Structural Transition in Cu/Fe Multilayered Thin Films

Abstract

Microstructural development of Fe and Cu in Cu/Fe multilayers of layer thickness 1.5–10 nm prepared on Si, Ge, and MgO substrates by ion beam sputtering has been studied using x-ray diffraction and cross-sectional transmission electron microscopy (TEM). High-angle x-ray results show an fcc Cu structure and a distorted bcc structure in the Fe layers at 5 nm-layer-thickness and smaller, and bcc Fe (110) and fcc Cu (111) peaks in the 10 nm-layer-thickness samples. Lowangle x-ray diffraction indicates that the layers in the samples grown on MgO substrates have a more uniform and smooth layered structure than the multilayers grown on Si and Ge substrates, which results from larger grains in the MgO substrate samples for the same layer thickness. Relationships among growth, microstructure, and interfaces with layer thickness are discussed.