Freestanding epitaxial SrTiO3 nanomembranes via remote epitaxy using hybrid molecular beam epitaxy

Hyojin Yoon; Tristan K Truttmann; Fengdeng Liu; Bethany E Matthews; Sooho Choo; Qun Su; Vivek Saraswat; Sebastian Manzo; Michael S Arnold; Mark E Bowden; Jason K Kawasaki; Steven J Koester; Steven R Spurgeon; Scott A Chambers; Bharat Jalan

doi:10.1126/sciadv.add5328

Freestanding epitaxial SrTiO₃ nanomembranes via remote epitaxy using hybrid molecular beam epitaxy

Sci Adv. 2022 Dec 23;8(51):eadd5328. doi: 10.1126/sciadv.add5328. Epub 2022 Dec 23.

Authors

Affiliations

¹ Department of Chemical Engineering and Materials Science, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA.
² Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland,, WA 99352, USA.
³ Department of Electrical and Computer Engineering, University of Minnesota, Twin Cities, Minneapolis, MN 55455, USA.
⁴ Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA.
⁵ Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352, USA.
⁶ Department of Physics, University of Washington, Seattle, WA 98195, USA.
⁷ Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA.

Abstract

The epitaxial growth of functional oxides using a substrate with a graphene layer is a highly desirable method for improving structural quality and obtaining freestanding epitaxial nanomembranes for scientific study, applications, and economical reuse of substrates. However, the aggressive oxidizing conditions typically used in growing epitaxial oxides can damage graphene. Here, we demonstrate the successful use of hybrid molecular beam epitaxy for SrTiO₃ growth that does not require an independent oxygen source, thus avoiding graphene damage. This approach produces epitaxial films with self-regulating cation stoichiometry. Furthermore, the film (46-nm-thick SrTiO₃) can be exfoliated and transferred to foreign substrates. These results open the door to future studies of previously unattainable freestanding oxide nanomembranes grown in an adsorption-controlled manner by hybrid molecular beam epitaxy. This approach has potentially important implications for the commercial application of perovskite oxides in flexible electronics and as a dielectric in van der Waals thin-film electronics.