Bias and temperature dependence of the noise in a single electron transistor

TL;DR

This study investigates how bias voltage, gain, and temperature influence the current noise in a single electron transistor with Al-AlO_x-Nb junctions, revealing gain-dependent noise components and temperature-activated noise sources near the junctions.

Contribution

It provides the first detailed analysis of the bias and temperature dependence of noise in a single electron transistor with Al-AlO_x-Nb junctions, highlighting gain-dependent noise behavior.

Findings

Gain-dependent component dominates at 10 Hz

Bias affects the differential charge noise

Temperature influences noise sources near junctions

Abstract

A single electron transistor based on Al-AlO_x-Nb tunnel junctions was fabricated by shadow evaporation and in situ barrier formation. Its output current noise was measured, using a transimpedance amplifier setup, as a function of bias voltage, gain, and temperature, in the frequency range 1...300 Hz. The spot noise at 10 Hz is dominated by a gain dependent component, indicating that the main noise contribution comes from fluctuations at the input of the transistor. Deviations from ideal input charge noise behaviour are found in the form of a bias dependence of the differential charge equivalent noise, i. e. the derivative of current noise with respect to gain. The temperature dependence of this effect could indicate that heating is activating the noise sources, and that they are located inside or in the near vicinity of the junctions.