In the mid 1980s Averin and Likharev predicted that with the use of ultrasmall tunnel junctions a time correlation of electron flow through a junction could be observed, and permit the measurement of the effect of a net charge of less than one electron on the junction. Both effects were soon experimentally verified, and since that time there has been an explosion of work in the filed of single electron devices. This chapter reviews the fundamental concepts behind the operation of such devices. it then describes some of the single electron effects studied in semiconductors. Superconducting devices are then constrasted to the semiconductor and the normal metal single electron devices. The details of some current applications are described, and a thumbnail sketch of current fabrication methods is given.
A highly functional Si nanodot array device that operates by means of single-electron effects was experimentally demonstrated. The device features many input gates, and many outputs can be attached. A nanodot array device with three input gates and two output terminals was fabricated on a silicon-on-insulator wafer using conventional Si MOS processes. Its feasibility was demonstrated by its operation as both a half adder and a full adder when the operation voltage was carefully selected.