Electrical Properties of Mg Doped (Ba0.5Sr0.5)TiO3 Thin Films

The microstructures and electrical characteristics of Mg doped (Ba0.5Sr0.5)TiO3 (BSTM) thin films were investigated as a function of Mg content. Also the multi-layered structure, BSTM/BST/BSTM was proposed to improve both of the leakage current and dielectric constant. With increasing Mg content, the perovskite peak intensity slightly decreased and grains became smaller. For the films above 15 mol% Mg, the secondary phase (MgTi2O5) was observed in X-ray diffraction (XRD) patterns. The dielectric constant decreased with increasing Mg content, while leakage current decreased up to 10 mol% Mg and then increased with further addition, which were explained by the effect of grain size and charge compensation. For the BSTM/BST/BSTM multi-layered films, the leakage current dramatically decreased without reduction of the dielectric constant when the thicknesses of BSTM and BST were 70 nm and 210 nm, respectively. These results confirm that a promising BST thin film capacitor can be obtained by introduction of Mg modified multi-layer structure.