Tunneling through a single quench-condensed cluster

Quench-condensed bismuth films of 3-5 nm thickness have been used as a cluster source to prepare Single Electron Transistors (SET) based on a single cluster with high charging energy. We used electron-beam defined shadow evaporation masks to pattern la nm wide constrictions in these films. By incremental depositions through these masks controlled by in situ sample conductance measurements, we obtained a SET geometry for clusters with, charging energies up to 90 meV Our experiment showed that the SET geometry can be achieved in every sample preparation ran, despite the apparent random nature of cluster formation in granular films. The resulting charging energy of the transistor varied from experiment to experiment. As value, however, was always higher than 10 meV.