LAUSR

Optical reflection spectra in the photon energy range of 1.5-6 eV have been studied after the growth of ultrathin iron films on silicon (001) in the 0-1.2 nm thickness range. It has been noted that the reflection coefficient values vary nonmonotonically in thickness near the limiting energy of 1.5 eV and 6 eV. Moreover, they are abnormally large one at 1.5 eV and small one at 6 eV. It is shown that these phenomena can not be explained by simple models of the formation of a metallic, silicide film or amorphous silicon layer at the interface and correspond to structural-phase transformations in the film and in the substrate interface region.