Back action of graphene charge detectors on graphene and carbon nanotube quantum dots

TL;DR

This study investigates how graphene charge detectors influence the behavior of graphene and carbon nanotube quantum dots, revealing back action effects that depend on the bias voltage and charge state, explained by simple electron transport models.

Contribution

It introduces a detailed analysis of back action effects of graphene charge detectors on quantum dots, with models explaining the energy transfer mechanisms involved.

Findings

Bias voltage on charge detectors significantly affects quantum dot current.

The models successfully explain the back action effects observed.

Energy distribution broadening depends linearly on the bias voltage.

Abstract

We report on devices based on graphene charge detectors (CDs) capacitively coupled to graphene and carbon nanotube quantum dots (QDs). We focus on back action effects of the CD on the probed QD. A strong influence of the bias voltage applied to the CD on the current through the QD is observed. Depending on the charge state of the QD the current through the QD can either strongly increase or completely reverse as a response to the applied voltage on the CD. To describe the observed behavior we employ two simple models based on single electron transport in QDs with asymmetrically broadened energy distributions of the source and the drain leads. The models successfully explain the back action effects. The extracted distribution broadening shows a linear dependency on the bias voltage applied to the CD. We discuss possible mechanisms mediating the energy transfer between the CD and QD and give an explanation for the origin of the observed asymmetry.