Epitaxy of Pd thin films on (100) SrTiO3: A three-step growth process

Abstract

Control of the orientation of thin Pd films on (100) SrTiO3 surfaces was obtained by changing the growth temperature. In particular, a three-step growth method was applied to deposit thin single-crystal Pd films on single-crystal (100) SrTiO3 surfaces. This was realized by first growing epitaxial Pd seeds at elevated temperatures. Subsequently, the seeds were overgrown at room temperature by polycrystalline Pd which fully covered the substrate at a low thickness. Annealing of these films promoted growth of the epitaxial seeds, resulting in single-crystal Pd films: (100) SrTiO3∥(100) Pd, [010] SrTiO3∥[010] Pd. The three-step growth method turned out to be a useful method to overcome surface roughening and the creation of crystalline imperfections in thin Pd films. This is essential for the growth of thin metallic epitaxial buffer layers. The microstructure of the films was analyzed by reflection high-energy electron diffraction, scanning electron microscopy, x-ray diffraction, and transmission electron microscopy.