Single-electron transistors: Electrostatic analogs of the DC SQUIDS

Abstract

Dynamics of two simple structures (Fig. 2) comprising twin pairs of small tunnel junctions is analyzed. If the single-electron conductances <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R\min{1.2}\max{-1}</tex> and capacitances C <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1.2</inf> of the junctions are small enough (Eq 1), the dynamics is influenced drastically by e-quantization of the electrical charge Q of the central electrode. As a result, the structures become close analogs of the dc SQUIDs within the framework of the well-known electro <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\leftrightarrow</tex> magnetic duality ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q\leftrightarrow\Phi</tex> , etc.). In particular, the dc I-V curves of the structures can be controlled by the "gate" voltage U, so that the devices can be used as "Single-Electron Transistors" (SETs) with characteristics resembling those of the usual FETs, but at a new quantitative level. Analysis shows that the physics of the SETs allows much smaller dimensions, higher cutoff frequencies and much lower power consumption than for their semiconductor counterparts. New transistors can be apparently used to achieve extremely large integration scales, possibly opening a way to three-dimensional and molecular-level integration.