Comparative scanning-tunnelling-microscopy investigations of nanostructures prepared by different techniques

Conducting nanoscale structures (dots, particles and wires) are fabricated by means of four different techniques on chemically cleaned, H-terminated Si substrates and investigated using a scanning tunnelling microscope (STM) operated under high-vacuum conditions. We distinguish between STM tip-independent or ‘global’ techniques (formation of colloids by wet chemical methods; condensation of particles from the vapour phase in a low-pressure background noble gas) and tip-assisted or ‘local’ techniques (field-induced transfer of tip material; electron-stimulated decomposition of organometallic compounds). These fabrication techniques are compared and evaluated, e.g., with respect to the particle stability on the substrate surface at room temperature and the capability of manipulating individual particles, in order to address the issue of designing prototype hybrid structures by the controlled assembling of nanoparticles and electrically connecting these structures to the ‘outside world’ by means of an STM.