Charge sensing in enhancement mode double-top-gated metal-oxide-semiconductor quantum dots

TL;DR

This paper demonstrates lateral charge sensing in a double top-gated MOS quantum dot system, enabling charge detection even when the dot's conduction is suppressed, with results matching a 3D capacitance model.

Contribution

It introduces a method for charge sensing in enhancement mode double-top-gated MOS quantum dots, with experimental validation and capacitance modeling.

Findings

Sharp 2% current changes indicate charge transitions.

Coupling capacitance matches 3D model predictions.

Charge sensing is effective even when conduction is suppressed.

Abstract

Laterally coupled charge sensing of quantum dots is highly desirable, because it enables measurement even when conduction through the quantum dot itself is suppressed. In this work, we demonstrate such charge sensing in a double top gated MOS system. The current through a point contact constriction integrated near a quantum dot shows sharp 2% changes corresponding to charge transitions between the dot and a nearby lead. We extract the coupling capacitance between the charge sensor and the quantum dot, and we show that it agrees well with a 3D capacitance model of the integrated sensor and quantum dot system.