Mesostructured HfO2/Al2O3 Composite Thin Films with Reduced Leakage Current for Ion-Conducting Devices

Mohamed Barakat Zakaria, Takahiro Nagata, Toyohiro Chikyow

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Mesoporous hafnium dioxide (HfO2) thin films (around 20 nm thick) were fabricated by a sol-gel-based spin-coating process, followed by an annealing process at 600 °C to realize the ion-conducting media for the ionics (e.g., Na+ and K+ for rechargeable ion batteries). Another film of aluminum metal (10 nm thick) was deposited by direct current sputtering to soak into the mesopores. A monitored thermal treatment process at 500 °C in the air yields mesostructured HfO2/Al2O3 composite thin films. However, aluminum dioxide (Al2O3) is formed during annealing as an insulating film to reduce the leakage current while retaining the ionic conductivity. The obtained mesostructured HfO2/Al2O3 films show a leakage current at 3.2 × 10-9 A cm-2, which is significantly smaller than that of the mesoporous HfO2 film (1.37 × 10-5 A cm-2) or HfO2/Al film (0.037 A cm-2) at a bias voltage of 1.0 V, which is enough for ion conduction. In the meantime, among all the thin films, the mesostructured HfO2/Al2O3 composite thin films display the smallest Nyquist arc diameter in 1.0 M KOH electrolyte, implying a lower impedance at the electrode/electrolyte interface and reflecting a better ion diffusion and movement.

Original languageEnglish
Pages (from-to)14680-14687
Number of pages8
JournalACS Omega
Volume4
Issue number12
DOIs
Publication statusPublished - 2019 Sep 17

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)

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