Epitaxial Ferroelectric Hf0.5Zr0.5O2 with Metallic Pyrochlore Oxide Electrodes

Zimeng Zhang, Shang Lin Hsu, Vladimir A. Stoica, Hanjong Paik, Eric Parsonnet, Alexander Qualls, Jianjun Wang, Liang Xie, Mukesh Kumari, Sujit Das, Zhinan Leng, Martin McBriarty, Roger Proksch, Alexei Gruverman, Darrell G. Schlom, Long Qing Chen, Sayeef Salahuddin, Lane W. Martin, Ramamoorthy Ramesh

Research output: Contribution to journalArticlepeer-review

Abstract

The synthesis of fully epitaxial ferroelectric Hf0.5Zr0.5O2 (HZO) thin films through the use of a conducting pyrochlore oxide electrode that acts as a structural and chemical template is reported. Such pyrochlores, exemplified by Pb2Ir2O7(PIO) and Bi2Ru2O7(BRO), exhibit metallic conductivity with room-temperature resistivity of <1 mΩ cm and are closely lattice matched to yttria-stabilized zirconia substrates as well as the HZO layers grown on top of them. Evidence for epitaxy and domain formation is established with X-ray diffraction and scanning transmission electron microscopy, which show that the c-axis of the HZO film is normal to the substrate surface. The emergence of the non-polar-monoclinic phase from the polar-orthorhombic phase is observed when the HZO film thickness is ≥≈30 nm. Thermodynamic analyses reveal the role of epitaxial strain and surface energy in stabilizing the polar phase as well as its coexistence with the non-polar-monoclinic phase as a function of film thickness.

Original languageEnglish (US)
Article number2006089
JournalAdvanced Materials
Volume33
Issue number10
DOIs
StatePublished - Mar 11 2021

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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