Structure of Fe3Si/Al/Fe3Si thin film stacks on GaAs(001)

Fe3Si/Al/Fe3Si/GaAs(001) structures were deposited by molecular-beam epitaxy and characterized by transmission and scanning electron microscopy, and x-ray diffraction. The first Fe3Si film on GaAs(001) grew epitaxially as a (001) oriented single crystal. The subsequent Al film grew almost {111} oriented in a fibrous texture although the underlying Fe3Si is exactly (001) oriented. The growth in this orientation is triggered by a thin transition region which is formed at the Fe3Si/Al interface. In the end, after the growth of the second Fe3Si layer on top of the Al, the final properties of the whole stack depended on the substrate temperature T-s during deposition of the last film. The upper Fe3Si films are mainly {110} oriented although they are poly-crystalline. At lower T-s, around room temperature, all the films retain their original structural properties.