Quasi-Two-Dimensional Electron Gas at the Epitaxial Alumina/SrTiO3 Interface: Control of Oxygen Vacancies
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 ∼1013 cm−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.
- Author (aut): Kormondy, Kristy J.
- Author (aut): Posadas, Agham B.
- Author (aut): Ngo, Thong Q.
- Author (aut): Lu, Sirong
- Author (aut): Goble, Nicholas
- Author (aut): Jordan-Sweet, Jean
- Author (aut): Gao, Xuan P. A.
- Author (aut): Smith, David
- Author (aut): McCartney, Martha
- Author (aut): Ekerdt, John G.
- Author (aut): Demkov, Alexander A.
- Contributor (ctb): College of Liberal Arts and Sciences