Initial stages of silicon-iron interface formation

The formation of a silicon-iron (Si/Fe) interface has been studied in situ by the method of high-resolution photoelectron spectroscopy using synchrotron radiation. The experiments were performed under ultrahigh vacuum conditions (at a residual pressure of 3 × 10−10 Torr) in a range of Si coating thicknesses within 0.04–0.45 nm. It is established that the process begins with the formation of a FeSi silicide and Fe-Si solid solution on the iron substrate surface. As the Si coating thickness increases, the solid solution converts into ferromagnetic (Fe3Si) and nonmagnetic (FeSi) silicides. It is shown that thermostimulated solid-state reactions leading to the transformation of FeSi and Fe3Si silicides into a semiconducting β-FeSi2 silicide start at a temperature close to 600°C.