Nano Lett. 2016 Apr 13;16(4):2139-44. doi: 10.1021/acs.nanolett.5b02951. Epub 2016 Mar 18.

Observing Oxygen Vacancy Driven Electroforming in Pt-TiO2-Pt Device via Strong Metal Support Interaction.

Nano letters

Moon Hyung Jang, Rahul Agarwal, Pavan Nukala, Dooho Choi, A T Charlie Johnson, I-Wei Chen, Ritesh Agarwal

PMID: 26982325 DOI: 10.1021/acs.nanolett.5b02951

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.

Keywords: Resistive memory; TiO2; electroforming; filament; in situ TEM; oxygen vacancy; strong metal−support interaction

Publication Types

• Journal Article
• Research Support, U.S. Gov't, Non-P.H.S.