A New Mechanism for THz Detection Based on the Tunneling Effect in Bi-Layer Graphene Nanoribbons

Antonio Maffucci

doi:10.3390/app5041102

Abstract

A new possible mechanism of signal detection in the THz range is investigated, based on the excitation of resonances due to the tunneling effect between two graphene nanoribbons. A simple detector is proposed, where two graphene nanoribbons are used to contact two copper electrodes. The terminal voltages are shown to exhibit strong resonances when the frequency of an external impinging field is tuned to the characteristic tunneling frequency of the graphene layer pair. An electrodynamic model for the electron transport along the graphene nanoribbons is extended here to include the tunneling effect, and a coupled transmission line model is finally derived. This model is able to predict not only the tunneling resonance, but also the well-known plasmon resonances, related to the propagation of slow surface waves.

Highlights

The terahertz range is a fascinating and promising frontier of research for a wide range of technological applications, from medical imaging to security, from astrophysics to consumer electronics [1,2,3]
In the THz range the carbon nanotubes and the graphene nanoribbons allow the propagation of slowly-decaying surface waves, with almost frequency-independent wavenumber and phase velocity usually two order of magnitude smaller than the speed of light in vacuum
In this paper we have investigated a new possible mechanism to detect signals in the THz range, based on the tunneling effect between two adjacent graphene nanoribbons

Summary

Introduction

The terahertz range is a fascinating and promising frontier of research for a wide range of technological applications, from medical imaging to security, from astrophysics to consumer electronics [1,2,3]. Single-mode components (photonic crystals, transmission lines, microcavities, antennas) and lumped elements (capacitors, inductors, resistors, interconnects) have been fabricated by means of nano-sized elements, exploiting their novel electromagnetic properties They are related to their discrete spectrum of energy states, which is a consequence of the spatial confinement of the charge carrier’s motion to sizes comparable with the de Broglie wavelength. In the THz range the carbon nanotubes and the graphene nanoribbons allow the propagation of slowly-decaying surface waves (plasmons), with almost frequency-independent wavenumber and phase velocity usually two order of magnitude smaller than the speed of light in vacuum These properties make graphene-based materials excellent candidates for THz nano-antennas, realized with technologically-affordable lengths, e.g., [17,20,21,22,23]. The model is used to study the new kind of THz resonances arising from the coupling between the two graphene layers, via tunneling

Electrical Response of a Bi-Layer Graphene Nanoribbon THz Detector

A Glimpse at the Graphene Nanoribbon Band Structure

Interpretation of the THz Plasmon Resonances

New THz Resonances for the Tunneling Effect

Conclusions