embedded with metal oxide/metal leads to nonintuitive observations of a very thin layer of oxide at the interface due to oxygen migration under the influence of electric field in metal oxides. Detailed analyses of the FeO/Fe and ZrO₂/ZrO interfaces are presented, explaining observation of the interfacial oxide layer with APT. These findings are relevant to the observation made for APT analysis of devices such as resistive switching, solar cells, oxides grown on metal/alloy during oxidation and corrosion wherein metal oxide is in interface with metallic layers. Because the APT technique is based on the application of an electric field on the oxide/metal interface, oxygen ions are driven toward the metal electrode and leads to a reaction with the metal and the formation of the additional interfacial oxide layer. Atomistic simulation performed on the FeO/Fe layer subjected to electric field confirms finding of oxygen migration from the oxide layer toward the oxide/metal interface.