Thickness Dependence of Electrical Properties for High-kSrTa₂O₆Thin Films Fabricated by Sol–Gel Method

Abstract

The interface between SrTa2O6 thin films and Pt electrodes, and defects in SrTa2O6 thin films were investigated through the study of thickness dependence. High dielectric constant of about 109 and low leakage current density of about 10-8 A/cm2 were obtained for the 150 nm SrTa2O6 thin film. These values are comparable with metal organic chemical vapor deposition (MOCVD) derived SrTa2O6 thin films. Space-charge limited current mechanism predominated in the 113 and 150 nm SrTa2O6 thin films. Higher Ti concentration was found in the layer close to the bottom interface of 113 and 150 nm SrTa2O6 thin films. From these results, we suggest a two-layered model for these two thin films. The anomalous dispersion of loss tangent and Poole–Frenkel predominated leakage current was found in 75 nm SrTa2O6 thin film. This may be induced by higher Ti concentration not only in the layer close to the bottom interface, but also in the whole thin film.