Optical properties of Fe-doped silica films on Si

Optical properties of Fe-doped silica films on Siwere investigated by ellipsometric technique in the region 1–5 eV. Samples were produced by sol– gel method. Precursors were prepared bymixing tetraethoxysilane (TEOS) solution in ethanol and water with aqueous solution of Fe-chloride or Feacetate. The coating solution was deposited on Si substrates by spin on technique. The size of Fe-containing nanometric-sized particles depended on technology and varied from 20 to 100 nm. Optical response of complex hybrid samples SiO2:Fe/Si was interpreted in a multi-layer model. In the inverse problem, the Maxwell equations were solved by transfer matrix technique. Dielectric function of Fe-doped silica layers was calculated in the model of effective media. Analysis of optical data has shown that various Fe-oxides formed. Experimental data for films obtained fromprecursors with Fe-acetate and annealed in hydrogen were well described by the model calculations taking into account a small contribution 1–5% of metal Fe imbedded in silica. The Fe/Fe–O contribution to optical response increased for samples grown from FeCl3-precursor. Ellipsometric data for Fe-doped silica films on Si were interpreted taking into account the structural AFM studies as well as the results of magnetic measurements