Structural characterization of sputter-deposited Ba0.48Sr0.52TiO3/LaNiO3 artificial superlattice structure by X-ray reflectivity and diffraction

Ba0.48Sr0.52TiO3/LaNiO3 artificial superlattices with a symmetric sublayer structure were successfully fabricated on Nb-doped SrTiO3 (001) single-crystalline substrate with rf magnetron sputtering. 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 a diffraction pattern. The fitted result from X-ray reflectivity curves shows that the densities of the Ba0.48Sr0.52TiO3 and LaNiO3 sublayers were slightly less than their bulk values. The appearance of discernible satellite peaks beside the main peak of the crystal truncation rod observed for deposited films clearly demonstrates that a well-defined superlattice structure can be formed with rf sputtering. The artificial Ba0.48Sr0.52TiO3/LaNiO3 superlattices exhibit a large dielectric constant and a small dielectric loss. The smaller is the stacking periodicity of superlattices, the larger is the dielectric constant and dielectric loss.