Figure 1. Summary of current accomplishments and future studies of nanostructures on graphite surface.

It is quite astonishing that we know more about complex individual molecules bound to well-defined substrates than we do about larger, 5-200 nm structures, where the measurements themselves are more straightforward but the interpretation of the results is more complex compared to single molecule studies. The main goal of this project is to measure, control, and tune the properties of specifically designed semiconductor nanostructures. This project is based on the concept of molecule corrals that can be produced on a surface of highly oriented pyrolytic graphite by inducing defects of specific depth and in a specific pattern followed by oxidation in air (Collaboration with Professor T. P. Beebe, Jr., Department of Chemistry and Biochemistry, University of Delaware). The pits can be prepared with high precision and narrow size distribution in lateral dimensions between about 5 and 200 nanometers. These nanostructures can be further filled with a desired material, presenting a completely novel field of study. Specifically, as summarized in Figure 1, we can now prepare sets of pits of narrow size distribution and deposit silicon (and other materials) by evaporation to produce surface nanostructures in a shape of either silicon “donuts” (with empty centers) or silicon “mesas”. The “donuts” can be further decorated with gold to be used for chemical oxidation studies. The surface of the “mesas” can be modified with the chemistry previously developed in our group for silicon single crystals. This unique model will be further used for studies in the areas of microelectronics (high-density transistors), molecular conductance, and sensing, that are currently underway. In the future, this project will use the advances of the diffusion barrier film deposition to be applied to the nanostructured materials. Another direction will integrate this project with our current work on covalent attachment of biological molecules to self-assembled monolayers on silicon for potential applications in biosensing, as outlined in the next part.