Numerical Techniques for the Analysis of Charge Transport and Electrodynamics in Graphene Nanoribbons

Luca Pierantoni,Davide Mencarelli

doi:10.5772/55132

Abstract

In this paper, we report on multiphysics full-wave techniques in the frequency (energy)-domain and the time-domain, aimed at the investigation of the combined electromagnetic-coherent transport problem in carbon based on nano-structured materials and devices, e.g., graphene nanoribbons. The frequency-domain approach is introduced in order to describe a Poisson/Schrödinger system in a quasi static framework. An example of the self-consistent solution of laterally coupled graphene nanoribbons is shown. The time-domain approach deals with the solution of the combined Maxwell/Schrödinger system of equations. The propagation of a charge wavepacket is reported, showing the effect of the self-generated electromagnetic field that affects the dynamics of the charge wavepacket.

Highlights

The theoretical, scientific and technological relevance of carbon‐based materials have been highlighted in a variety of works, both experimental and theoretical [1,2,3,4,5,6,7,8,9,10,11]
In order to show the potentialities of our approaches, in the following we show the comparison between the potential distributions in a region occupied by two laterally coupled graphene nanoribbon (GNR)
It is noted that the self‐consistent potential of fig. 4b is strongly different from the potential of fig 4a; as largely expected, changing the distance between the GNR does not imply a potential “composition” following a superposition of effects ‐ the iterative process develops very differently in the two cases and the final results are not predictable

Summary

Introduction

The theoretical, scientific and technological relevance of carbon‐based materials (carbon nanotubes, graphene) have been highlighted in a variety of works, both experimental and theoretical [1,2,3,4,5,6,7,8,9,10,11]. The analysis of charge transport in carbon nano‐structures can be carried out by discrete models, such as tight binding (TB), and continuous models, such as effective mass and k∙p approximations, which stem from the approximation of TB around particular points of the dispersion curves These techniques are suited for the analysis of CNT/graphene/GNR in a variety of problems such as bending [17,18], lattice defects and discontinuities [14], and edge terminations [19,20]. 1A3n:2al0y1si2s 1 of Charge Transport and Electrodynamics in Graphene Nanoribbons based on carbon materials, namely carbon nanotube (CNT), multiwall (MW) CNT, graphene and graphene nanoribbon (GNR) For both the approaches, the quantum transport is described by the Schrödinger equation or its Dirac‐like counterpart, for small energies. Regarding the time‐domain technique, we show the dynamics of a charge wavepacket from source to drain electrodes in a GNR realistic transistor environment

Frequency‐domain

Time‐domain

Conclusions