Direct observation of time correlated single-electron tunneling

TL;DR

This paper demonstrates direct detection of time correlated single-electron tunneling oscillations in a tunnel junction array using RF-SET, revealing oscillations at very low currents through electron counting.

Contribution

It presents the first direct observation of time correlated single-electron tunneling oscillations in a series array using RF-SET detection methods.

Findings

Observed oscillations in frequency domain.

Measured currents from 50 to 250 fA.

Confirmed time correlated tunneling behavior.

Abstract

We report a direct detection of time correlated single-electron tunneling oscillations in a series array of small tunnel junctions. Here the current, I, is made up of a lattice of charge solitons moving throughout the array by time correlated tunneling with the frequency f=I/e, where e is the electron charge. To detect the single charges, we have integrated the array with a radio-frequency single-electron transistor (RF-SET) and employed two different methods to couple the array to the SET input: by direct injection through a tunnel junction, and by capacitive coupling. In this paper we report the results from the latter type of charge input, where we have observed the oscillations in the frequency domain and measured currents from 50 to 250 fA by means of electron counting.