Epitaxial growth of perovskite oxide films facilitated by oxygen vacancies

Single-crystal epitaxial films of technologically important and scientifically intriguing multifunctional ABO 3 perovskite-type metal oxides are essential for advanced applications and understanding of these materials. In such films, a film-substrate misfit strain enables unprecedented crystal phase...

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Bibliographic Details
Published in:Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2021-01, Vol.9 (5), p.1693-17
Main Authors: Tyunina, M, Rusevich, L. L, Kotomin, E. A, Pacherova, O, Kocourek, T, Dejneka, A
Format: Article
Language:English
Subjects:
Crystallography
Epitaxial growth
Hypoxia
Lattice strain
Lattice vacancies
Metal oxides
Oxide coatings
Oxygen
Perovskites
Single crystals
Stresses
Strontium titanates
Substrates
Thin films
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Summary:Single-crystal epitaxial films of technologically important and scientifically intriguing multifunctional ABO 3 perovskite-type metal oxides are essential for advanced applications and understanding of these materials. In such films, a film-substrate misfit strain enables unprecedented crystal phases and unique properties that are not available in their bulk counterparts. However, the prerequisite growth of strained epitaxial films is fundamentally restricted by misfit relaxation. Here we demonstrate that introduction of a small oxygen deficiency concurrently stabilizes epitaxy and increases lattice strain in thin films of archetypal perovskite oxide SrTiO 3 . By combining experimental and theoretical methods, we found that lattice distortions around oxygen vacancies lead to anisotropic local stresses, which interact with the misfit strain in epitaxial films. Consequently, specific crystallographic alignments of the stresses are energetically favorable and can facilitate epitaxial growth of strained films. Because anisotropic oxygen-vacancy stresses are inherent to perovskite-type and many other oxides, we anticipate that the disclosed phenomenon of epitaxial stabilization by oxygen vacancies is relevant for a very broad range of functional oxides. Anisotropic elastic dipoles of oxygen vacancies interact with substrate-induced misfit strain in epitaxial oxide films. This interaction leads to specific spatial alignment of the dipoles that facilitates coherent growth.
ISSN:2050-7526
2050-7534
DOI:10.1039/d0tc05750a