Thickness Dependence of Electrical Properties for High-k SrTa₂O₆ Thin Films Fabricated by Sol–Gel Method

Abstract

The interface between SrTa 2 O 6 thin films and Pt electrodes, and defects in SrTa 2 O 6 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/cm 2 were obtained for the 150 nm SrTa 2 O 6 thin film. These values are comparable with metal organic chemical vapor deposition (MOCVD) derived SrTa 2 O 6 thin films. Space-charge limited current mechanism predominated in the 113 and 150 nm SrTa 2 O 6 thin films. Higher Ti concentration was found in the layer close to the bottom interface of 113 and 150 nm SrTa 2 O 6 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 SrTa 2 O 6 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.