Stabilization of resistive switching in Pt/HfO_x/NiO_y/Ni stack by localized NANO-filamentary nucleation of oxygen vacancies

The lack of spatio-geometrical control of conductive filaments in resistive switching oxides leads to operational dispersion and performance instability. We have experimentally demonstrated a method to localize the nucleation of conductive channels in Pt/HfO_x/NiO_y/Ni configuration via a sequential in situ cum ex situ electroforming process comprised of field-induced formation and local dissolution of intricately structured conductive percolation channels partially composed of oxygen-deficit and partially of metal-rich filamentary paths present respectively in the hafnia and NiO_y layers. The stable low power operation with fairly acceptable OFF/ON resistance ratio with only 8% loss in resistance window and feeble variation in operational parameters makes the demonstrated method a potential route for improving the performance of the future non-volatile memory devices. The improved operational stability has been found to be originated from the localization of the filamentary nucleation of oxygen vacancies in HfO_x layer just above the pre-formed single metallic filament in NiO_y layer.