Germanium dioxide: A new rutile substrate for epitaxial film growth

Sieun Chae, Lucas A. Pressley, Hanjong Paik, Jiseok Gim, Don Werder, Berit H. Goodge, Lena F. Kourkoutis, Robert Hovden, Tyrel M. McQueen, Emmanouil Kioupakis, John T. Heron

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Rutile compounds have exotic functional properties that can be applied for various electronic applications; however, the limited availability of epitaxial substrates has restricted the study of rutile thin films to a limited range of lattice parameters. Here, rutile GeO2 is demonstrated as a new rutile substrate with lattice parameters of a = 4.398 Å and c = 2.863 Å. Rutile GeO2 single crystals up to 4 mm in size are grown by the flux method. X-ray diffraction reveals high crystallinity with a rocking curve having a full width half-maximum of 0.0572°. After mechanical polishing, a surface roughness of less than 0.1 nm was obtained, and reflection high-energy electron diffraction shows a crystalline surface. Finally, epitaxial growth of (110)-oriented TiO2 thin films on GeO2 substrates was demonstrated using molecular beam epitaxy. Templated by rutile GeO2 substrates, our findings open the possibility of stabilizing new rutile thin films and strain states for the tuning of physical properties.

Original languageEnglish
Article number050401
JournalJournal of Vacuum Science and Technology, Part A: Vacuum, Surfaces and Films
Volume40
Issue number5
DOIs
StatePublished - Sep 1 2022
Externally publishedYes

Funding

This work was supported by the National Science Foundation [Platform for the Accelerated Realization, Analysis, and Discovery of Interface Materials (PARADIM)] under Cooperative Agreement No. DMR-2039380. S.C. acknowledges support from Rackham Predoctoral Fellowship. This work made use of the Cornell Center for Materials Research (CCMR) Shared Facilities, which are supported through the NSF MRSEC Program (No. DMR-1719875). The Thermo Fisher Helios G4 UX FIB was acquired with support by NSF No. DMR-1539918. The Thermo Fisher Spectra 300 X-CFEG was acquired with support from PARADIM and Cornell University.

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