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

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• 作者：Moon Hyung Jang ; Rahul Agarwal ; Pavan Nukala ; Dooho Choi ; A. T. Charlie Johnson ; I-Wei Chen ; Ritesh Agarwal
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：April 13, 2016
• 年：2016
• 卷：16
• 期：4
• 页码：2139-2144
• 全文大小：383K
• 年卷期：0
• ISSN：1530-6992

文摘

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.