Non-Radiative Luminescence Decay with Self-Trapped Hole Migration in Strontium Titanate: Interplay between Optical and Transport Properties
A novel model for the non-radiative decay of self-trapped excitons (STEs) in the advanced functional oxide SrTiO3 is proposed and supported by experimental observations. The study is based on the initial ionoluminescence stage for STE emission at 2.5 eV, and its dependence on temperature and electronic excitation rate under energetic heavy-ion irradiation. For all temperatures, this initial stage reaches rapidly a quasi-steady level, and then decreases as induced-structural damage increases. The quasi-steady luminescence exhibits a linear dependence on the excitation rate, suggesting a constant efficiency for STEs formation. An activation energy of 55 meV, essentially independent of the incident ion mass and energy of projectile-ion, is deduced from an Arrhenius-type relationship with irradiation temperature. This energy is in good agreement with experimental values, measured for non-radiative STE decay under ns-laser pulse excitation, and reasonably consistent with density functional theory calculations for migration of self-trapped holes (STHs) described by a small-polaron adiabatic hopping model. A new mechanism dealing with a non-radiative contribution to the STE transition is discussed, consisting of STH migration through thermally-activated hopping and annihilation with the STE-electron. Luminescence kinetics from the chromium intrinsic impurity strongly supports this model, being consistent with the annihilation of Cr3+ centers through recombination with migrating STHs.
M. L. Crespillo et al., "Non-Radiative Luminescence Decay with Self-Trapped Hole Migration in Strontium Titanate: Interplay between Optical and Transport Properties," Applied Materials Today, vol. 23, Elsevier, Jun 2021.
The definitive version is available at https://doi.org/10.1016/j.apmt.2021.101041
Nuclear Engineering and Radiation Science
Keywords and Phrases
Activation Energy; Luminescence; Self-Trapped Excitons; Self-Trapped Holes; Strontium Titanate
International Standard Serial Number (ISSN)
Article - Journal
© 2021 Elsevier, All rights reserved.
01 Jun 2021