Stable and metastable iron silicide phases on Si(1 0 0)

The formation of iron silicide and the reaction in interface between Fe and Si(1 0 0) were investigated by conversion electron Mössbauer spectroscopy. Depending on the thickness of the iron film (3–20 ML), different phases were observed. The reaction rate between Fe and Si was also thickness dependent. Depending on the Fe thickness and on the annealing temperature, stable (ε-FeSi, β-FeSi2) and metastable (disordered, c-FeSi) phases were formed. At 3 ML iron thickness an amorphous phase with hyperfine interaction parameters characteristic to that of amorphous iron silicide phase with 50 at.% Si content appeared. The parameter values of this phase changed significantly around 673 K indicating the transformation of the structure close to that of ε-FeSi. At 8 and 20 ML Fe thicknesses magnetic split spectra with distribution were detected. After annealing, metastable c-FeSi, stable ε-FeSi and at higher temperature stable β-FeSi2 phases were formed.