Single-electron latch with granular film charge leakage suppressor

TL;DR

This paper introduces a single-electron latch utilizing a granular metal film for the middle dot, effectively suppressing charge leakage without parasitic dots, simplifying background charge compensation, and enhancing potential for quantum-dot cellular automata circuits.

Contribution

The novel use of a granular metal film as a charge leakage suppressor in a single-electron latch eliminates parasitic dots and simplifies background charge compensation.

Findings

Granular metal film effectively suppresses charge leakage.

No parasitic dots required, simplifying device design.

Potential applications in single-electron circuits and QCA.

Abstract

A single-electron latch is a device that can be used as a building block for Quantum-dot Cellular Automata (QCA) circuits. It consists of three nanoscale metal "dots" connected in series by tunnel junctions; charging of the dots is controlled by three electrostatic gates. One very important feature of a single-electron latch is its ability to store ("latch") information represented by the location of a single electron within the three dots. To obtain latching, the undesired leakage of charge during the retention time must be suppressed. Previously, to achieve this goal, multiple tunnel junctions were used to connect the three dots. However, this method of charge leakage suppression requires an additional compensation of the background charges affecting each parasitic dot in the array of junctions. We report a single-electron latch where a granular metal film is used to fabricate the middle dot in the latch which concurrently acts as a charge leakage suppressor. This latch has no parasitic dots, therefore the background charge compensation procedure is greatly simplified. We discuss the origins of charge leakage suppression and possible applications of granular metal dots for various single-electron circuits.