Hybrid system of iron porphyrin on aminosilanized c-Si

Adsorption of iron porphyrin (FeIIITPPS4) Fe(III)meso-tetra(4-sulfonatophenyl) porphine on aminosilanized surface of crystalline Si (c-Si) was investigated. Formation of nanometric structures of FeIIITPPS4 on c-Si, the surface of which has been modified by various silanization procedures, was studied. Aqueous, ethanol and acetone solutions of 3-aminopropyltrietoxysilane (APTES) were prepared for deposition on c-Si by spinning or immersion techniques. Smooth homogeneous APTES films of thickness 100–500 nm were produced by multiple spin coating procedure. Thin APTES films of thickness ∼2.5 nm were fabricated by dipping technique followed by washing procedure. Hybrid system of FeIIITPPS4/APTES/Si was prepared from a drop of FeIIITPPS4 aqueous solution put on aminosilanized Si surface or by dipping the Si wafer in FeIIITPPS4 aqueous solution. Nanostructures of size 50–250 nm were formed along with large rings of Ø50–100 μm which have been observed at chemisorption of highly concentrated (∼1 mM) FeIIITPPS4 aqueous solution. Spectroscopic ellipsometry was used to characterize the APTES layer and to investigate the aggregation state of FeIIITPPS4. The studies provided allowed one to presume that covalent bonds were formed between amino-groups of APTES and functional groups of sulfonic acid in porphyrin leading to immobilization of FeIIITPPS4 on Si substrate.