Defect accommodation in off-stoichiometric (SrTiO3)nSrO Ruddlesden–Popper superlattices studied with positron annihilation spectroscopy
Abstract
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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Aug 10, 2020
- Source ID
- 10.1063/5.0011136
Entities
People
- Berit H. Goodge
- Darrell G. Schlom
- David J. Keeble
- Lena F Kourkoutis
- Matthew R. Barone
- Natalie M. Dawley
- Werner Egger
Organizations
- Cornell University
- Leibniz Institute for Crystal Growth
- National Science Foundation
- United States Department of Defense
- United States Department of Energy
- University of Dundee