Peculiar Band Gap Structure of Graphene Nanoribbons

TL;DR

This paper systematically analyzes the electronic band gap structures of graphene nanoribbons, revealing valley patterns, metallic sequences, and oscillations related to edge shape and width, with implications for nanoelectronics.

Contribution

It provides a comprehensive analysis of how edge shape and width influence the band gap structure of graphene nanoribbons, highlighting valley patterns and metallic sequences.

Findings

Zigzag nanoribbons are all metallic.

Armchair nanoribbons are metallic with a period of 3.

Band gaps oscillate with nanoribbon width.

Abstract

Graphene nanoribbons are quasi-one-dimensional meterials with finite width. Characterizing a wide class of nanoribbons by edge shape and width, we make a systematic analysis of their electronic properties. The band gap structure of nanoribbons is shown to exhibit a valley structure with stream-like sequences of metallic or almost metallic nanoribbons. Among them, all zigzag nanoribbons are metallic, and armchair nanoribbons are metallic by period of 3. We find that these stream-like sequences correspond to equi-width curves, and that the band gap of chiral and armchair nanoribbons oscillate as a function of the width. Furthermore a possible application of nanoribbons to nanoelectronics is discussed.