2014/07/25 by Harald O. Jeschke, Harald O Jeschke, Juan Shen +2 · 53 citations
Engineering · Materials Science · Physics and Astronomy · #Cluster (spacecraft) #Density functional theory #Electron #Electronic and Structural Properties of Oxides #Electronic structure #Ferroelectric and Piezoelectric Materials #Lattice (music) #Oxygen #Population #Semiconductor materials and devices #Strontium titanate #Vacancy defect #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1088/1367-2630/17/2/023034
published in New Journal of Physics 17(2), 023034 (IOP Publishing) · 6 pages, 7 figures
arxiv created 2014/07/25 · openalex publication_date 2015/02/10 · arxiv updated 2015/06/22 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
Oxygen vacancies in strontium titanate surfaces (SrTiO 3 ) have been linked to the presence of a two-dimensional electron gas with unique behavior. We perform a detailed density functional theory study of the lattice and electronic structure of SrTiO 3 slabs with multiple oxygen vacancies, with a main focus on two vacancies near a titanium dioxide terminated SrTiO 3 surface. We conclude based on total energies that the two vacancies preferably inhabit the first two layers, i.e. they cluster vertically, while in the direction parallel to the surface, the vacancies show a weak tendency towards equal spacing. Analysis of the nonmagnetic electronic structure indicates that oxygen defects in the surface TiO 2 layer lead to population of Ti states and thus itinerancy of the electrons donated by the oxygen vacancy. In contrast, electrons from subsurface oxygen vacancies populate Ti e g states and remain localized on the two Ti ions neighboring the vacancy. We find that both the formation of a bound oxygen-vacancy state composed of hybridized Ti 3 e g and 4p states neighboring the oxygen vacancy as well as the elastic deformation after extracting oxygen contribute to the stabilization of the in-gap state.