Volatile two-dimensional electron gas in ultrathin BaTiO3 films

Peter Lutz, Simon Moser, Vedran Jovic, Young Jun Chang, Roland J. Koch, Søren Ulstrup, Ji Seop Oh, Luca Moreschini, Sara Fatale, Marco Grioni, Chris Jozwiak, Aaron Bostwick, Eli Rotenberg, Hendrik Bentmann, Friedrich Reinert

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


We investigate the metallic surface state in ultrathin films of BaTiO3 by angle-resolved photoemission spectroscopy. We find Fermi-surface contours derived from the Ti 3dt2g conduction band, similar as in SrTiO3 but with broader spectral features due to enhanced quasiparticle scattering. Oxygen vacancies created in the x-ray beam spot allow for reversible in situ doping control up to surface carrier densities as high as 1014cm-2, but vacancy migration into the subsurface at T≥285K quenches the surface state. Our analysis suggests that the charge state of oxygen vacancies in ultrathin films is predominantly 2+, which limits charge-carrier trapping and the formation of localized defect states.

Original languageEnglish
Article number094411
JournalPhysical Review Materials
Issue number9
StatePublished - 28 Sep 2018


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