Stoichiometry-dependent surface electronic structure of SrTiO3films grown by hybrid molecular beam epitaxy

Dooyong Lee; Fengdeng Liu; Tristan K Truttmann; Scott A. Chambers; Bharat Jalan

doi:10.1063/5.0082636

Stoichiometry-dependent surface electronic structure of SrTiO₃films grown by hybrid molecular beam epitaxy

Dooyong Lee, Fengdeng Liu, Tristan K Truttmann, Scott A. Chambers, Bharat Jalan

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

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Abstract

We investigate the surface electronic structure of SrTiO3 (STO) films grown by a hybrid molecular beam epitaxy that are both stoichiometric and nonstoichiometric by means of x-ray photoelectron spectroscopy and electron energy loss spectroscopy. Increasing the fraction of the surface that is terminated with an SrO layer is correlated with a decrease in the chemical potential whereby the valence band maximum moves closer to the Fermi level, but without a significant change in the bandgap. Inasmuch as SrO-terminated STO (001) has previously been shown to act as an electron scavenger in which carriers from the bulk are trapped, we argue that the high fraction of SrO in the terminal layer is what lowers the chemical potential in Sr-rich STO. Our experimental results provide important insights into various physical phenomena that can occur on STO (001) surfaces and their effect on bulk electronic properties.

Original language	English (US)
Article number	121604
Journal	Applied Physics Letters
Volume	120
Issue number	12
DOIs	https://doi.org/10.1063/5.0082636
State	Published - Mar 21 2022

Bibliographical note

Funding Information:
This work was primarily supported by the U.S. Department of Energy through No. DE-SC002021. F.L. acknowledges support from the Air Force Office of Scientific Research (AFOSR) through Grant Nos. FA9550-19-1-0245 and FA9550-21-1-0025 and partially through NSF No. DMR-1741801. Parts of this work were carried out at the Characterization Facility, University of Minnesota, which receives partial support from National Science Foundation (NSF) through the Materials Research Science and Engineering Center (MRSEC) program under Award No. DMR-2011401. The work at Pacific Northwest National Laboratory (PNNL) was supported by the U.S. Department of Energy, Office of Science, Division of Materials Sciences and Engineering under Award No. 10122 to PNNL.

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abstract = "We investigate the surface electronic structure of SrTiO3 (STO) films grown by a hybrid molecular beam epitaxy that are both stoichiometric and nonstoichiometric by means of x-ray photoelectron spectroscopy and electron energy loss spectroscopy. Increasing the fraction of the surface that is terminated with an SrO layer is correlated with a decrease in the chemical potential whereby the valence band maximum moves closer to the Fermi level, but without a significant change in the bandgap. Inasmuch as SrO-terminated STO (001) has previously been shown to act as an electron scavenger in which carriers from the bulk are trapped, we argue that the high fraction of SrO in the terminal layer is what lowers the chemical potential in Sr-rich STO. Our experimental results provide important insights into various physical phenomena that can occur on STO (001) surfaces and their effect on bulk electronic properties.",

author = "Dooyong Lee and Fengdeng Liu and Truttmann, {Tristan K} and Chambers, {Scott A.} and Bharat Jalan",

note = "Funding Information: This work was primarily supported by the U.S. Department of Energy through No. DE-SC002021. F.L. acknowledges support from the Air Force Office of Scientific Research (AFOSR) through Grant Nos. FA9550-19-1-0245 and FA9550-21-1-0025 and partially through NSF No. DMR-1741801. Parts of this work were carried out at the Characterization Facility, University of Minnesota, which receives partial support from National Science Foundation (NSF) through the Materials Research Science and Engineering Center (MRSEC) program under Award No. DMR-2011401. The work at Pacific Northwest National Laboratory (PNNL) was supported by the U.S. Department of Energy, Office of Science, Division of Materials Sciences and Engineering under Award No. 10122 to PNNL. Publisher Copyright: {\textcopyright} 2022 Author(s).",

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N2 - We investigate the surface electronic structure of SrTiO3 (STO) films grown by a hybrid molecular beam epitaxy that are both stoichiometric and nonstoichiometric by means of x-ray photoelectron spectroscopy and electron energy loss spectroscopy. Increasing the fraction of the surface that is terminated with an SrO layer is correlated with a decrease in the chemical potential whereby the valence band maximum moves closer to the Fermi level, but without a significant change in the bandgap. Inasmuch as SrO-terminated STO (001) has previously been shown to act as an electron scavenger in which carriers from the bulk are trapped, we argue that the high fraction of SrO in the terminal layer is what lowers the chemical potential in Sr-rich STO. Our experimental results provide important insights into various physical phenomena that can occur on STO (001) surfaces and their effect on bulk electronic properties.

AB - We investigate the surface electronic structure of SrTiO3 (STO) films grown by a hybrid molecular beam epitaxy that are both stoichiometric and nonstoichiometric by means of x-ray photoelectron spectroscopy and electron energy loss spectroscopy. Increasing the fraction of the surface that is terminated with an SrO layer is correlated with a decrease in the chemical potential whereby the valence band maximum moves closer to the Fermi level, but without a significant change in the bandgap. Inasmuch as SrO-terminated STO (001) has previously been shown to act as an electron scavenger in which carriers from the bulk are trapped, we argue that the high fraction of SrO in the terminal layer is what lowers the chemical potential in Sr-rich STO. Our experimental results provide important insights into various physical phenomena that can occur on STO (001) surfaces and their effect on bulk electronic properties.

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Stoichiometry-dependent surface electronic structure of SrTiO₃films grown by hybrid molecular beam epitaxy

Abstract

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IRG-1: Ionic Control of Materials

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Stoichiometry-dependent surface electronic structure of SrTiO3films grown by hybrid molecular beam epitaxy

Abstract

Bibliographical note

MRSEC Support

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IRG-1: Ionic Control of Materials

University of Minnesota Materials Research Science and Engineering Center (DMR-2011401)

Cite this

Stoichiometry-dependent surface electronic structure of SrTiO₃films grown by hybrid molecular beam epitaxy