Tunneling through a single quench-condensed cluster

Quench-condensed bismuth films of 3-5 nm thickness have been used as a clus ter source to prepare Single Electron Transistors (SET) based on a single c luster with high charging energy. We used electron-beam defined shadow evap oration masks to pattern la nm wide constrictions in these films. By increm ental depositions through these masks controlled by in situ sample conducta nce measurements, we obtained a SET geometry for clusters with, charging en ergies up to 90 meV Our experiment showed that the SET geometry can be achi eved 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 alw ays higher than 10 meV.