Identification of a functional point defect in SrTiO3

• DOI: 10.1103/physrevmaterials.2.060403
• Publication Date: 2018-06-21T14:26:41Z
• Authors: Daesu Lee; Hongwei Wang; Brenton A. Noesges; Thaddeus J. Asel; Jinbo Pan; Jung-Woo Lee; Qimin Yan; Leonard J. Brillson; Xifan Wu; Chang-Beom Eom
• Keywords: Cathodoluminescence; Stoichiometry

Unveiling both the presence and nature of point defects is one biggest challenges in condensed matter physics materials science. Particularly complex oxides, even a minute amount unavoidable could generate novel physical phenomena functions, such as visible light emission ferroelectricity, yet it remains elusive to clearly identify defects. Here, taking $\mathrm{SrTi}{\mathrm{O}}_{3}$ model system, we show that iterative feedback among atomic-layer- stoichiometry-controlled thin-film epitaxy, hybrid density functional theory, high-resolution cathodoluminescence spectroscopy allows for identification cationic defect, Ti antisite (${\mathrm{Ti}}_{\mathrm{Sr}}$) defect. Our measurements reveal sub-band-gap luminescence, whose spectral fine structures excellent quantitative agreement, well one-to-one correspondence, with theoretically predicted optical transitions from intrinsic ${\mathrm{Ti}}_{\mathrm{Sr}}$. Guided by theory spectroscopic results, also control cation stoichiometry, turn results good systematics spectra. Not limited ${\mathrm{Ti}}_{\mathrm{Sr}}$, this approach more reliable, self-consistent defect study, provides critical insight into microscopic picture oxides.