Regensburg 2022 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 20: Poster
DS 20.1: Poster
Mittwoch, 7. September 2022, 16:00–18:00, P3
Thickness effect on ferroelectric domain formation in compressively strained K0.65Na0.35NbO3 epitaxial films — •Yankun Wang1,2, Saud Bin Anooz1, Gang Niu2, Martin Schmidbauer1, Lingyan Wang2, Wei Ren2, and Jutta Schwarzkopf1 — 1Leibniz-Institut für Kristallzüchtung, Max-Born-Str. 2, 12489 Berlin, Germany — 2Electronic Materials Research Laboratory, Xi'an Jiaotong University, Xi'an, China
Ferroelectrics are of increasing interest for a broad range of applications such as nonvolatile memory devices, transducers and MEMS sensors. Herein, the influence of thickness in epitaxial K0.65Na0.35NbO3 ferroelectric thin films grown on (110) TbScO3 substrate is systematically studied. By combining piezoresponse force microscopy and high-resolution x-ray diffraction, the occurrence of 90° stripe domains was demonstrated for the films with a thickness above 11 nm, while the domain periodicity is in good agreement with Kittel*s law. Furthermore, up to a thickness of 93 nm, elastic strain relaxation induced by the formation of ferroelectric domains is observed, whereas plastic strain relaxation plays only a minor role. With increasing film thickness three successive phases of ferroelectric domains were observed: i) Irregularly arranged orthorhombic c domains in the thinnest film, ii) periodically arranged 90° monoclinic MC domains up to a thickness of 25 nm and iii) flux closure vortex-like structure in thicker films to achieve the lowest equilibrium energy. These results demonstrate the importance of understanding the lattice relaxation mechanisms for intentional tuning of ferroelectric thin film properties.