1,2-Epoxyalkane: Another Precursor for Fabricating Alkoxy Self-Assembled Monolayers on Hydrogen-Terminated Si(111).

This work describes the UV alkoxylation of a series of 1,2-epoxyalkanes on the hydrogen-terminated silicon (H-Si) substrate. The formation of alkoxy self-assembled monolayers (SAMs) and the nature of bonding at the surface of H-Si were examined using water contact angle goniometer, spectroscopic ellipsometer, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy. UV exposure to 1,2-epoxyalkane mesitylene solution for 60 min formed alkoxy-SAMs onto H-Si with hydrophobic properties. The local molecular environment of the alkyl chains transitioned from a disordered, liquid-like state to an ordered, crystalline-like structure with increasing the chain length. XPS and FTIR indicated that the reaction of H-Si with 1,2-epoxyalkane produced Si-O-C linkages. The Si-H bond homolysis and electron/hole were the plausible mechanistic routes for the grafting of 1,2-epoxyalkanes.