Redox Reactions at Cu,Ag/Ta2O5 Interfaces and the Effects of Ta2O5 Film Density on the Forming Process in Atomic Switch Structures

Tohru Tsuruoka, Ilia Valov, Stefan Tappertzhofen, Jan Van Den Hurk, Tsuyoshi Hasegawa, Rainer Waser, Masakazu Aono

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Cu and Ag redox reactions at the interfaces with Ta2O5 and the impact of Ta2O5 film density on the forming process of Cu,Ag/Ta2O5/Pt atomic switch structures are investigated. Cyclic voltammetry measurements revealed that under positive bias to the Cu (Ag) electrode, Cu is preferentially oxidized to Cu2+, while Ag is oxidized to Ag+ ions. Subsequent negative bias causes a reduction of oxidized Cu (Ag) ions at the interfaces. The diffusion coefficient of the Cu and Ag ions in the Ta2O5 film is estimated from the results from different bias voltage sweep rates. It is also found that the redox current is enhanced and the forming voltage of the Cu/Ta2O5/Pt cell is reduced when the density of the Ta2O5 film is decreased. This result indicates the importance of the structural properties of the matrix oxide film in understanding and controlling resistive switching behavior. Redox reactions at the Ag,Cu/Ta2O5 interfaces and the impacts of Ta2O5 film density on the electroforming process of Ag,Cu/Ta2O5/Pt structures are clarified. When the density of the Ta2O5 film is decreased, the redox current is enhanced and the forming voltage is reduced. This finding contributes to a detailed understanding and control of the resistive switching behavior of oxide-based atomic switches.

Original languageEnglish
Pages (from-to)6374-6381
Number of pages8
JournalAdvanced Functional Materials
Issue number40
Publication statusPublished - 2015 Oct 1
Externally publishedYes



  • electrochemical metallization cells
  • film density
  • gapless-type atomic switch
  • oxides
  • redox reaction

ASJC Scopus subject areas

  • Biomaterials
  • Electrochemistry
  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

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