5 - Self-Assembled Monolayer Covalently Fixed on Oxide-Free Silicon

Abstract

Self-assembling, in which minute elements such as atoms, molecules, and clusters are spontaneously organized into an ordered array of the elements, is a key process of the bottom-up nanotechnology. One of the promising material processes on the basis of self-assembly is the fabrication of organic thin films with a monomolecular thickness, that is, self-assembled monolayer (SAM). Such SAMs formed on silicon (Si) substrates which bear no surface oxide layer are reviewed in this chapter. First, a brief introduction to the history of such direct-bonded SAMs on Si and chemical reactions of organic molecules on hydrogen-terminated Si (Si-H) for the formation of direct-bonded SAM is described. In particular, photochemical reactions of 1-alkenes with Si-H under a mild excitation condition with visible light and the reaction mechanism are discussed. Next, chemical and mechanical durabilities of direct-bonded alkyl and alcohoxy SAMs on Si are demonstrated. Furthermore, the properties of a hexadecyl SAM on Si as an insulator are also introduced. Finally, the immobilization of ferrocene derivatives on Si in order to fabricate electro-active Si is demonstrated.