Theoretical study of scattering in graphene ribbons in the presence of structural and atomistic edge roughness

TL;DR

This theoretical study analyzes how structural and atomistic edge roughness affect electron scattering and resistivity in graphene nanoribbons, revealing orientation-dependent transport properties and novel suppression regimes.

Contribution

It introduces an atomistic pseudopotential approach combined with Boltzmann transport equations to model edge roughness effects in graphene ribbons.

Findings

Resistivity varies significantly with ribbon orientation.

Peaks in resistivity correspond to density of states peaks.

Strong suppression of resistivity occurs for zigzag-oriented ribbons.

Abstract

We investigate the diffusive electron-transport properties of charge-doped graphene ribbons and nanoribbons with imperfect edges. We consider different regimes of edge scattering, ranging from wide graphene ribbons with (partially) diffusive edge scattering to ribbons with large width variations and nanoribbons with atomistic edge roughness. For the latter, we introduce an approach based on pseudopotentials, allowing for an atomistic treatment of the band structure and the scattering potential, on the self-consistent solution of the Boltzmann transport equation within the relaxation-time approximation and taking into account the edge-roughness properties and statistics. The resulting resistivity depends strongly on the ribbon orientation, with zigzag (armchair) ribbons showing the smallest (largest) resistivity and intermediate ribbon orientations exhibiting intermediate resistivity values. The results also show clear resistivity peaks, corresponding to peaks in the density of states due to the confinement-induced subband quantization, except for armchair-edge ribbons that show a very strong width dependence because of their claromatic behavior. Furthermore, we identify a strong interplay between the relative position of the two valleys of graphene along the transport direction, the correlation profile of the atomistic edge roughness, and the chiral valley modes, leading to a peculiar strongly suppressed resistivity regime, most pronounced for the zigzag orientation.