Piezoelectrically active hydrothermal KNbO3 thin films

Abstract

In this study, a post-growth treatment has been developed for epitaxial KNbO₃ films grown hydrothermally at 200 °C so that they are ferroelectrically active. The treatment comprised of an O₂ plasma followed by thermal annealing that removed lattice hydroxyls and also reduced the concentration of oxygen vacancies. This lowered the leakage current sufficiently such that films could be poled to saturation. This has led to the first demonstration of piezoelectrically active KNbO₃ films grown hydrothermally.