Coulomb blockade devices fabricated by liquid metal ion source droplet deposition

The fabrication of two-dimensional multiple tunnel junction (MTJ) devices b y deposition of Au droplets from a liquid metal ion source is reported. By adjusting the emission parameters of the source and the final landing volta ge of the droplets we have been able to deposit 1 nm size islands with a go od reproducibility and with a sufficient density to allow tunneling between islands. Our devices exhibit a Coulomb gap up to a temperature of 200 K an d show nonlinear current-voltage characteristics up to room temperature. Th e thermal behavior of these devices was investigated and shows the absence of a Kosterlitz-Thouless-Berezenskii transition. The charging energy of the islands is as high as 240 meV opening interesting perspectives for the int egration of these MTJ devices in single electron memory cells working at hi gh temperature. (C) 1998 American Vacuum Society. [S0734-211X(98)09906-5].