Microwave dielectric properties of BaTiO3 and Ba0.5 Sr0.5 TiO3 thin films on (001) MgO

Abstract

The microwave properties of BaTiO3 and Ba0.5 Sr 0.5 TiO3 films were characterized as a function of in-plane film strain, crystallographic direction, film distortion, and dc bias. The strain dependence of BaTiO3 and Ba0.5 Sr0.5 TiO3 films showed an opposite pattern at room temperature, going from compression to tension, or vice versa. At zero bias, the dielectric constant and dielectric loss showed little dependence on direction ([100] and [110]). However, the tunability was consistently smaller along the [110] direction than along [100]. These observations agreed well with our previous work on how polarizations (both ionic and spontaneous) form and contribute to the nonlinear dielectric behavior. © 2009 U.S. Government.