Epitaxial Growth and Dielectric Properties of (Ba 0.24 Sr 0.76 )TiO 3 Thin Film

A (Ba 0.24 Sr 0.76 )TiO 3 thin film was epitaxially grown on a Pt/MgO(100) substrate by rf magnetron sputtering, and its dielectric properties were evaluated. The thin film had a dielectric constant of 1400 at zero bias field. A drastic decrease of dielectric constant was observed when bias field was applied. Based on the experimental results on the epitaxial film, size effects reported in the dielectric constant of (Ba x Sr 1- x )TiO 3 polycrystalline thin films were discussed. Both the sensitive bias field dependence of the dielectric constant and the existence of strong local fields are probably the origin of the size effects observed in (Ba x Sr 1- x )TiO 3 thin films.