Abstract
We investigate the metallic surface state in ultrathin films of by angle-resolved photoemission spectroscopy. We find Fermi-surface contours derived from the Ti conduction band, similar as in 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 , but vacancy migration into the subsurface at quenches the surface state. Our analysis suggests that the charge state of oxygen vacancies in ultrathin films is predominantly , which limits charge-carrier trapping and the formation of localized defect states.
- Received 10 May 2017
- Revised 9 July 2017
DOI:https://doi.org/10.1103/PhysRevMaterials.2.094411
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