Hybrid system of iron porphyrin on aminosilanized c-Si

Abstract Adsorption of iron porphyrin (Fe III TPPS 4 ) Fe(III) meso -tetra(4-sulfonatophenyl) porphine on aminosilanized surface of crystalline Si (c-Si) was investigated. Formation of nanometric structures of Fe III TPPS 4 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 Fe III TPPS 4 /APTES/Si was prepared from a drop of Fe III TPPS 4 aqueous solution put on aminosilanized Si surface or by dipping the Si wafer in Fe III TPPS 4 aqueous solution. Nanostructures of size 50–250 nm were formed along with large rings of O50–100 μm which have been observed at chemisorption of highly concentrated (∼1 mM) Fe III TPPS 4 aqueous solution. Spectroscopic ellipsometry was used to characterize the APTES layer and to investigate the aggregation state of Fe III TPPS 4 . 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 Fe III TPPS 4 on Si substrate.