Strain-Mediated Substrate Effect on the Dielectric and Ferroelectric Response of Potassium Sodium Niobate Thin Films
authors Tkach, A; Santos, A; Zlotnik, S; Serrazina, R; Okhay, O; Bdikin, I; Costa, ME; Vilarinho, PM
nationality International
journal COATINGS
author keywords KNN thin films; sol-gel; thermal expansion; stress/strain; ferroelectric hysteresis; dielectric properties
abstract If piezoelectric thin films sensors based on K0.5Na0.5NbO3 (KNN) are to achieve commercialization, it is critical to optimize the film performance using low-cost scalable processing and substrates. Here, sol-gel derived KNN thin films are deposited using a solution with 5% of potassium excess on Pt/TiO2/SiO2/Si and Pt/SrTiO3 substrates, and rapid thermal annealed at 750 degrees C for 5 min. Despite an identical film morphology and thickness of similar to 335 nm, an in-plane stress/strain state is found to be tensile for KNN films on Pt/TiO2/SiO2/Si, and compressive for those on Pt/SrTiO3 substrates, being related to thermal expansion mismatch between the substrate and the film. Correspondingly, KNN films under in-plane compressive stress possess superior dielectric permittivity and polarization in the parallel-plate-capacitor geometry.
publisher MDPI
issn 2079-6412
year published 2018
volume 8
issue 12
digital object identifier (doi) 10.3390/coatings8120449
web of science category Materials Science, Coatings & Films
subject category Materials Science
unique article identifier WOS:000455200300035