Transport properties of graphene quantum dots

TL;DR

This paper theoretically investigates the transport properties of graphene quantum dots formed by segmented ribbons, demonstrating controllable conductance resonances and negative differential resistance through geometrical and electrical tuning.

Contribution

It introduces a detailed theoretical model of graphene quantum dot transport properties using Green's function formalism and explores how geometry and gating influence conductance behaviors.

Findings

Resonant conductance behavior can be tuned by geometrical parameters.

Negative differential resistance observed at low voltages.

Transport properties are modulated by gate voltages.

Abstract

In this work we present a theoretical study of transport properties of a double crossbar junction composed by segments of graphene ribbons with different widths forming a graphene quantum dot structure. The systems are described by a single-band tight binding Hamiltonian and the Green's function formalism using real space renormalization techniques. We show calculations of the local density of states, linear conductance and I-V characteristics. Our results depict a resonant behavior of the conductance in the quantum dot structures which can be controlled by changing geometrical parameters such as the nanoribbon segments widths and relative distance between them. By applying a gate voltage on determined regions of the structure, it is possible to modulate the transport response of the systems. We show that negative differential resistance can be obtained for low values of gate and bias voltages applied.