Fabrication of lateral tunnel junctions and measurement of Coulomb blockade effects

In order to operate single-electron devices at high temperatures, a fabrication process for laterally arranged double tunnel junctions is presented. The dimensions of the island can be reduced relatively easily down to the resolution limit of lithography, resulting in extremely low capacitances. The basic idea of the fabrication process is a very thin metallic nanowire which is made discontinuous by means of a sharp-edged groove in the substrate. Tunnel junctions are formed at either edge of the groove, and the tunnel barrier gap can be adjusted via the depth of the groove and the deposition parameters of the metal film. Coulomb blockade was observable, which is persistent up to temperatures above 77 K.