Electronic Properties of Graphene Nanoribbon on Si(001) Substrate

TL;DR

This study uses first-principles calculations to explore how the electronic properties of zigzag graphene nanoribbons on Si(001) vary with width and orientation, revealing conditions for energy gap opening and metallic behavior.

Contribution

It provides new insights into the width and orientation dependence of electronic properties of Z-GNRs on Si(001), highlighting the role of interface hybridization and adsorption configuration.

Findings

Narrow Z-GNRs with even rows have an energy gap when adsorbed perpendicularly.

Wider Z-GNRs exhibit metallic behavior due to width-dependent hybridization.

Parallel adsorption leads to metallic states regardless of ribbon width.

Abstract

We show by first-principles calculations that the electronic properties of zigzag graphene nanoribbons (Z-GNRs) adsorbed on Si(001) substrate strongly depend on ribbon width and adsorption orientation. Only narrow Z-GNRs with even rows of zigzag chains across their width adsorbed perpendicularly to the Si dimer rows possess an energy gap, while wider Z-GNRs are metallic due to width-dependent interface hybridization. The Z-GNRs can be metastably adsorbed parallel to the Si dimer rows, but show uniform metallic nature independent of ribbon width due to adsorption induced dangling-bond states on the Si surface.