Single and many-electron phenomena in semiconductor and metal nanostructures studied by scanning tunneling microscopy

This dissertation deals with experimental studies of single and many-electron phenomena observed in semiconductor and metal nanostructures.; We have observed correlated single electron tunneling in a system consisting of an oxidized silicon tip and graphite sample. Our results reveal quantization in the tunneling current. It is observed as steps in the current-voltage characteristic and is explained by Coulomb blockade of single electrons trapped in the oxide layer.; Photon emission induced by electronic excitation of the surface plasmons on a granular gold surface was also investigated. Nano-granular thin films were produced by vapor deposition of gold on mica. Scanning tunneling microscopy showed that small particles had formed after deposition with an average size of about 25 nm. We measured the intensity of light emission as a function of the applied bias voltage and observed resonance peaks at 1.9 V and 2.7 V. Elastic electron tunneling mechanism allows the assignment of these peaks to the local and the extended plasmons of the granular gold surface.; We have observed nanogranular gold surfaces with particles arranged in various ways. Arrangements in a close packed lattice and in a "herringbone" pattern are shown. Such configurations indicate particle-particle interactions that mirror atomic interactions in producing both the lattice and its surface reconstruction. Analogous to the case of atoms, these interactions are also believed to be mediated via electrons. By annealing, we have observed the transformation of a surface consisting of nearly spherical particles into nanosized crystals with flat top facets and hexagonal shapes.