Self-aligned charge read-out for InAs nanowire quantum dots

TL;DR

This paper presents a self-aligned fabrication method for a highly sensitive charge detector in InAs nanowire quantum dots, enabling precise charge state measurements with high sensitivity and integration efficiency.

Contribution

It introduces a novel single-step fabrication process for integrating a quantum point contact with InAs nanowire quantum dots, enhancing charge detection capabilities.

Findings

Charge detection sensitivity of about 20% per electron added.

Successful measurement of Coulomb diamonds and charging events.

Perfect merging of charge stability diagrams from transport and detection.

Abstract

A highly sensitive charge detector is realized for a quantum dot in an InAs nanowire. We have developed a self-aligned etching process to fabricate in a single step a quantum point contact in a two-dimensional electron gas and a quantum dot in an InAs nanowire. The quantum dot is strongly coupled to the underlying point contact which is used as a charge detector. The addition of one electron to the quantum dot leads to a change of the conductance of the charge detector by typically 20%. The charge sensitivity of the detector is used to measure Coulomb diamonds as well as charging events outside the dot. Charge stability diagrams measured by transport through the quantum dot and charge detection merge perfectly.