Role and Optimization of the Active Oxide Layer in TiO2-Based RRAM

Anna Regoutz*, Isha Gupta, Alexantrou Serb, Ali Khiat, Francesco Borgatti, Tien Lin Lee, Christoph Schlueter, Piero Torelli, Benoit Gobaut, Mark Light, Daniela Carta, Stuart Pearce, Giancarlo Panaccione, Themistoklis Prodromakis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

TiO2 is commonly used as the active switching layer in resistive random access memory. The electrical characteristics of these devices are directly related to the fundamental conditions inside the TiO2 layer and at the interfaces between it and the surrounding electrodes. However, it is complex to disentangle the effects of film "bulk" properties and interface phenomena. The present work uses hard X-ray photoemission spectroscopy (HAXPES) at different excitation energies to distinguish between these regimes. Changes are found to affect the entire thin film, but the most dramatic effects are confined to an interface. These changes are connected to oxygen ions moving and redistributing within the film. Based on the HAXPES results, post-deposition annealing of the TiO2 thin film was investigated as an optimisation pathway in order to reach an ideal compromise between device resistivity and lifetime. The structural and chemical changes upon annealing are investigated using X-ray absorption spectroscopy and are further supported by a range of bulk and surface sensitive characterisation methods. In summary, it is shown that the management of oxygen content and interface quality is intrinsically important to device behavior and that careful annealing procedures are a powerful device optimisation technique.

Original languageEnglish
Pages (from-to)507-513
Number of pages7
JournalAdvanced Functional Materials
Issue number4
Early online date15 Dec 2015
Publication statusPublished - 26 Jan 2016

Keywords / Materials (for Non-textual outputs)

  • annealing
  • interfaces
  • photoelectron spectroscopy
  • resistive memory
  • titanium dioxide


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