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The Vacancy‐Induced Electronic Structure of the SrTiO 3−δ Surface
Author(s) -
Cook Seyoung,
Dylla Maxwell T.,
Rosenberg Richard A.,
Mansley Zachary R.,
Snyder G. Jeffrey,
Marks Laurence D.,
Fong Dillon D.
Publication year - 2019
Publication title -
advanced electronic materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.25
H-Index - 56
ISSN - 2199-160X
DOI - 10.1002/aelm.201800460
Subject(s) - band bending , strontium titanate , materials science , condensed matter physics , fermi level , electronic structure , vacancy defect , fermi gas , electronic band structure , electron , resistive touchscreen , surface states , effective mass (spring–mass system) , surface (topology) , nanotechnology , thin film , physics , optoelectronics , engineering , quantum mechanics , electrical engineering , geometry , mathematics
The emergence of a 2D electron gas (2DEG) on the (001) surface of oxygen‐deficient strontium titanate (SrTiO 3−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 SrTiO 3−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 SrTiO 3 .