X-ray reflectivity study of the structural characteristics of BaTiO3/LaNiO3 superlattice

摘要

[[abstract]]An artificial superlattice of BaTiO3/LaNiO3 (BTO/LNO) was grown epitaxially on an Nb-doped SrTiO3 (001) single-crystalline substrate with a dual-gun rf magnetron sputtering system. The structural characteristics of the superlattice films were studied mainly by X-ray reflectivity. Formation of a superlattice structure was confirmed from the appearance of Bragg peaks separated by Kiessig fringes in X-ray reflectivity curves and a crystal truncation rod (CTR) spectrum. The surface and interfacial roughness of the superlattice were derived from the fitted curves for specular reflectivity. A conformal relationship between consecutive BTO and LNO layers was observed from off-specular scattering. According to the fitted results and atomic-force microscopy images, the evolution of surface structure follows the Stranski–Krastanov (S–K) growth mode, in which the surface roughness increased with the thickening of sublayers.