Observation of filament formation process of Cu/HfO 2/Pt ReRAM structure by hard x-ray photoelectron spectroscopy under bias operation

Takahiro Nagata, Masamitsu Haemori, Yoshiyuki Yamashita, Hideki Yoshikawa, Keisuke Kobayashi, Toyohiro Chikyow

Research output: Contribution to journalReview articlepeer-review

4 Citations (Scopus)

Abstract

We have demonstrated resistance switching using polycrystalline HfO 2 film with a Cu top electrode for nonvolatile memory applications and revealed the Cu diffusion into the HfO 2 layer during the filament formation process. Resistive switching was clearly observed in the Cu/HfO 2/Pt structure by performing a current-voltage measurement. The current step from a high-resistive state to a low-resistive state was of the order of 10 3-10 4 Ω, which provided a sufficient on/off ratio for use as a switching device. The filament formation process was investigated by employing hard x-ray photoelectron spectroscopy under bias operation. The application of a bias to the structure reduced the Cu 2O state at the interface and the intensity ratio of Cu 2p 3/2/Hf 3d 5/2, providing evidence of Cu 2O reduction and Cu diffusion into the HfO 2 layer. These results also provide evidence that the resistance switching of the Cu/HfO 2/Pt structure originates in a solid electrolyte (nanoionics model) containing Cu ions.

Original languageEnglish
Pages (from-to)869-878
Number of pages10
JournalJournal of Materials Research
Volume27
Issue number6
DOIs
Publication statusPublished - 2012 Mar 28
Externally publishedYes

Keywords

  • Memory
  • Oxide
  • X-ray photoelectron spectroscopy

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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