Low Bias Negative Differential Resistance in Graphene Nanoribbon Superlattices

TL;DR

This paper theoretically explores negative differential resistance in graphene nanoribbon superlattices at low bias voltages, identifying three transport regimes with potential for device applications.

Contribution

It introduces a combined Dirac Hamiltonian and Landauer-Büttiker approach to analyze NDR in aGNR superlattices across different transport regimes.

Findings

NDR observed at biases as low as 10 mV

Three distinct transport regimes identified

High current density achieved

Abstract

We theoretically investigate negative differential resistance (NDR) for ballistic transport in semiconducting armchair graphene nanoribbon (aGNR) superlattices (5 to 20 barriers) at low bias voltages V_SD < 500 mV. We combine the graphene Dirac Hamiltonian with the Landauer-B\"uttiker formalism to calculate the current I_SD through the system. We find three distinct transport regimes in which NDR occurs: (i) a "classical" regime for wide layers, through which the transport across band gaps is strongly suppressed, leading to alternating regions of nearly unity and zero transmission probabilities as a function of V_SD due to crossing of band gaps from different layers; (ii) a quantum regime dominated by superlattice miniband conduction, with current suppression arising from the misalignment of miniband states with increasing V_SD; and (iii) a Wannier-Stark ladder regime with current peaks occurring at the crossings of Wannier-Stark rungs from distinct ladders. We observe NDR at voltage biases as low as 10 mV with a high current density, making the aGNR superlattices attractive for device applications.