Cryogenic preamplification of a single-electron-transistor using a silicon-germanium heterojunction-bipolar-transistor

TL;DR

This paper demonstrates cryogenic pre-amplification of a single-electron transistor using a silicon-germanium heterojunction bipolar transistor, significantly improving signal-to-noise ratio and transition frequency at low power dissipation.

Contribution

It introduces a novel cryogenic HBT-based pre-amplifier for SETs, enhancing signal detection and frequency response at cryogenic temperatures.

Findings

Signal-to-noise ratio improved by 10-100 times

Transition frequency extended by up to 10 times

Power dissipation remains below 5 μW

Abstract

We examine a silicon-germanium heterojunction bipolar transistor (HBT) for cryogenic pre-amplification of a single electron transistor (SET). The SET current modulates the base current of the HBT directly. The HBT-SET circuit is immersed in liquid helium, and its frequency response from low frequency to several MHz is measured. The current gain and the noise spectrum with the HBT result in a signal-to-noise-ratio (SNR) that is a factor of 10-100 larger than without the HBT at lower frequencies. The transition frequency defined by SNR = 1 has been extended by as much as a factor of 10 compared to without the HBT amplification. The power dissipated by the HBT cryogenic pre-amplifier is approximately 5 nW to 5 {\mu}W for the investigated range of operation. The circuit is also operated in a single electron charge read-out configuration in the time-domain as a proof-of-principle demonstration of the amplification approach for single spin read-out.