Characteristics of sputter-deposited BaTiO3/SrTiO3 artificial superlattice films on an LaNiO3-coated SrTiO3 substrate

Artificial superlattices consisting of BaTiO3 (BTO) and SrTiO3 (STO) sublayers were epitaxially grown on an LaNiO3-coated SrTiO3 (0 0 1) single-crystal substrate by a triple-gun radio-frequency (RF) magnetron sputtering system. X-ray reflectivity and high-resolution diffraction measurements were employed to characterize the microstructure of these films. Formation of a superlattice structure was confirmed from the appearance of Bragg peaks separated by Kiessig fringes in X-ray reflectivity curves and the (0 0 l) Bragg reflection of X-ray. The clearly discernible main feature and satellite features on both sides of the substrate about the (0 0 2) STO Bragg peak indicate the high quality of the BTO/STO artificial superlattice structure formed on a LaNiO3-coated SrTiO3 substrate. These BTO/STO artificial superlattices show a significant enhancement of dielectric constant relative to BTO and STO single layers of the same thickness. The higher the deposition temperature, the larger the dielectric constant of the films present; the smaller the stacking periodicity of superlattices, the larger the dielectric constant and dielectric loss.