Quantification and mapping of elastic strains in ferroelectric [BaZrO3]xᴧ/[BaTiO3](1-x)ᴧ superlattices

• Published in: Applied surface science 2020-05, Vol.512, p.145761, Article 145761
• Main Authors: Belhadi, J., Ravaux, F., Bouyanfif, H., Jouiad, M., El Marssi, M.
• Format: Article
• Language: English
• Subjects: Epitaxial growth; Ferroelectric; Physics; Pulsed laser deposition; Strain mapping; Superlattice
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2020.145761

[Display omitted] •Ferroelectric superlattices were fabricated using Pulsed Laser Disposition.•Nanobeam diffraction at 2 nm resolution used to measure strains in the superlattices.•Strains measured for the epitaxial layers possessing a thickness size above 4 nm.•The layers intermixing influences the layers thickness and the strains level.•Relaxation in the superlattices is due to the presence of interface dislocations. We report on quantification and elastic strain mapping in two artificial [BaZrO3]xᴧ/[BaTiO3](1-x)ᴧ (BZxᴧ/BT(1-x)ᴧ) superlattices having periods of Λ = 6.6 nm and Λ = 11 nm respectively, grown on (0 0 1) SrTiO3 single crystal substrate by pulsed laser deposition technique. The methodology consists of a combination of high-resolution scanning transmission electron microscopy and nanobeam electron diffraction associated with dedicated algorithm for diffraction patterns processing originally developed for semiconductors to record the strains at atomic scale. Both in-plane and out-of-plane elastic strains were then determined at 2 nm spatial resolution and their average values were used to map the strains along and transverse to the epitaxial growth direction of both samples to determine its variation along several BZ/BT interfaces. In addition, the variation of the width of the inter-diffusion BT/BZ interfaces and intermixing between different layers are estimated. The obtained width average value measured in these inter-diffusion interfaces vary from 8 to 12% and from 9 to 11% for both superlattices having Λ = 6.6 nm and Λ = 11 nm respectively. These inter-diffusion interfaces and the inherent elastic strains due to the confined layers of the superlattices are known to be the most important parameters, responsible of the change in their functional properties.