Silica sol-gel films (SGFs) doped with various transition metals
derived by spin-coating on glass substrates and silicon wafers have been
studied. Precursor solutions were prepared by mixing tetraethylorthosilicate,
ethanol, water and nitrates of the transition metals (Cr, Mn, Fe, Co, Ni and
Cu) using HCl as a catalyst. Remarkable segregation of metals at the surface
was observed for films doped with Cu and Co. For Mn- and Ni-doped films this
effect was much less, and it vanished for the films doped with Cr or Fe. The
influence of boron and phosphorus upon the chemical state and the distribution
of metal atoms was also analysed. The structure, optical properties and
composition of the SGFs were studied and some pathways to control the dopant
segregation effect were realized.