Opening and reversible control of a wide energy gap in uniform monolayer graphene

TL;DR

This paper demonstrates a method to open a wide, reversible energy gap in uniform monolayer graphene using self-assembled sodium nanostrips, enabling potential semiconductor applications without introducing atomic defects.

Contribution

The study introduces a novel, defect-free approach to induce a wide, reversible energy gap in graphene via sodium nanostrips, surpassing previous narrow-gap nanostructures.

Findings

Achieved a 0.74 eV energy gap in graphene.

Reversible control of the energy gap through sodium and oxygen adsorption.

Maintained high mobility despite gap opening.

Abstract

For graphene to be used in semiconductor applications, a wide energy gap of at least 0.5 eV at the Dirac energy must be opened without the introduction of atomic defects. However, such a wide energy gap has not been realized in graphene, except in the cases of narrow, chemically terminated graphene nanostructures with inevitable edge defects. Here, we demonstrated that a wide energy gap of 0.74 eV, which is larger than that of germanium, could be opened in uniform monolayer graphene without the introduction of atomic defects into graphene. The wide energy gap was opened through the adsorption of self-assembled twisted sodium nanostrips. Furthermore, the energy gap was reversibly controllable through the alternate adsorption of sodium and oxygen. The opening of such a wide energy gap with minimal degradation of mobility could improve the applicability of graphene in semiconductor devices, which would result in a major advancement in graphene technology.