Effects of individual layer thickness on the structure and electrical properties of sol-gel-derived Ba_0.8Sr_0.2TiO₃ thin films

Ba_0.8Sr_0.2TiO₃ thin films were prepared with various individual layer thicknesses using a sol-gel process. The individual layer thickness strongly affected the structure, ferroelectricity, and dielectric properties of the films. The films prepared with an individual layer thickness of 60 nm showed small equiaxed grains, cubic structure, temperature-independent dielectric constant, and no ferroelectricity. The films prepared with an individual layer thickness of 8 nm showed columnar grains, tetragonal structure, good ferroelectricity, and two dielectric peaks in the dielectric constant-temperature curve. The individual layer thickness for layer-by-layer homoepitaxy growth that resulted in columnar grains was <20 nm.