Quasi-two-dimensional electron gas at the epitaxial alumina/SrTiO3 interface: Control of oxygen vacancies

Kristy J. Kormondy, Agham B. Posadas, Thong Q. Ngo, Sirong Lu, Nicholas Goble, Jean Jordan-Sweet, Xuan P A Gao, David Smith, Martha McCartney, John G. Ekerdt, Alexander A. Demkov

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34 Scopus citations


In this paper, we report on the highly conductive layer formed at the crystalline γ-alumina/SrTiO3 interface, which is attributed to oxygen vacancies. We describe the structure of thin γ-alumina layers deposited by molecular beam epitaxy on SrTiO3 (001) at growth temperatures in the range of 400-800 °C, as determined by reflection-high-energy electron diffraction, x-ray diffraction, and high-resolution electron microscopy. In situ x-ray photoelectron spectroscopy was used to confirm the presence of the oxygen-deficient layer. Electrical characterization indicates sheet carrier densities of ∼1013cm-2 at room temperature for the sample deposited at 700 °C, with a maximum electron Hall mobility of 3100 cm2V-1s-1 at 3.2 K and room temperature mobility of 22 cm2V-1s-1. Annealing in oxygen is found to reduce the carrier density and turn a conductive sample into an insulator.

Original languageEnglish (US)
Article number095303
JournalJournal of Applied Physics
Issue number9
StatePublished - Mar 7 2015

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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