Fabrication of undoped AlGaAs/GaAs electron quantum dots

TL;DR

This paper reports the fabrication of a stable, undoped AlGaAs/GaAs quantum dot single electron transistor exhibiting clear Coulomb blockade effects, minimal charge noise, and observable excited state transport, advancing quantum device stability.

Contribution

The work introduces a novel undoped heterostructure fabrication method for quantum dots that enhances device stability and reduces charge noise compared to doped counterparts.

Findings

Stable Coulomb blockade oscillations observed

Minimal conductance drift over time

Detection of excited state transport

Abstract

We have fabricated a quantum dot single electron transistor based on an AlGaAs/GaAs heterostructure without any modulation doping. Our device is very stable from an electronic perspective, with clear Coulomb blockade oscillations, and minimal drift in conductance when the device is set to the midpoint of a Coulomb blockade peak and held at constant gate bias. Bias spectroscopy measurements show typical Coulomb 'diamonds' free of any significant charge fluctuation noise. We also observe excited state transport in our device.