title: Molecular layer deposition of thiol-ene multilayers on semiconductor surfaces.
abstract: The fabrication of organic thin films with controlled chemical structure in the vertical direction (parallel to surface normal) is important for many practical and technological applications in organic electronics, chemical-resistant films, and biocompatible materials, among others. In order to achieve composition control in the z-direction, molecular layer deposition (MLD: covalent layer-by-layer assembly) of thin, organic films on silicon, silicon oxide, and germanium surfaces was carried out, using the well-established UV-induced thiol-ene reaction. Through successive contact of an interface with dithiol and diene molecules under UV irradiation for short periods (approximately 30 min, room temperature), well-defined thin films can be obtained. Linear increases in film thickness with respect to layer number were obtained for shorter aliphatic dienes and dithiols (C < or = 8), but with longer molecules and with aromatic substrates a self-limiting situation sets in whereby both ends of the molecule react with the surface, arresting film growth. The functionalized interfaces were characterized by ellipsometry, X-ray photoelectronic spectroscopy, and atomic force microscopy.
authors.affiliation: Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada.
authors.forename: Yun-hui
authors.initials: YH
authors.lastname: Li
authors.forename: Dong
authors.initials: D
authors.lastname: Wang
authors.forename: Jillian M
authors.initials: JM
authors.lastname: Buriak