title: Observing Oxygen Vacancy Driven Electroforming in Pt-TiO2-Pt Device via Strong Metal Support Interaction.
abstract: Oxygen vacancy formation, migration, and subsequent agglomeration into conductive filaments in transition metal oxides under applied electric field is widely believed to be responsible for electroforming in resistive memory devices, although direct evidence of such a pathway is lacking. Here, by utilizing strong metal-support interaction (SMSI) between Pt and TiO2, we observe via transmission electron microscopy the electroforming event in lateral Pt/TiO2/Pt devices where the atomic Pt from the electrode itself acts as a tracer for the propagating oxygen vacancy front. SMSI, which originates from the d-orbital overlap between Pt atom and the reduced cation of the insulating oxide in the vicinity of oxygen vacancies, was optimized by fabricating nanoscale devices causing Pt atom migration tracking the moving oxygen vacancy front from the anode to cathode during electroforming. Experiments performed in different oxidizing and reducing conditions, which tune SMSI in the Pt-TiO2 system, further confirmed the role of oxygen vacancies during electroforming. These observations also demonstrate that the noble metal electrode may not be as inert as previously assumed.
authors.affiliation: Department of Materials Science and Engineering, ‡Department of Physics and Astronomy, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States.
authors.forename: Moon Hyung
authors.initials: MH
authors.lastname: Jang
authors.affiliation: Department of Materials Science and Engineering, ‡Department of Physics and Astronomy, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States.
authors.forename: Rahul
authors.initials: R
authors.lastname: Agarwal
authors.affiliation: Department of Materials Science and Engineering, ‡Department of Physics and Astronomy, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States.
authors.forename: Pavan
authors.initials: P
authors.lastname: Nukala
authors.affiliation: Department of Materials Science and Engineering, ‡Department of Physics and Astronomy, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States.
authors.forename: Dooho
authors.initials: D
authors.lastname: Choi
authors.affiliation: Department of Materials Science and Engineering, ‡Department of Physics and Astronomy, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States.
authors.forename: A T Charlie
authors.initials: AT
authors.lastname: Johnson
authors.affiliation: Department of Materials Science and Engineering, ‡Department of Physics and Astronomy, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States.
authors.forename: I-Wei
authors.initials: IW
authors.lastname: Chen
authors.affiliation: Department of Materials Science and Engineering, ‡Department of Physics and Astronomy, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States.
authors.forename: Ritesh
authors.initials: R
authors.lastname: Agarwal
keywords: Resistive memory; TiO2; electroforming; filament; in situ TEM; oxygen vacancy; strong metal−support interaction