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

doi:10.1103/PhysRevMaterials.2.094411

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

Department of Physics

Research output: Contribution to journal › Article › peer-review

8 Scopus citations

Abstract

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 language	English
Article number	094411
Journal	Physical Review Materials
Volume	2
Issue number	9
DOIs	https://doi.org/10.1103/PhysRevMaterials.2.094411
State	Published - 28 Sep 2018

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10.1103/PhysRevMaterials.2.094411

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title = "Volatile two-dimensional electron gas in ultrathin BaTiO3 films",

abstract = "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.",

author = "Peter Lutz and Simon Moser and Vedran Jovic and Chang, {Young Jun} and Koch, {Roland J.} and S{\o}ren Ulstrup and Oh, {Ji Seop} and Luca Moreschini and Sara Fatale and Marco Grioni and Chris Jozwiak and Aaron Bostwick and Eli Rotenberg and Hendrik Bentmann and Friedrich Reinert",

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doi = "10.1103/PhysRevMaterials.2.094411",

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T1 - Volatile two-dimensional electron gas in ultrathin BaTiO3 films

AU - Lutz, Peter

AU - Moser, Simon

AU - Jovic, Vedran

AU - Chang, Young Jun

AU - Koch, Roland J.

AU - Ulstrup, Søren

AU - Oh, Ji Seop

AU - Moreschini, Luca

AU - Fatale, Sara

AU - Grioni, Marco

AU - Jozwiak, Chris

AU - Bostwick, Aaron

AU - Rotenberg, Eli

AU - Bentmann, Hendrik

AU - Reinert, Friedrich

PY - 2018/9/28

Y1 - 2018/9/28

N2 - 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.

AB - 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.

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Volatile two-dimensional electron gas in ultrathin BaTiO3 films

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