The Vacancy-Induced Electronic Structure of the SrTiO3−δ Surface

Seyoung Cook, Maxwell T. Dylla, Richard A. Rosenberg, Zachary R. Mansley, G. Jeffrey Snyder, Laurence D. Marks, Dillon D. Fong*

*Corresponding author for this work

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

The emergence of a 2D electron gas (2DEG) on the (001) surface of oxygen-deficient strontium titanate (SrTiO3−δ) is investigated. Using in situ soft X-ray spectroscopy and effective mass modeling, a series of quantitative band diagrams are developed to describe the evolution of near-surface and bulk carrier concentrations, downward band bending, and Fermi level along a lateral gradient of oxygen vacancies formed on SrTiO3−δ by direct-current resistive heating under ultrahigh vacuum conditions. Electrons are accumulated over a 3 nm region near the surface, confined within a potential well with saturated 300 meV downward band bending. The relation between Fermi levels and carrier concentrations near the surface suggests the density of states near the surface is much lower than the bulk density of states, which is consistent with the quantum-confined subbands of a 2DEG. The quantitative relationship between the surface and bulk electronic structures developed in this work provides a guide for precise engineering of the oxygen-vacancy-induced 2DEG in SrTiO3.

Original languageEnglish (US)
Article number1800460
JournalAdvanced Electronic Materials
Volume5
Issue number1
DOIs
StatePublished - Jan 2019

Keywords

  • SrTiO surface
  • effective mass modeling
  • electronic structure
  • in-situ x-ray spectroscopy
  • oxygen vacancies

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials

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