Charge transport through a semiconductor quantum dot-ring nanostructure

TL;DR

This paper investigates how the unique geometry of a concentric dot-ring nanostructure affects its charge transport properties, enabling functionalities like single-electron transistors and current rectifiers.

Contribution

It demonstrates that the transport properties of a dot-ring nanostructure can be significantly tuned by its geometry and confinement potential, unlike simpler quantum dots.

Findings

The DRN can function as a single-electron transistor.

The DRN can act as a current rectifier.

Transport characteristics depend on the confinement potential details.

Abstract

Transport properties of a gated nanostructure depend crucially on the coupling of its states to the states of electrodes. In the case of a single quantum dot the coupling, for a given quantum state, is constant or can be slightly modified by additional gating. In this paper we consider a concentric dot-ring nanostructure (DRN) and show that its transport properties can be drastically modified due to the unique geometry. We calculate the dc current through a DRN in the Coulomb blockade regime and show that it can efficiently work as a single electron transistor or a current rectifier. In both cases the transport characteristics strongly depends on the details of the confinement potential. The calculations are carried out for low and high bias regime, the latter being especially interesting in the context of current rectification due to fast relaxation processes.