Studies of the Structural and Electronic Properties of Self-Assembled Monolayers: Towards Molecular Electronics

Abstract

The field of Molecular Electronics (ME) is growing at a rapid pace. The study of materials that have utility at the level of several, or single, molecules is exciting becausethe development of these sorts of systems offers a pathway to potentially avoid the perils of continually shrinking Silicon-based fabrication. This work examines the state of the art in fabrication techniques for semiconductor systems, then examines current examples of ME to be found in the academic literature. This review is designed to plumb the depths of a few important demonstrations, as opposed to a broad overview of the entire body of work. Further, scanning probe lithography techniques are demonstrated that allow for the study of small ensembles of interesting molecules in isolation. By utilizing these techniques, the structural and electronic properties of molecules can be studied, with a focus towards determining the likely utility of a particular species in a ME framework. Experimental study of redox-active self-assembled monolayer (SAM) films shows that under specific conditions, some films display a negative differential resistance (NDR) response that has possible utility in the development of ME devices. Ferrocene- and galvinol-terminated SAMs both show NDR at room temperature. A possible mechanism for the NDR behavior is believed to be resonant tunneling through low-lying, accessible redox-states in the molecule.