Atomic-scale Structural and Electronic Properties of SrTiO3/GaAs Interfaces: A Combined STEM-EELS and First-principles Study

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dc.contributor.authorHong, Liang
dc.contributor.authorBhatnagar, Kunal
dc.contributor.authorDroopad, Ravi
dc.contributor.authorKlie, Robert
dc.contributor.authorOgut, Serdar
dc.date.accessioned2020-04-20T21:55:29Z
dc.date.available2020-04-20T21:55:29Z
dc.date.issued2017-07
dc.description.abstractThe electronic properties of epitaxial oxide thin films grown on compound semiconductors are largely determined by the interfacial atomic structure, as well as the thermodynamic conditions during synthesis. Ferroelectric polarization and Fermi-level pinning in SrTiO3 films have been attributed to the presence of oxygen vacancies at the oxide/semiconductor interface. Here, we present scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy analyses of GaAs films grown on SrTiO3 combined with first-principles calculations to determine the atomic and electronic structures of the SrTiO3/ GaAs interfaces. An atomically abrupt SrO/As interface is observed and the interfacial SrO layer is found to be O-deficient. First-principles density functional theory (DFT) calculations show SrO/Ga and Sr/As interfaces are favorable under O-rich and O-poor conditions, respectively. The SrO/Ga interface is reconstructed via the formation of Ga-Ga dimers while the Sr/As interface is abrupt and consistent with the experiment. DFT calculations further reveal that intrinsic two-dimensional electron gas (2DEG) forms in both SrO/Ga and Sr/As interfaces, and the Fermi level is pinned to the localized 2DEG states. Interfacial O vacancies can enhance the 2DEG density while it is possible for Ga/As vacancies to unpin the Fermi level from the 2DEG states.
dc.description.departmentEngineering
dc.formatText
dc.format.extent11 pages
dc.format.medium1 file (.pdf)
dc.identifier.citationHong, L., Bhatnagar, K., Droopad, R., Klie, R. F., & Ogut, S. (2017). Atomic-scale structural and electronic properties of SrTiO3/GaAs interfaces: A combined STEM-EELS and first-principles study. Physical Review B, 96(3).
dc.identifier.doihttps://doi.org/10.1103/PhysRevB.96.035311
dc.identifier.issn2469-9950
dc.identifier.urihttps://hdl.handle.net/10877/9656
dc.language.isoen
dc.publisherAmerican Physical Society
dc.rights.holder©2017 American Physical Society.
dc.sourcePhysical Review B, 2017, Vol. 96, No. 3.
dc.subjectepitaxial oxide thin films
dc.subjectcompound semiconductors
dc.subjectscanning transmission electron microscopy
dc.subjectSrTiO3 / GaAs interfaces
dc.titleAtomic-scale Structural and Electronic Properties of SrTiO3/GaAs Interfaces: A Combined STEM-EELS and First-principles Study
dc.typeArticle

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