Double-island single-electron devices. A useful unit device for single-electron logic LSI's

We fabricated a single-electron device that is useful as a unit device for single-electron logic circuits. The device is a three-current-terminal device fabricated on a silicon-on-insulator (SOI) wafer, which includes two Si islands whose electric potential can be controlled by gates. Sub-50-nm Si islands were integrated in an area smaller than 0.02 /spl mu/m/sup 2/ through self-aligned formation of the islands by pattern-dependent oxidation (PADOX) of a T-shaped wire. By PADOX, each island was embedded in one branch of the T-shaped wire. We show two electrical characteristics which demonstrate the usefulness of this device as a circuit element. First, current switching between two branches was performed at 30 K by using gate voltage to control the Coulomb blockade in each island. Second, a correlation between the two currents was observed because the two islands were integrated close to each other. The latter indicates a capacitive coupling between the islands, which opens up the possibility of one-by-one transfer of electrons in this device. These findings show that the proposed island-integration technique is applicable to making ultra-low-power and highly integrated single-electron circuits.