Narrow Results

Influence of substrate-temperature on the interfacial structure of Fe₃Si/FeSi₂ layered films deposited on a Si(111) substrate were studied. Fe₃Si/FeSi₂ films with sharp interfaces were grown at room substrate-temperature. At a substrate-temperature of 300 °C, interfaces between the Fe₃Si and FeSi₂ layers were obviously unsharpened, while the crystallinity of Fe₃Si was enhanced. The compositional periodic structure was barely unsharpened and it was nearly the same as that of the films deposited at room substrate-temperature. Epitaxial growth of Fe₃Si layers across FeSi₂ layers was carried out. This substrate-temperature is the upper limit at which the heterostructure formation takes place. At 400 °C, ε-FeSi was formed due to activated interdiffusion, and the structure of Fe₃Si changed partially from B2-type to DO₃-type.

Three-dimensional atomic arrangements of ultra thin Fe silicide films were directly revealed. By using circularly polarized light with opposite helicities, forward focusing peaks with their positions shifted in photoelectron angular distribution (PEAD) patterns can be obtained. We successfully observed the PEAD patterns of ultra thin Fe silicide films from different core levels of Fe and Si atoms by display-type spherical mirror analyzer (DIANA). The element selective stereo photographs indicate similar hexagonal atomic arrangement with three-fold symmetry for Si and Fe atoms, which is consistent with a model based on a CsCl-type structure with B-type stacking. This is the first observation of stereoscopic atomic arrangements for ultra thin compound films, which implies that the stereo atomscope is very powerful structure analysis tool also for complex structures on surface.