Molecular Beam Epitaxy of KTaO${}_3$

Abstract

Strain-engineering is a powerful means to tune the polar, structural, and electronic instabilities of incipient ferroelectrics. KTaO3 is near a polar instability and shows anisotropic superconductivity in electron-doped samples. Here, we demonstrate growth of high quality KTaO3 thin films by molecular-beam epitaxy. Tantalum was provided by both a suboxide source emanating a TaO2 flux from Ta2O5 contained in a conventional effusion cell as well as an electron-beam-heated tantalum source. Excess potassium and a combination of ozone and oxygen (10 \% O3 + 90 \% O2) were simultaneously supplied with the TaO${}_2$ (or tantalum) molecular beams to grow the KTaO${}_3$ films. Laue fringes suggest that the films are smooth with an abrupt film/substrate interface. Cross-sectional scanning transmission electron microscopy does not show any extended defects and confirms that the films have an atomically abrupt interface with the substrate. Atomic force microscopy reveals atomic steps at the surface of the grown films. Reciprocal space mapping demonstrates that the films, when sufficiently thin, are coherently strained to the SrTiO${}_3$ (001) and GdScO${}_3$ (110) substrates.

References in corpus (10)

• Discovery of two-dimensional anisotropic superconductivity at KTaO${}_3$ (111) interfaces
• Two-dimensional superconductivity at the surfaces of KTaO3 gated with ionic liquid
• Planar Hall Effect and Anisotropic Magnetoresistance in a polar-polar interface of LaVO${}_3$-KTaO${}_3$ with strong spin-orbit coupling
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• Alleviating polarity-conflict at the heterointerfaces of KTaO${}_3$/GdScO${}_3$ polar complex-oxides
• Coexistence of superconductivity and weak anti-localization at KTaO3 (111) interfaces
• Oxygen vacancy-induced anomalous Hall effect in a nominally non-magnetic oxide
• Control of polymorphism during epitaxial growth of hyperferroelectric candidate LiZnSb on GaSb (111)B

Cited by in corpus (4)

• Enhanced Critical Field of Superconductivity at an Oxide Interface
• Advances in Complex Oxide Quantum Materials Through New Approaches to Molecular Beam Epitaxy
• Spin-to-charge conversion at KTaO3(111) interfaces
• KTaO3(001) Preparation Methods in Vacuum: Effects on Surface Stoichiometry, Crystallography, and in-gap States