Control of Coulomb blockade characteristics with dot size and density in planar metallic multiple tunnel junctions

Coulomb gap width has been controlled in a planar metallic structure made by focused ion-beam deposition with landing energies in the range 10 eV-1 keV. Gold islands form by surface diffusion, with size and density determined by dose and landing energy. Increasing the dose reduces the Coulomb gap systematically as larger islands form and density is reduced. Lower ion landing energy increases the operating temperature despite an apparent increase in island size. Multiple tunnel junctions of lengths 10-200 nm have been fabricated and Coulomb blockade observed up to 200 K, with strong nonlinearities evident at room temperature. Single-electron transport through a single island has also been observed, exhibiting a periodic Coulomb staircase. (C) 1999 American Institute of Physics. [S0003-6951(99)02129-4].