Origin of the 2D electron gas at the SrTiO<sub>3</sub> surface

ORAL

Abstract

Since the discovery of the 2D electron gas (2DEG) at the SrTiO3 (001) surface in 2011 via angle-resolved photoemission spectroscopy (ARPES), there have been several theories proposing its origin. In separate studies, scientists have demonstrated that many of reconstructions at the SrTiO3 surface are TiO2-rich. Others using X-ray photoelectron spectroscopy (XPS) have demonstrated the presence of oxygen vacancies at the surface, correlating them with a surface electronic state (in-gap state, IGS). Here we employed in situ synchrotron X-ray methods during growth by molecular beam epitaxy (MBE), ARPES, and XPS to study the origin of the 2DEG and its evolution. We discover that the 2DEG only appears when the surface has TiO2 double layer structure [1], for the first time linking the atomic surface structure to its 2DEG electronic states. Interestingly, by deposition of single layer of SrO or the subsequent growth of a TiO2 monolayer, we are able to completely control the disappearance/reappearance of both the 2DEG and the IGS, potentially providing a means of manipulating 2DEG-behavior in oxide electronics.

[1] S. Cook et al., Sci. Adv. 5, eaav0764 (2019).

*Work supported by the Department of Energy, Office of Science, Basic Energy Sciences under contract no. DE-AC02-06CH11357.

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Presenters

  • Xi Yan

    • Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
    • Materials Science Division, Argonne National Laboratory
    • Materials Science Division, Argonne National Lab

Authors

  • Xi Yan

    • Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
    • Materials Science Division, Argonne National Laboratory
    • Materials Science Division, Argonne National Lab

  • Friederike Wrobel

    • Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
    • Materials Science Division, Argonne National Lab

  • Hawoong Hong

    • Argonne National Laboratory
    • Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
    • Advanced Photon Source

  • Jirong Sun

    • Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
    • Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences
    • Institute of Physics

  • Jessica L McChesney

    • Argonne National Laboratory, Advanced Photon Source
    • Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
    • Argonne National Laboratory

  • Hua Zhou

    • X-ray Science Division, Advanced Photon Source,, Argonne National Laboratory
    • Advanced Photon Source, Argonne National Laboratory
    • Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
    • Argonne National Laboratory
    • Advanced Photon Source, Argonne National Lab
    • Advanced Photon Source

  • Dillon D Fong

    • Argonne National Laboratory
    • Materials Science Division, Argonne National Laboratory
    • Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
    • Materials Science Division, Argonne National Lab