Keywords: organic molecules, silicon surfaces, adsorption, STM, HREELS, molecular electronics, surface photovoltage, monolayers, nanotechnology, molecular sensors, microelectronics, alkenes, alkynes, aldehydes, chain reaction, molecular nanostructures
Organics on silicon; single molecules, nanostructures and monolayers
Controlled attachment of organic molecules to silicon surfaces offers the promise of enabling a new class of molecular electronic devices and sensors with the potential to significantly enhance the functionality of conventional microelectronics. In this review, we describe recent progress in probing and understanding the interaction of organic molecules with clean and H-terminated silicon surfaces. While unsaturated molecules react readily with the dangling bonds on the clean surface, typically adopting multiple bonding configurations, hydrogen terminated surfaces with a small number of isolated reactive sites can be used to increase the selectivity of these reactions. At single dangling bonds a variety of molecules (alkenes, alkynes and aldehydes) react with the surface via a propagating chain reaction, resulting in the formation of molecular nanostructures. Such propagating chain reactions can also be exploited to form molecular monolayers with a range of terminal functionalities. The properties of these monolayers appear promising for device and sensor applications.