Ellipsometric comparison of the native oxides of silicon and semiconducting iron disilicide (β-FeSi2)

The optical properties of the native oxide of semiconducting iron disilicide (β-FeSi2) were examined by spectroscopic ellipsometry and reflectance measurements. The room temperature oxide grown directly after removal from the preparation chamber, as well as after etching in NH4F solution, was investigated. In all cases the spectral influence in the optical spectra can be modelled by SiO2. The oxidation kinetics of β-FeSi2 were found to be very similar to those of silicon. There were no signs of iron oxides or segregation of Fe or Si. The results suggest that the native oxide of β-FeSi2 is SiOx (x≤2).