Band-gap engineering and ballistic transport in corrugated graphene nanoribbons

TL;DR

This study investigates how periodic corrugations in graphene nanoribbons influence their electronic band structure and conductance, revealing potential for band-gap engineering and the importance of edge quality.

Contribution

It provides a detailed analysis of band structure modifications and conductance behavior in corrugated graphene nanoribbons with various edge types and corrugation geometries.

Findings

Armchair ribbons can develop band gaps or minibands depending on corrugation type.

Zigzag ribbons are less affected, with minimal band structure changes.

Edge disorder significantly reduces conductance, emphasizing the need for clean samples.

Abstract

We calculate the band structure and the conductance of periodic corrugated graphene nanoribbons within the framework of the tight-binding $p$-orbital model. We consider corrugated structures based on host ribbons with armchair and zigzag edges and three different types of corrugations (armchair edges, zigzag edges as well as a rectangular corrugation). We demonstrate that for armchair host ribbons, depending on the type of corrugation, a band gap or low-velocity minibands appear near the charge neutrality point. For higher energies the allowed Bloch state bands become separated by mini-stopbands. By contrast, for corrugated ribbons with the zigzag host, the corrugations introduce neither band gaps nor stopbands (except for the case of the rectangular corrugations). The conductances of finite corrugated ribbons are analyzed on the basis of the corresponding band structures. For a sufficiently large number of corrugations the conductance follows the number of the corresponding propagating Bloch states and shows pronounced oscillations due to the Fabry-Perot interference within the corrugated segments. Finally we demonstrate that edge disorder strongly affects the conductances of corrugated ribbons. Our results indicate that observation of miniband formation in corrugated ribbons would require clean, edge-disorder free samples, especially for the case of the armchair host lattice.