Effect of the stoichiometry of niobium oxide on the resistive switching of Nb2O5 based metal-insulator-metal stacks

The oxygen concentration profiles, which develop at the interfaces between niobium pentoxide and the Al or Pt electrode in a metal-insulator-metal stack, were investigated by means of the X-ray and electron energy loss spectroscopies in a scanning transmission electron microscope with high resolution. The contact between Al and Nb2O5 was found to facilitate diffusion of oxygen from Nb2O5 to the Al electrode and to support the formation of a thin aluminum oxide layer at the Nb2O5/Al interface. In contrast, almost no diffusion of oxygen from Nb2O5 was observed at the Nb2O5/Pt interface. Different extent of the oxygen diffusion correlates with the observed differences in the resistive switching of the Pt/Nb2O5/Al and Pt/Nb2O5/Pt stacks.