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

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

doi:10.1063/1.4913860

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

Journal Article · Thu Mar 05 00:00:00 EST 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4913860· OSTI ID:1229307

Kormondy, Kristy J. ^[1]; Posadas, Agham B. ^[1]; Ngo, Thong Q. ^[1]; Lu, Sirong ^[2]; Goble, Nicholas ^[3]; Jordan-Sweet, Jean ^[4]; Gao, Xuan P. A. ^[3]; Smith, David J. ^[2]; McCartney, Martha R. ^[2]; Ekerdt, John G. ^[1]; Demkov, Alexander A. ^[1]

Univ. of Texas, Austin, TX (United States)
Arizona State Univ., Tempe, AZ (United States)
Case Western Reserve Univ., Cleveland, OH (United States)
IBM T.J. Watson Research Center, Yorktown Heights, NY (United States)

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. In conclusion, annealing in oxygen is found to reduce the carrier density and turn a conductive sample into an insulator.

View Accepted Manuscript (DOE)

Research Organization:: Brookhaven National Laboratory (BNL), Upton, NY (United States)

Sponsoring Organization:: Air Force Office of Scientific Research (AFOSR); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)

Grant/Contract Number:: AC02-98CH10886

OSTI ID:: 1229307

Alternate ID(s):: OSTI ID: 22413227

Report Number(s):: BNL--111382-2015-JA

Journal Information:: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 9 Vol. 117; ISSN 0021-8979

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

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Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Crystallographic defects
Electron diffraction
Electronic transport
Epitaxy
Hall effect
High-resolution electron microscopy
Transition metal oxides
Two-dimensional electron gas
X-ray diffraction
X-ray photoelectron spectroscopy