Studies of composite system of iron porphyrin immobilized on aminosilanized Si

Composite system of iron porphyrin (FeTPPS) on aminosilanized Si substrates was investigated by studies of surface morphology and optical response. Aminofunctionalized siloxane films on silicon substrates were produced from different sol-gel precursors prepared from 3-aminopropyltriethoxysilane (APTES) dissolved in water, ethanol and acetone. Immersion technique was used for the formation of APTES films. Aqueous solutions of FeTPPS were deposited on aminosilanized Si substrates. Topographic features of nanostructures in composite FeTPPS/APTES/Si system were investigated by atomic force microscopy (AFM) technique. High-resolution phase contrast imaging revealed the substructure of siloxane films on silicon substrates and nanoaggregates of FeTPPS immobilized on aminosilanized Si surface. Spectroscopic ellipsometry measurements were carried out in the region 1-5 eV in order to characterize the siloxane films and composite structures. The analysis of obtained results allowed one to conclude that FeTPPS molecules were attached to the surface by covalent bonds between the functional group of sulfonic acid SO3- of iron porphyrin and (-NH2H+)-group of APTES.