FWF - Molekulare UE d Si K - Molecular substructures of the silicon crystal lattice

The development of microelectronics toward higher integration density is to encounter some fundamental physical limits in the near future. As a consequence research efforts have been made to develop molecular electronics (in contrast to nowadays solid state electronics). One aspect of these studies deals with the investigation of small sub-structures of the silicon lattice, as for instance the generation of silicon nano-crystals. While such materials are mainly synthesized employing physical techniques (for example vapor deposition, epitaxial growth and others) the research outlined in the current proposal is pursuing an approach to molecular precursor materials which are subjected to rearrangement conditions. The advantages of this entry are its high selectivity, simple characterization of the materials and especially the flexibility. In some preliminary work to the project it has been shown that the first example of an all sila-adamantane, which is the smallest substructure of the silicon lattice (and actually also the smallest possible silicon nano crystal) could be synthesized. The obtained molecule is a tricyclic, unstrained compound which can be subjected to further derivatisation reactions. Taking this as a starting point, the chemistry and physical properties of the sila-adamantanes will be studied. These compounds can be considered to be the "missing link" between bulk silicon and the class of polymeric organosilicon compounds (polysilanes). This state demands for a thorough examination of physical (spectroscopic) and chemical properties and comparison with solid state bulk silicon. Also the functionalization of the sila-adamantanes, as well as the synthesis of higher substructures of the silicon lattice will be investigated. By the introduction of atoms others than silicon (especially phosphorus and boron) into the scaffold of the adamanatanes the physical process of doping shall be studied at a molecular level.