Morphological and compositional study at the Si/Fe interface of (Fe/Si) multilayer

Diffusion and reaction of elements at the interfaces of nanostructured systems play an important role in controlling their physical and chemical properties for subsequent applications. (Fe/Si) nanolayers were prepared by thermal evaporation under ultrahigh vacuum onto a Si(100) substrate. A morphological characterization of these films was performed by combination of scanning transmission electron microscopy (STEM) and X-ray reflectivity (XRR). The compositional depth profile of the (Fe/Si) structures was obtained by angle resolved X-ray photoelectron spectroscopy (ARXPS) and hard X-ray photoelectron spectroscopy (HAXPES). Moreover, determination of the stable phases formed at the Si on Fe interfaces was performed using conversion electron Mössbauer spectroscopy. The Si/Fe interface thickness and roughness were determined to be 1.4 nm and 0.6 nm, respectively. A large fraction of the interface is composed of c-Fe1-xSi paramagnetic phase, though a minoritary ferromagnetic Fe rich silicide phase is also present.
The financial support of the Spanish MINECO MAT2011-23791, the President of Russia Grant (NSh-1044.2012.2), RFFI grant 13-02-01265, the Ministry of Education and Science of Russian Federation, projects GK14.B37.21.1276 and GK16.740.11.0740, Aragonese DGA-IMANA E34 (cofunded by Fondo Social Europeo) and that received from the European Union FEDER funds are acknowledged. L. B. R. acknowledges the Spanish MINECO FPU 2010 grant.