Thickness Dependence of the Dielectric Properties of Epitaxial SrTiO3 Films on (001)Pt/SrTiO3

Abstract

Epitaxial, (001)-oriented SrTiO3 thin films were grown by sputtering on (001)Pt/SrTiO3 substrates to thicknesses ranging from 20 to 160 nm. Their dielectric properties were studied using parallel-plate capacitor structures. For film thicknesses greater than 40 nm, the thickness dependence of the capacitance density could be described with a model of low-permittivity interfacial layers that are connected in series with the bulk of the film. Thinner films showed a deviation from the linear relationship between the inverse capacitance density and thickness. They also showed an increase in loss and a small, power-law frequency dependence of the capacitance. These changes were indicative of different bulk dielectric properties of the thinnest SrTiO3 films. (C) 2008 The Japan Society of Applied Physics.