Characterization of the dielectric properties of covalently attached organic films on silicon surfaces

Monolayers of methyl-undecanoate were constructed on silicon surfaces via a covalent Si-C bond. The molecular monolayers were characterized by high resolution electrical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and ellipsometry and displayed a densely packed monolayer. After formation of the monolayer, the methyl ester was hydrolyzed without noticeable change in the integrity of the monolayer. The carboxyl terminated organic layer was then reacted with (1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide to form active N-hydroxy succinimide ester groups. The activation chemistry was confirmed by XPS and the substructure of the methyl-undecanoate carboxylic acid and the N-hydroxy succinimide ester terminated films were characterized using EIS. XPS and EIS spectra provided information on the chemical composition and substructure of the monolayers for each step in the chemical modification of the surface.