UNDERSTANDING AND MINIMIZING THE ROLE OF DEFECTS IN SELF-ASSEMBLED MONOLAYER BASED JUNCTIONS

Abstract

The interpretation of data generated by molecular electronic devices is challenging because mostly only the total current that flows across two-terminal metal-molecule-metal junctions is measured. From the total current it is difficult to distinguish the contribution of, for instance, the metal-electrode interfaces from the molecular component. All components of the junctions are equally important and the fabrication of each has to be optimized to ensure good control over the supramolecular structures of the junction. Practical devices always contain defects but mostly it is now known what kinds of defects are present in the junctions and how they affect the electrical characteristics. This thesis addresses these issues and describes new methods to minimize defects in junctions by optimizing the fabrication of the bottom-electrodes, top-electrodes, and molecular monolayers, and introduces new methods to identify defects in junctions. Finally, the thesis gives examples of how these improvements can be used in subtle physical-organic studies of charge transport and to optimize the performance of molecular diodes.