| The importance of molecular nanotechnology has recently been underscored by increased media, public, and government awareness of the subject. This thesis examines several nanotechnology issues on the technologically significant Si(100) surface with the ultra-high vacuum scanning tunneling microscope (UHV-STM). Nanoscale studies have revealed that the in situ H-passivated Si(100) surface remains atomically pristine even after exposure to ambient conditions. The robustness of this surface suggests its use as a chemically inert resist layer. Using feedback-controlled lithography (FCL), individual hydrogen atoms can be removed from the Si(100)-2x1:H surface. The remaining dangling bond patterns serve as atomically precise templates upon which other materials can spontaneously self-assemble. By utilizing this selective chemistry in situ, several organic molecules (e.g., norbornadiene (NBE), copper phthalocyanine (CuPc), and C60) have been isolated. The mechanical, chemical, and electronic properties of these individual adsorbed species are then immediately detected with the STM. For CuPc, the spatial extent of charge transfer from the substrate to the adsorbate is measured as a function of binding orientation. When the CuPc is reduced with ammonia, single molecule rotation is observed. STM spectroscopic measurements on C 60 reveal intramolecular variations in the electronic density of states. For electronic applications, the application of lateral electrical fields to individual molecules is crucial. A fully compatible electrical contacting scheme based on p-n junctions will be presented. Efficient STM potentiometric location of these p-n junctions suggests their additional use as alignment markers. Beyond outlining advances in molecular nanoelectronics, this thesis will also draw connections between fundamental silicon research and current technology. |
