Open AccessDefect accommodation in off-stoichiometric (SrTiO3)nSrO Ruddlesden–Popper superlattices studied with positron annihilation spectroscopy
Author(s) -
Natalie M. Dawley,
Berit H. Goodge,
Werner Egger,
Matthew R. Barone,
Lena F. Kourkoutis,
D. J. Keeble,
Darrell G. Schlom
Publication year - 2020
Publication title -
applied physics letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 442
eISSN - 1077-3118
pISSN - 0003-6951
DOI - 10.1063/5.0011136
Subject(s) - stoichiometry , positron annihilation spectroscopy , materials science , electron energy loss spectroscopy , spectroscopy , vacancy defect , condensed matter physics , superlattice , dielectric , transmission electron microscopy , scanning transmission electron microscopy , electron , positron , chemistry , positron annihilation , nanotechnology , optoelectronics , physics , nuclear physics , quantum mechanics
The low dielectric loss underlying the record performance of strained (SrTiO3)nSrO Ruddlesden–Popper films as tunable microwave dielectrics was postulated to arise from (SrO)2 faults accommodating local non-stoichiometric defects. Here, we explore the effect of non-stoichiometry on (SrTiO3)nSrO using positron annihilation lifetime spectroscopy on a composition series of 300 nm thick n = 6 (Sr1+δTiO3)nSrO thin films. These films show titanium-site vacancies across the stoichiometry series, with evidence that TiOx vacancy complexes dominate. Little change in defect populations is observed across the series, indicating the ability of Ruddlesden–Popper phases to accommodate ± 5% off-stoichiometry. This ability for defect accommodation is corroborated by scanning transmission electron microscopy with electron energy loss spectroscopy.
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